1.\" $FreeBSD$ 2.\" $OpenBSD: pf.conf.5,v 1.406 2009/01/31 19:37:12 sobrado Exp $ 3.\" 4.\" Copyright (c) 2002, Daniel Hartmeier 5.\" All rights reserved. 6.\" 7.\" Redistribution and use in source and binary forms, with or without 8.\" modification, are permitted provided that the following conditions 9.\" are met: 10.\" 11.\" - Redistributions of source code must retain the above copyright 12.\" notice, this list of conditions and the following disclaimer. 13.\" - Redistributions in binary form must reproduce the above 14.\" copyright notice, this list of conditions and the following 15.\" disclaimer in the documentation and/or other materials provided 16.\" with the distribution. 17.\" 18.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 19.\" "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 20.\" LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 21.\" FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 22.\" COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 23.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 24.\" BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 25.\" LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER 26.\" CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN 28.\" ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 29.\" POSSIBILITY OF SUCH DAMAGE. 30.\" 31.Dd June 29 2012 32.Dt PF.CONF 5 33.Os 34.Sh NAME 35.Nm pf.conf 36.Nd packet filter configuration file 37.Sh DESCRIPTION 38The 39.Xr pf 4 40packet filter modifies, drops or passes packets according to rules or 41definitions specified in 42.Nm pf.conf . 43.Sh STATEMENT ORDER 44There are seven types of statements in 45.Nm pf.conf : 46.Bl -tag -width xxxx 47.It Cm Macros 48User-defined variables may be defined and used later, simplifying 49the configuration file. 50Macros must be defined before they are referenced in 51.Nm pf.conf . 52.It Cm Tables 53Tables provide a mechanism for increasing the performance and flexibility of 54rules with large numbers of source or destination addresses. 55.It Cm Options 56Options tune the behaviour of the packet filtering engine. 57.It Cm Traffic Normalization Li (e.g. Em scrub ) 58Traffic normalization protects internal machines against inconsistencies 59in Internet protocols and implementations. 60.It Cm Queueing 61Queueing provides rule-based bandwidth control. 62.It Cm Translation Li (Various forms of NAT) 63Translation rules specify how addresses are to be mapped or redirected to 64other addresses. 65.It Cm Packet Filtering 66Packet filtering provides rule-based blocking or passing of packets. 67.El 68.Pp 69With the exception of 70.Cm macros 71and 72.Cm tables , 73the types of statements should be grouped and appear in 74.Nm pf.conf 75in the order shown above, as this matches the operation of the underlying 76packet filtering engine. 77By default 78.Xr pfctl 8 79enforces this order (see 80.Ar set require-order 81below). 82.Pp 83Comments can be put anywhere in the file using a hash mark 84.Pq Sq # , 85and extend to the end of the current line. 86.Pp 87Additional configuration files can be included with the 88.Ic include 89keyword, for example: 90.Bd -literal -offset indent 91include "/etc/pf/sub.filter.conf" 92.Ed 93.Sh MACROS 94Macros can be defined that will later be expanded in context. 95Macro names must start with a letter, and may contain letters, digits 96and underscores. 97Macro names may not be reserved words (for example 98.Ar pass , 99.Ar in , 100.Ar out ) . 101Macros are not expanded inside quotes. 102.Pp 103For example, 104.Bd -literal -offset indent 105ext_if = \&"kue0\&" 106all_ifs = \&"{\&" $ext_if lo0 \&"}\&" 107pass out on $ext_if from any to any 108pass in on $ext_if proto tcp from any to any port 25 109.Ed 110.Sh TABLES 111Tables are named structures which can hold a collection of addresses and 112networks. 113Lookups against tables in 114.Xr pf 4 115are relatively fast, making a single rule with tables much more efficient, 116in terms of 117processor usage and memory consumption, than a large number of rules which 118differ only in IP address (either created explicitly or automatically by rule 119expansion). 120.Pp 121Tables can be used as the source or destination of filter rules, 122.Ar scrub 123rules 124or 125translation rules such as 126.Ar nat 127or 128.Ar rdr 129(see below for details on the various rule types). 130Tables can also be used for the redirect address of 131.Ar nat 132and 133.Ar rdr 134rules and in the routing options of filter rules, but only for 135.Ar round-robin 136pools. 137.Pp 138Tables can be defined with any of the following 139.Xr pfctl 8 140mechanisms. 141As with macros, reserved words may not be used as table names. 142.Bl -tag -width "manually" 143.It Ar manually 144Persistent tables can be manually created with the 145.Ar add 146or 147.Ar replace 148option of 149.Xr pfctl 8 , 150before or after the ruleset has been loaded. 151.It Pa pf.conf 152Table definitions can be placed directly in this file, and loaded at the 153same time as other rules are loaded, atomically. 154Table definitions inside 155.Nm pf.conf 156use the 157.Ar table 158statement, and are especially useful to define non-persistent tables. 159The contents of a pre-existing table defined without a list of addresses 160to initialize it is not altered when 161.Nm pf.conf 162is loaded. 163A table initialized with the empty list, 164.Li { } , 165will be cleared on load. 166.El 167.Pp 168Tables may be defined with the following attributes: 169.Bl -tag -width persist 170.It Ar persist 171The 172.Ar persist 173flag forces the kernel to keep the table even when no rules refer to it. 174If the flag is not set, the kernel will automatically remove the table 175when the last rule referring to it is flushed. 176.It Ar const 177The 178.Ar const 179flag prevents the user from altering the contents of the table once it 180has been created. 181Without that flag, 182.Xr pfctl 8 183can be used to add or remove addresses from the table at any time, even 184when running with 185.Xr securelevel 7 186= 2. 187.It Ar counters 188The 189.Ar counters 190flag enables per-address packet and byte counters which can be displayed with 191.Xr pfctl 8 . 192.El 193.Pp 194For example, 195.Bd -literal -offset indent 196table \*(Ltprivate\*(Gt const { 10/8, 172.16/12, 192.168/16 } 197table \*(Ltbadhosts\*(Gt persist 198block on fxp0 from { \*(Ltprivate\*(Gt, \*(Ltbadhosts\*(Gt } to any 199.Ed 200.Pp 201creates a table called private, to hold RFC 1918 private network 202blocks, and a table called badhosts, which is initially empty. 203A filter rule is set up to block all traffic coming from addresses listed in 204either table. 205The private table cannot have its contents changed and the badhosts table 206will exist even when no active filter rules reference it. 207Addresses may later be added to the badhosts table, so that traffic from 208these hosts can be blocked by using 209.Bd -literal -offset indent 210# pfctl -t badhosts -Tadd 204.92.77.111 211.Ed 212.Pp 213A table can also be initialized with an address list specified in one or more 214external files, using the following syntax: 215.Bd -literal -offset indent 216table \*(Ltspam\*(Gt persist file \&"/etc/spammers\&" file \&"/etc/openrelays\&" 217block on fxp0 from \*(Ltspam\*(Gt to any 218.Ed 219.Pp 220The files 221.Pa /etc/spammers 222and 223.Pa /etc/openrelays 224list IP addresses, one per line. 225Any lines beginning with a # are treated as comments and ignored. 226In addition to being specified by IP address, hosts may also be 227specified by their hostname. 228When the resolver is called to add a hostname to a table, 229.Em all 230resulting IPv4 and IPv6 addresses are placed into the table. 231IP addresses can also be entered in a table by specifying a valid interface 232name, a valid interface group or the 233.Em self 234keyword, in which case all addresses assigned to the interface(s) will be 235added to the table. 236.Sh OPTIONS 237.Xr pf 4 238may be tuned for various situations using the 239.Ar set 240command. 241.Bl -tag -width xxxx 242.It Ar set timeout 243.Pp 244.Bl -tag -width "src.track" -compact 245.It Ar interval 246Interval between purging expired states and fragments. 247.It Ar frag 248Seconds before an unassembled fragment is expired. 249.It Ar src.track 250Length of time to retain a source tracking entry after the last state 251expires. 252.El 253.Pp 254When a packet matches a stateful connection, the seconds to live for the 255connection will be updated to that of the 256.Ar proto.modifier 257which corresponds to the connection state. 258Each packet which matches this state will reset the TTL. 259Tuning these values may improve the performance of the 260firewall at the risk of dropping valid idle connections. 261.Pp 262.Bl -tag -width xxxx -compact 263.It Ar tcp.first 264The state after the first packet. 265.It Ar tcp.opening 266The state before the destination host ever sends a packet. 267.It Ar tcp.established 268The fully established state. 269.It Ar tcp.closing 270The state after the first FIN has been sent. 271.It Ar tcp.finwait 272The state after both FINs have been exchanged and the connection is closed. 273Some hosts (notably web servers on Solaris) send TCP packets even after closing 274the connection. 275Increasing 276.Ar tcp.finwait 277(and possibly 278.Ar tcp.closing ) 279can prevent blocking of such packets. 280.It Ar tcp.closed 281The state after one endpoint sends an RST. 282.El 283.Pp 284ICMP and UDP are handled in a fashion similar to TCP, but with a much more 285limited set of states: 286.Pp 287.Bl -tag -width xxxx -compact 288.It Ar udp.first 289The state after the first packet. 290.It Ar udp.single 291The state if the source host sends more than one packet but the destination 292host has never sent one back. 293.It Ar udp.multiple 294The state if both hosts have sent packets. 295.It Ar icmp.first 296The state after the first packet. 297.It Ar icmp.error 298The state after an ICMP error came back in response to an ICMP packet. 299.El 300.Pp 301Other protocols are handled similarly to UDP: 302.Pp 303.Bl -tag -width xxxx -compact 304.It Ar other.first 305.It Ar other.single 306.It Ar other.multiple 307.El 308.Pp 309Timeout values can be reduced adaptively as the number of state table 310entries grows. 311.Pp 312.Bl -tag -width xxxx -compact 313.It Ar adaptive.start 314When the number of state entries exceeds this value, adaptive scaling 315begins. 316All timeout values are scaled linearly with factor 317(adaptive.end - number of states) / (adaptive.end - adaptive.start). 318.It Ar adaptive.end 319When reaching this number of state entries, all timeout values become 320zero, effectively purging all state entries immediately. 321This value is used to define the scale factor, it should not actually 322be reached (set a lower state limit, see below). 323.El 324.Pp 325Adaptive timeouts are enabled by default, with an adaptive.start value 326equal to 60% of the state limit, and an adaptive.end value equal to 327120% of the state limit. 328They can be disabled by setting both adaptive.start and adaptive.end to 0. 329.Pp 330The adaptive timeout values can be defined both globally and for each rule. 331When used on a per-rule basis, the values relate to the number of 332states created by the rule, otherwise to the total number of 333states. 334.Pp 335For example: 336.Bd -literal -offset indent 337set timeout tcp.first 120 338set timeout tcp.established 86400 339set timeout { adaptive.start 6000, adaptive.end 12000 } 340set limit states 10000 341.Ed 342.Pp 343With 9000 state table entries, the timeout values are scaled to 50% 344(tcp.first 60, tcp.established 43200). 345.Pp 346.It Ar set loginterface 347Enable collection of packet and byte count statistics for the given 348interface or interface group. 349These statistics can be viewed using 350.Bd -literal -offset indent 351# pfctl -s info 352.Ed 353.Pp 354In this example 355.Xr pf 4 356collects statistics on the interface named dc0: 357.Bd -literal -offset indent 358set loginterface dc0 359.Ed 360.Pp 361One can disable the loginterface using: 362.Bd -literal -offset indent 363set loginterface none 364.Ed 365.Pp 366.It Ar set limit 367Sets hard limits on the memory pools used by the packet filter. 368See 369.Xr zone 9 370for an explanation of memory pools. 371.Pp 372For example, 373.Bd -literal -offset indent 374set limit states 20000 375.Ed 376.Pp 377sets the maximum number of entries in the memory pool used by state table 378entries (generated by 379.Ar pass 380rules which do not specify 381.Ar no state ) 382to 20000. 383Using 384.Bd -literal -offset indent 385set limit frags 20000 386.Ed 387.Pp 388sets the maximum number of entries in the memory pool used for fragment 389reassembly (generated by 390.Ar scrub 391rules) to 20000. 392Using 393.Bd -literal -offset indent 394set limit src-nodes 2000 395.Ed 396.Pp 397sets the maximum number of entries in the memory pool used for tracking 398source IP addresses (generated by the 399.Ar sticky-address 400and 401.Ar src.track 402options) to 2000. 403Using 404.Bd -literal -offset indent 405set limit tables 1000 406set limit table-entries 100000 407.Ed 408.Pp 409sets limits on the memory pools used by tables. 410The first limits the number of tables that can exist to 1000. 411The second limits the overall number of addresses that can be stored 412in tables to 100000. 413.Pp 414Various limits can be combined on a single line: 415.Bd -literal -offset indent 416set limit { states 20000, frags 20000, src-nodes 2000 } 417.Ed 418.Pp 419.It Ar set ruleset-optimization 420.Bl -tag -width xxxxxxxx -compact 421.It Ar none 422Disable the ruleset optimizer. 423.It Ar basic 424Enable basic ruleset optimization. 425This is the default behaviour. 426Basic ruleset optimization does four things to improve the 427performance of ruleset evaluations: 428.Pp 429.Bl -enum -compact 430.It 431remove duplicate rules 432.It 433remove rules that are a subset of another rule 434.It 435combine multiple rules into a table when advantageous 436.It 437re-order the rules to improve evaluation performance 438.El 439.Pp 440.It Ar profile 441Uses the currently loaded ruleset as a feedback profile to tailor the 442ordering of quick rules to actual network traffic. 443.El 444.Pp 445It is important to note that the ruleset optimizer will modify the ruleset 446to improve performance. 447A side effect of the ruleset modification is that per-rule accounting 448statistics will have different meanings than before. 449If per-rule accounting is important for billing purposes or whatnot, 450either the ruleset optimizer should not be used or a label field should 451be added to all of the accounting rules to act as optimization barriers. 452.Pp 453Optimization can also be set as a command-line argument to 454.Xr pfctl 8 , 455overriding the settings in 456.Nm . 457.It Ar set optimization 458Optimize state timeouts for one of the following network environments: 459.Pp 460.Bl -tag -width xxxx -compact 461.It Ar normal 462A normal network environment. 463Suitable for almost all networks. 464.It Ar high-latency 465A high-latency environment (such as a satellite connection). 466.It Ar satellite 467Alias for 468.Ar high-latency . 469.It Ar aggressive 470Aggressively expire connections. 471This can greatly reduce the memory usage of the firewall at the cost of 472dropping idle connections early. 473.It Ar conservative 474Extremely conservative settings. 475Avoid dropping legitimate connections at the 476expense of greater memory utilization (possibly much greater on a busy 477network) and slightly increased processor utilization. 478.El 479.Pp 480For example: 481.Bd -literal -offset indent 482set optimization aggressive 483.Ed 484.Pp 485.It Ar set block-policy 486The 487.Ar block-policy 488option sets the default behaviour for the packet 489.Ar block 490action: 491.Pp 492.Bl -tag -width xxxxxxxx -compact 493.It Ar drop 494Packet is silently dropped. 495.It Ar return 496A TCP RST is returned for blocked TCP packets, 497an ICMP UNREACHABLE is returned for blocked UDP packets, 498and all other packets are silently dropped. 499.El 500.Pp 501For example: 502.Bd -literal -offset indent 503set block-policy return 504.Ed 505.It Ar set state-policy 506The 507.Ar state-policy 508option sets the default behaviour for states: 509.Pp 510.Bl -tag -width group-bound -compact 511.It Ar if-bound 512States are bound to interface. 513.It Ar floating 514States can match packets on any interfaces (the default). 515.El 516.Pp 517For example: 518.Bd -literal -offset indent 519set state-policy if-bound 520.Ed 521.It Ar set state-defaults 522The 523.Ar state-defaults 524option sets the state options for states created from rules 525without an explicit 526.Ar keep state . 527For example: 528.Bd -literal -offset indent 529set state-defaults pflow, no-sync 530.Ed 531.It Ar set hostid 532The 32-bit 533.Ar hostid 534identifies this firewall's state table entries to other firewalls 535in a 536.Xr pfsync 4 537failover cluster. 538By default the hostid is set to a pseudo-random value, however it may be 539desirable to manually configure it, for example to more easily identify the 540source of state table entries. 541.Bd -literal -offset indent 542set hostid 1 543.Ed 544.Pp 545The hostid may be specified in either decimal or hexadecimal. 546.It Ar set require-order 547By default 548.Xr pfctl 8 549enforces an ordering of the statement types in the ruleset to: 550.Em options , 551.Em normalization , 552.Em queueing , 553.Em translation , 554.Em filtering . 555Setting this option to 556.Ar no 557disables this enforcement. 558There may be non-trivial and non-obvious implications to an out of 559order ruleset. 560Consider carefully before disabling the order enforcement. 561.It Ar set fingerprints 562Load fingerprints of known operating systems from the given filename. 563By default fingerprints of known operating systems are automatically 564loaded from 565.Xr pf.os 5 566in 567.Pa /etc 568but can be overridden via this option. 569Setting this option may leave a small period of time where the fingerprints 570referenced by the currently active ruleset are inconsistent until the new 571ruleset finishes loading. 572.Pp 573For example: 574.Pp 575.Dl set fingerprints \&"/etc/pf.os.devel\&" 576.Pp 577.It Ar set skip on Aq Ar ifspec 578List interfaces for which packets should not be filtered. 579Packets passing in or out on such interfaces are passed as if pf was 580disabled, i.e. pf does not process them in any way. 581This can be useful on loopback and other virtual interfaces, when 582packet filtering is not desired and can have unexpected effects. 583For example: 584.Pp 585.Dl set skip on lo0 586.Pp 587.It Ar set debug 588Set the debug 589.Ar level 590to one of the following: 591.Pp 592.Bl -tag -width xxxxxxxxxxxx -compact 593.It Ar none 594Don't generate debug messages. 595.It Ar urgent 596Generate debug messages only for serious errors. 597.It Ar misc 598Generate debug messages for various errors. 599.It Ar loud 600Generate debug messages for common conditions. 601.El 602.El 603.Sh TRAFFIC NORMALIZATION 604Traffic normalization is used to sanitize packet content in such 605a way that there are no ambiguities in packet interpretation on 606the receiving side. 607The normalizer does IP fragment reassembly to prevent attacks 608that confuse intrusion detection systems by sending overlapping 609IP fragments. 610Packet normalization is invoked with the 611.Ar scrub 612directive. 613.Pp 614.Ar scrub 615has the following options: 616.Bl -tag -width xxxx 617.It Ar no-df 618Clears the 619.Ar dont-fragment 620bit from a matching IP packet. 621Some operating systems are known to generate fragmented packets with the 622.Ar dont-fragment 623bit set. 624This is particularly true with NFS. 625.Ar Scrub 626will drop such fragmented 627.Ar dont-fragment 628packets unless 629.Ar no-df 630is specified. 631.Pp 632Unfortunately some operating systems also generate their 633.Ar dont-fragment 634packets with a zero IP identification field. 635Clearing the 636.Ar dont-fragment 637bit on packets with a zero IP ID may cause deleterious results if an 638upstream router later fragments the packet. 639Using the 640.Ar random-id 641modifier (see below) is recommended in combination with the 642.Ar no-df 643modifier to ensure unique IP identifiers. 644.It Ar min-ttl Aq Ar number 645Enforces a minimum TTL for matching IP packets. 646.It Ar max-mss Aq Ar number 647Enforces a maximum MSS for matching TCP packets. 648.It Xo Ar set-tos Aq Ar string 649.No \*(Ba Aq Ar number 650.Xc 651Enforces a 652.Em TOS 653for matching IP packets. 654.Em TOS 655may be 656given as one of 657.Ar lowdelay , 658.Ar throughput , 659.Ar reliability , 660or as either hex or decimal. 661.It Ar random-id 662Replaces the IP identification field with random values to compensate 663for predictable values generated by many hosts. 664This option only applies to packets that are not fragmented 665after the optional fragment reassembly. 666.It Ar fragment reassemble 667Using 668.Ar scrub 669rules, fragments can be reassembled by normalization. 670In this case, fragments are buffered until they form a complete 671packet, and only the completed packet is passed on to the filter. 672The advantage is that filter rules have to deal only with complete 673packets, and can ignore fragments. 674The drawback of caching fragments is the additional memory cost. 675But the full reassembly method is the only method that currently works 676with NAT. 677This is the default behavior of a 678.Ar scrub 679rule if no fragmentation modifier is supplied. 680.It Ar fragment crop 681The default fragment reassembly method is expensive, hence the option 682to crop is provided. 683In this case, 684.Xr pf 4 685will track the fragments and cache a small range descriptor. 686Duplicate fragments are dropped and overlaps are cropped. 687Thus data will only occur once on the wire with ambiguities resolving to 688the first occurrence. 689Unlike the 690.Ar fragment reassemble 691modifier, fragments are not buffered, they are passed as soon as they 692are received. 693The 694.Ar fragment crop 695reassembly mechanism does not yet work with NAT. 696.Pp 697.It Ar fragment drop-ovl 698This option is similar to the 699.Ar fragment crop 700modifier except that all overlapping or duplicate fragments will be 701dropped, and all further corresponding fragments will be 702dropped as well. 703.It Ar reassemble tcp 704Statefully normalizes TCP connections. 705.Ar scrub reassemble tcp 706rules may not have the direction (in/out) specified. 707.Ar reassemble tcp 708performs the following normalizations: 709.Pp 710.Bl -tag -width timeout -compact 711.It ttl 712Neither side of the connection is allowed to reduce their IP TTL. 713An attacker may send a packet such that it reaches the firewall, affects 714the firewall state, and expires before reaching the destination host. 715.Ar reassemble tcp 716will raise the TTL of all packets back up to the highest value seen on 717the connection. 718.It timestamp modulation 719Modern TCP stacks will send a timestamp on every TCP packet and echo 720the other endpoint's timestamp back to them. 721Many operating systems will merely start the timestamp at zero when 722first booted, and increment it several times a second. 723The uptime of the host can be deduced by reading the timestamp and multiplying 724by a constant. 725Also observing several different timestamps can be used to count hosts 726behind a NAT device. 727And spoofing TCP packets into a connection requires knowing or guessing 728valid timestamps. 729Timestamps merely need to be monotonically increasing and not derived off a 730guessable base time. 731.Ar reassemble tcp 732will cause 733.Ar scrub 734to modulate the TCP timestamps with a random number. 735.It extended PAWS checks 736There is a problem with TCP on long fat pipes, in that a packet might get 737delayed for longer than it takes the connection to wrap its 32-bit sequence 738space. 739In such an occurrence, the old packet would be indistinguishable from a 740new packet and would be accepted as such. 741The solution to this is called PAWS: Protection Against Wrapped Sequence 742numbers. 743It protects against it by making sure the timestamp on each packet does 744not go backwards. 745.Ar reassemble tcp 746also makes sure the timestamp on the packet does not go forward more 747than the RFC allows. 748By doing this, 749.Xr pf 4 750artificially extends the security of TCP sequence numbers by 10 to 18 751bits when the host uses appropriately randomized timestamps, since a 752blind attacker would have to guess the timestamp as well. 753.El 754.El 755.Pp 756For example, 757.Bd -literal -offset indent 758scrub in on $ext_if all fragment reassemble 759.Ed 760.Pp 761The 762.Ar no 763option prefixed to a scrub rule causes matching packets to remain unscrubbed, 764much in the same way as 765.Ar drop quick 766works in the packet filter (see below). 767This mechanism should be used when it is necessary to exclude specific packets 768from broader scrub rules. 769.Sh QUEUEING 770The ALTQ system is currently not available in the GENERIC kernel nor as 771loadable modules. 772In order to use the herein after called queueing options one has to use a 773custom built kernel. 774Please refer to 775.Xr altq 4 776to learn about the related kernel options. 777.Pp 778Packets can be assigned to queues for the purpose of bandwidth 779control. 780At least two declarations are required to configure queues, and later 781any packet filtering rule can reference the defined queues by name. 782During the filtering component of 783.Nm pf.conf , 784the last referenced 785.Ar queue 786name is where any packets from 787.Ar pass 788rules will be queued, while for 789.Ar block 790rules it specifies where any resulting ICMP or TCP RST 791packets should be queued. 792The 793.Ar scheduler 794defines the algorithm used to decide which packets get delayed, dropped, or 795sent out immediately. 796There are three 797.Ar schedulers 798currently supported. 799.Bl -tag -width xxxx 800.It Ar cbq 801Class Based Queueing. 802.Ar Queues 803attached to an interface build a tree, thus each 804.Ar queue 805can have further child 806.Ar queues . 807Each queue can have a 808.Ar priority 809and a 810.Ar bandwidth 811assigned. 812.Ar Priority 813mainly controls the time packets take to get sent out, while 814.Ar bandwidth 815has primarily effects on throughput. 816.Ar cbq 817achieves both partitioning and sharing of link bandwidth 818by hierarchically structured classes. 819Each class has its own 820.Ar queue 821and is assigned its share of 822.Ar bandwidth . 823A child class can borrow bandwidth from its parent class 824as long as excess bandwidth is available 825(see the option 826.Ar borrow , 827below). 828.It Ar priq 829Priority Queueing. 830.Ar Queues 831are flat attached to the interface, thus, 832.Ar queues 833cannot have further child 834.Ar queues . 835Each 836.Ar queue 837has a unique 838.Ar priority 839assigned, ranging from 0 to 15. 840Packets in the 841.Ar queue 842with the highest 843.Ar priority 844are processed first. 845.It Ar hfsc 846Hierarchical Fair Service Curve. 847.Ar Queues 848attached to an interface build a tree, thus each 849.Ar queue 850can have further child 851.Ar queues . 852Each queue can have a 853.Ar priority 854and a 855.Ar bandwidth 856assigned. 857.Ar Priority 858mainly controls the time packets take to get sent out, while 859.Ar bandwidth 860primarily affects throughput. 861.Ar hfsc 862supports both link-sharing and guaranteed real-time services. 863It employs a service curve based QoS model, 864and its unique feature is an ability to decouple 865.Ar delay 866and 867.Ar bandwidth 868allocation. 869.El 870.Pp 871The interfaces on which queueing should be activated are declared using 872the 873.Ar altq on 874declaration. 875.Ar altq on 876has the following keywords: 877.Bl -tag -width xxxx 878.It Aq Ar interface 879Queueing is enabled on the named interface. 880.It Aq Ar scheduler 881Specifies which queueing scheduler to use. 882Currently supported values 883are 884.Ar cbq 885for Class Based Queueing, 886.Ar priq 887for Priority Queueing and 888.Ar hfsc 889for the Hierarchical Fair Service Curve scheduler. 890.It Ar bandwidth Aq Ar bw 891The maximum bitrate for all queues on an 892interface may be specified using the 893.Ar bandwidth 894keyword. 895The value can be specified as an absolute value or as a 896percentage of the interface bandwidth. 897When using an absolute value, the suffixes 898.Ar b , 899.Ar Kb , 900.Ar Mb , 901and 902.Ar Gb 903are used to represent bits, kilobits, megabits, and 904gigabits per second, respectively. 905The value must not exceed the interface bandwidth. 906If 907.Ar bandwidth 908is not specified, the interface bandwidth is used 909(but take note that some interfaces do not know their bandwidth, 910or can adapt their bandwidth rates). 911.It Ar qlimit Aq Ar limit 912The maximum number of packets held in the queue. 913The default is 50. 914.It Ar tbrsize Aq Ar size 915Adjusts the size, in bytes, of the token bucket regulator. 916If not specified, heuristics based on the 917interface bandwidth are used to determine the size. 918.It Ar queue Aq Ar list 919Defines a list of subqueues to create on an interface. 920.El 921.Pp 922In the following example, the interface dc0 923should queue up to 5Mbps in four second-level queues using 924Class Based Queueing. 925Those four queues will be shown in a later example. 926.Bd -literal -offset indent 927altq on dc0 cbq bandwidth 5Mb queue { std, http, mail, ssh } 928.Ed 929.Pp 930Once interfaces are activated for queueing using the 931.Ar altq 932directive, a sequence of 933.Ar queue 934directives may be defined. 935The name associated with a 936.Ar queue 937must match a queue defined in the 938.Ar altq 939directive (e.g. mail), or, except for the 940.Ar priq 941.Ar scheduler , 942in a parent 943.Ar queue 944declaration. 945The following keywords can be used: 946.Bl -tag -width xxxx 947.It Ar on Aq Ar interface 948Specifies the interface the queue operates on. 949If not given, it operates on all matching interfaces. 950.It Ar bandwidth Aq Ar bw 951Specifies the maximum bitrate to be processed by the queue. 952This value must not exceed the value of the parent 953.Ar queue 954and can be specified as an absolute value or a percentage of the parent 955queue's bandwidth. 956If not specified, defaults to 100% of the parent queue's bandwidth. 957The 958.Ar priq 959scheduler does not support bandwidth specification. 960.It Ar priority Aq Ar level 961Between queues a priority level can be set. 962For 963.Ar cbq 964and 965.Ar hfsc , 966the range is 0 to 7 and for 967.Ar priq , 968the range is 0 to 15. 969The default for all is 1. 970.Ar Priq 971queues with a higher priority are always served first. 972.Ar Cbq 973and 974.Ar Hfsc 975queues with a higher priority are preferred in the case of overload. 976.It Ar qlimit Aq Ar limit 977The maximum number of packets held in the queue. 978The default is 50. 979.El 980.Pp 981The 982.Ar scheduler 983can get additional parameters with 984.Xo Aq Ar scheduler 985.Pf ( Aq Ar parameters ) . 986.Xc 987Parameters are as follows: 988.Bl -tag -width Fl 989.It Ar default 990Packets not matched by another queue are assigned to this one. 991Exactly one default queue is required. 992.It Ar red 993Enable RED (Random Early Detection) on this queue. 994RED drops packets with a probability proportional to the average 995queue length. 996.It Ar rio 997Enables RIO on this queue. 998RIO is RED with IN/OUT, thus running 999RED two times more than RIO would achieve the same effect. 1000RIO is currently not supported in the GENERIC kernel. 1001.It Ar ecn 1002Enables ECN (Explicit Congestion Notification) on this queue. 1003ECN implies RED. 1004.El 1005.Pp 1006The 1007.Ar cbq 1008.Ar scheduler 1009supports an additional option: 1010.Bl -tag -width Fl 1011.It Ar borrow 1012The queue can borrow bandwidth from the parent. 1013.El 1014.Pp 1015The 1016.Ar hfsc 1017.Ar scheduler 1018supports some additional options: 1019.Bl -tag -width Fl 1020.It Ar realtime Aq Ar sc 1021The minimum required bandwidth for the queue. 1022.It Ar upperlimit Aq Ar sc 1023The maximum allowed bandwidth for the queue. 1024.It Ar linkshare Aq Ar sc 1025The bandwidth share of a backlogged queue. 1026.El 1027.Pp 1028.Aq Ar sc 1029is an acronym for 1030.Ar service curve . 1031.Pp 1032The format for service curve specifications is 1033.Ar ( m1 , d , m2 ) . 1034.Ar m2 1035controls the bandwidth assigned to the queue. 1036.Ar m1 1037and 1038.Ar d 1039are optional and can be used to control the initial bandwidth assignment. 1040For the first 1041.Ar d 1042milliseconds the queue gets the bandwidth given as 1043.Ar m1 , 1044afterwards the value given in 1045.Ar m2 . 1046.Pp 1047Furthermore, with 1048.Ar cbq 1049and 1050.Ar hfsc , 1051child queues can be specified as in an 1052.Ar altq 1053declaration, thus building a tree of queues using a part of 1054their parent's bandwidth. 1055.Pp 1056Packets can be assigned to queues based on filter rules by using the 1057.Ar queue 1058keyword. 1059Normally only one 1060.Ar queue 1061is specified; when a second one is specified it will instead be used for 1062packets which have a 1063.Em TOS 1064of 1065.Em lowdelay 1066and for TCP ACKs with no data payload. 1067.Pp 1068To continue the previous example, the examples below would specify the 1069four referenced 1070queues, plus a few child queues. 1071Interactive 1072.Xr ssh 1 1073sessions get priority over bulk transfers like 1074.Xr scp 1 1075and 1076.Xr sftp 1 . 1077The queues may then be referenced by filtering rules (see 1078.Sx PACKET FILTERING 1079below). 1080.Bd -literal 1081queue std bandwidth 10% cbq(default) 1082queue http bandwidth 60% priority 2 cbq(borrow red) \e 1083 { employees, developers } 1084queue developers bandwidth 75% cbq(borrow) 1085queue employees bandwidth 15% 1086queue mail bandwidth 10% priority 0 cbq(borrow ecn) 1087queue ssh bandwidth 20% cbq(borrow) { ssh_interactive, ssh_bulk } 1088queue ssh_interactive bandwidth 50% priority 7 cbq(borrow) 1089queue ssh_bulk bandwidth 50% priority 0 cbq(borrow) 1090 1091block return out on dc0 inet all queue std 1092pass out on dc0 inet proto tcp from $developerhosts to any port 80 \e 1093 queue developers 1094pass out on dc0 inet proto tcp from $employeehosts to any port 80 \e 1095 queue employees 1096pass out on dc0 inet proto tcp from any to any port 22 \e 1097 queue(ssh_bulk, ssh_interactive) 1098pass out on dc0 inet proto tcp from any to any port 25 \e 1099 queue mail 1100.Ed 1101.Sh TRANSLATION 1102Translation rules modify either the source or destination address of the 1103packets associated with a stateful connection. 1104A stateful connection is automatically created to track packets matching 1105such a rule as long as they are not blocked by the filtering section of 1106.Nm pf.conf . 1107The translation engine modifies the specified address and/or port in the 1108packet, recalculates IP, TCP and UDP checksums as necessary, and passes it to 1109the packet filter for evaluation. 1110.Pp 1111Since translation occurs before filtering the filter 1112engine will see packets as they look after any 1113addresses and ports have been translated. 1114Filter rules will therefore have to filter based on the translated 1115address and port number. 1116Packets that match a translation rule are only automatically passed if 1117the 1118.Ar pass 1119modifier is given, otherwise they are 1120still subject to 1121.Ar block 1122and 1123.Ar pass 1124rules. 1125.Pp 1126The state entry created permits 1127.Xr pf 4 1128to keep track of the original address for traffic associated with that state 1129and correctly direct return traffic for that connection. 1130.Pp 1131Various types of translation are possible with pf: 1132.Bl -tag -width xxxx 1133.It Ar binat 1134A 1135.Ar binat 1136rule specifies a bidirectional mapping between an external IP netblock 1137and an internal IP netblock. 1138.It Ar nat 1139A 1140.Ar nat 1141rule specifies that IP addresses are to be changed as the packet 1142traverses the given interface. 1143This technique allows one or more IP addresses 1144on the translating host to support network traffic for a larger range of 1145machines on an "inside" network. 1146Although in theory any IP address can be used on the inside, it is strongly 1147recommended that one of the address ranges defined by RFC 1918 be used. 1148These netblocks are: 1149.Bd -literal 115010.0.0.0 - 10.255.255.255 (all of net 10, i.e., 10/8) 1151172.16.0.0 - 172.31.255.255 (i.e., 172.16/12) 1152192.168.0.0 - 192.168.255.255 (i.e., 192.168/16) 1153.Ed 1154.It Pa rdr 1155The packet is redirected to another destination and possibly a 1156different port. 1157.Ar rdr 1158rules can optionally specify port ranges instead of single ports. 1159rdr ... port 2000:2999 -\*(Gt ... port 4000 1160redirects ports 2000 to 2999 (inclusive) to port 4000. 1161rdr ... port 2000:2999 -\*(Gt ... port 4000:* 1162redirects port 2000 to 4000, 2001 to 4001, ..., 2999 to 4999. 1163.El 1164.Pp 1165In addition to modifying the address, some translation rules may modify 1166source or destination ports for 1167.Xr tcp 4 1168or 1169.Xr udp 4 1170connections; implicitly in the case of 1171.Ar nat 1172rules and explicitly in the case of 1173.Ar rdr 1174rules. 1175Port numbers are never translated with a 1176.Ar binat 1177rule. 1178.Pp 1179Evaluation order of the translation rules is dependent on the type 1180of the translation rules and of the direction of a packet. 1181.Ar binat 1182rules are always evaluated first. 1183Then either the 1184.Ar rdr 1185rules are evaluated on an inbound packet or the 1186.Ar nat 1187rules on an outbound packet. 1188Rules of the same type are evaluated in the same order in which they 1189appear in the ruleset. 1190The first matching rule decides what action is taken. 1191.Pp 1192The 1193.Ar no 1194option prefixed to a translation rule causes packets to remain untranslated, 1195much in the same way as 1196.Ar drop quick 1197works in the packet filter (see below). 1198If no rule matches the packet it is passed to the filter engine unmodified. 1199.Pp 1200Translation rules apply only to packets that pass through 1201the specified interface, and if no interface is specified, 1202translation is applied to packets on all interfaces. 1203For instance, redirecting port 80 on an external interface to an internal 1204web server will only work for connections originating from the outside. 1205Connections to the address of the external interface from local hosts will 1206not be redirected, since such packets do not actually pass through the 1207external interface. 1208Redirections cannot reflect packets back through the interface they arrive 1209on, they can only be redirected to hosts connected to different interfaces 1210or to the firewall itself. 1211.Pp 1212Note that redirecting external incoming connections to the loopback 1213address, as in 1214.Bd -literal -offset indent 1215rdr on ne3 inet proto tcp to port smtp -\*(Gt 127.0.0.1 port spamd 1216.Ed 1217.Pp 1218will effectively allow an external host to connect to daemons 1219bound solely to the loopback address, circumventing the traditional 1220blocking of such connections on a real interface. 1221Unless this effect is desired, any of the local non-loopback addresses 1222should be used as redirection target instead, which allows external 1223connections only to daemons bound to this address or not bound to 1224any address. 1225.Pp 1226See 1227.Sx TRANSLATION EXAMPLES 1228below. 1229.Sh PACKET FILTERING 1230.Xr pf 4 1231has the ability to 1232.Ar block 1233and 1234.Ar pass 1235packets based on attributes of their layer 3 (see 1236.Xr ip 4 1237and 1238.Xr ip6 4 ) 1239and layer 4 (see 1240.Xr icmp 4 , 1241.Xr icmp6 4 , 1242.Xr tcp 4 , 1243.Xr udp 4 ) 1244headers. 1245In addition, packets may also be 1246assigned to queues for the purpose of bandwidth control. 1247.Pp 1248For each packet processed by the packet filter, the filter rules are 1249evaluated in sequential order, from first to last. 1250The last matching rule decides what action is taken. 1251If no rule matches the packet, the default action is to pass 1252the packet. 1253.Pp 1254The following actions can be used in the filter: 1255.Bl -tag -width xxxx 1256.It Ar block 1257The packet is blocked. 1258There are a number of ways in which a 1259.Ar block 1260rule can behave when blocking a packet. 1261The default behaviour is to 1262.Ar drop 1263packets silently, however this can be overridden or made 1264explicit either globally, by setting the 1265.Ar block-policy 1266option, or on a per-rule basis with one of the following options: 1267.Pp 1268.Bl -tag -width xxxx -compact 1269.It Ar drop 1270The packet is silently dropped. 1271.It Ar return-rst 1272This applies only to 1273.Xr tcp 4 1274packets, and issues a TCP RST which closes the 1275connection. 1276.It Ar return-icmp 1277.It Ar return-icmp6 1278This causes ICMP messages to be returned for packets which match the rule. 1279By default this is an ICMP UNREACHABLE message, however this 1280can be overridden by specifying a message as a code or number. 1281.It Ar return 1282This causes a TCP RST to be returned for 1283.Xr tcp 4 1284packets and an ICMP UNREACHABLE for UDP and other packets. 1285.El 1286.Pp 1287Options returning ICMP packets currently have no effect if 1288.Xr pf 4 1289operates on a 1290.Xr if_bridge 4 , 1291as the code to support this feature has not yet been implemented. 1292.Pp 1293The simplest mechanism to block everything by default and only pass 1294packets that match explicit rules is specify a first filter rule of: 1295.Bd -literal -offset indent 1296block all 1297.Ed 1298.It Ar pass 1299The packet is passed; 1300state is created unless the 1301.Ar no state 1302option is specified. 1303.El 1304.Pp 1305By default 1306.Xr pf 4 1307filters packets statefully; the first time a packet matches a 1308.Ar pass 1309rule, a state entry is created; for subsequent packets the filter checks 1310whether the packet matches any state. 1311If it does, the packet is passed without evaluation of any rules. 1312After the connection is closed or times out, the state entry is automatically 1313removed. 1314.Pp 1315This has several advantages. 1316For TCP connections, comparing a packet to a state involves checking 1317its sequence numbers, as well as TCP timestamps if a 1318.Ar scrub reassemble tcp 1319rule applies to the connection. 1320If these values are outside the narrow windows of expected 1321values, the packet is dropped. 1322This prevents spoofing attacks, such as when an attacker sends packets with 1323a fake source address/port but does not know the connection's sequence 1324numbers. 1325Similarly, 1326.Xr pf 4 1327knows how to match ICMP replies to states. 1328For example, 1329.Bd -literal -offset indent 1330pass out inet proto icmp all icmp-type echoreq 1331.Ed 1332.Pp 1333allows echo requests (such as those created by 1334.Xr ping 8 ) 1335out statefully, and matches incoming echo replies correctly to states. 1336.Pp 1337Also, looking up states is usually faster than evaluating rules. 1338If there are 50 rules, all of them are evaluated sequentially in O(n). 1339Even with 50000 states, only 16 comparisons are needed to match a 1340state, since states are stored in a binary search tree that allows 1341searches in O(log2 n). 1342.Pp 1343Furthermore, correct handling of ICMP error messages is critical to 1344many protocols, particularly TCP. 1345.Xr pf 4 1346matches ICMP error messages to the correct connection, checks them against 1347connection parameters, and passes them if appropriate. 1348For example if an ICMP source quench message referring to a stateful TCP 1349connection arrives, it will be matched to the state and get passed. 1350.Pp 1351Finally, state tracking is required for 1352.Ar nat , binat No and Ar rdr 1353rules, in order to track address and port translations and reverse the 1354translation on returning packets. 1355.Pp 1356.Xr pf 4 1357will also create state for other protocols which are effectively stateless by 1358nature. 1359UDP packets are matched to states using only host addresses and ports, 1360and other protocols are matched to states using only the host addresses. 1361.Pp 1362If stateless filtering of individual packets is desired, 1363the 1364.Ar no state 1365keyword can be used to specify that state will not be created 1366if this is the last matching rule. 1367A number of parameters can also be set to affect how 1368.Xr pf 4 1369handles state tracking. 1370See 1371.Sx STATEFUL TRACKING OPTIONS 1372below for further details. 1373.Sh PARAMETERS 1374The rule parameters specify the packets to which a rule applies. 1375A packet always comes in on, or goes out through, one interface. 1376Most parameters are optional. 1377If a parameter is specified, the rule only applies to packets with 1378matching attributes. 1379Certain parameters can be expressed as lists, in which case 1380.Xr pfctl 8 1381generates all needed rule combinations. 1382.Bl -tag -width xxxx 1383.It Ar in No or Ar out 1384This rule applies to incoming or outgoing packets. 1385If neither 1386.Ar in 1387nor 1388.Ar out 1389are specified, the rule will match packets in both directions. 1390.It Ar log 1391In addition to the action specified, a log message is generated. 1392Only the packet that establishes the state is logged, 1393unless the 1394.Ar no state 1395option is specified. 1396The logged packets are sent to a 1397.Xr pflog 4 1398interface, by default 1399.Ar pflog0 . 1400This interface is monitored by the 1401.Xr pflogd 8 1402logging daemon, which dumps the logged packets to the file 1403.Pa /var/log/pflog 1404in 1405.Xr pcap 3 1406binary format. 1407.It Ar log (all) 1408Used to force logging of all packets for a connection. 1409This is not necessary when 1410.Ar no state 1411is explicitly specified. 1412As with 1413.Ar log , 1414packets are logged to 1415.Xr pflog 4 . 1416.It Ar log (user) 1417Logs the 1418.Ux 1419user ID of the user that owns the socket and the PID of the process that 1420has the socket open where the packet is sourced from or destined to 1421(depending on which socket is local). 1422This is in addition to the normal information logged. 1423.Pp 1424Only the first packet 1425logged via 1426.Ar log (all, user) 1427will have the user credentials logged when using stateful matching. 1428.It Ar log (to Aq Ar interface ) 1429Send logs to the specified 1430.Xr pflog 4 1431interface instead of 1432.Ar pflog0 . 1433.It Ar quick 1434If a packet matches a rule which has the 1435.Ar quick 1436option set, this rule 1437is considered the last matching rule, and evaluation of subsequent rules 1438is skipped. 1439.It Ar on Aq Ar interface 1440This rule applies only to packets coming in on, or going out through, this 1441particular interface or interface group. 1442For more information on interface groups, 1443see the 1444.Ic group 1445keyword in 1446.Xr ifconfig 8 . 1447.It Aq Ar af 1448This rule applies only to packets of this address family. 1449Supported values are 1450.Ar inet 1451and 1452.Ar inet6 . 1453.It Ar proto Aq Ar protocol 1454This rule applies only to packets of this protocol. 1455Common protocols are 1456.Xr icmp 4 , 1457.Xr icmp6 4 , 1458.Xr tcp 4 , 1459and 1460.Xr udp 4 . 1461For a list of all the protocol name to number mappings used by 1462.Xr pfctl 8 , 1463see the file 1464.Em /etc/protocols . 1465.It Xo 1466.Ar from Aq Ar source 1467.Ar port Aq Ar source 1468.Ar os Aq Ar source 1469.Ar to Aq Ar dest 1470.Ar port Aq Ar dest 1471.Xc 1472This rule applies only to packets with the specified source and destination 1473addresses and ports. 1474.Pp 1475Addresses can be specified in CIDR notation (matching netblocks), as 1476symbolic host names, interface names or interface group names, or as any 1477of the following keywords: 1478.Pp 1479.Bl -tag -width xxxxxxxxxxxxxx -compact 1480.It Ar any 1481Any address. 1482.It Ar no-route 1483Any address which is not currently routable. 1484.It Ar urpf-failed 1485Any source address that fails a unicast reverse path forwarding (URPF) 1486check, i.e. packets coming in on an interface other than that which holds 1487the route back to the packet's source address. 1488.It Aq Ar table 1489Any address that matches the given table. 1490.El 1491.Pp 1492Ranges of addresses are specified by using the 1493.Sq - 1494operator. 1495For instance: 1496.Dq 10.1.1.10 - 10.1.1.12 1497means all addresses from 10.1.1.10 to 10.1.1.12, 1498hence addresses 10.1.1.10, 10.1.1.11, and 10.1.1.12. 1499.Pp 1500Interface names and interface group names can have modifiers appended: 1501.Pp 1502.Bl -tag -width xxxxxxxxxxxx -compact 1503.It Ar :network 1504Translates to the network(s) attached to the interface. 1505.It Ar :broadcast 1506Translates to the interface's broadcast address(es). 1507.It Ar :peer 1508Translates to the point-to-point interface's peer address(es). 1509.It Ar :0 1510Do not include interface aliases. 1511.El 1512.Pp 1513Host names may also have the 1514.Ar :0 1515option appended to restrict the name resolution to the first of each 1516v4 and v6 address found. 1517.Pp 1518Host name resolution and interface to address translation are done at 1519ruleset load-time. 1520When the address of an interface (or host name) changes (under DHCP or PPP, 1521for instance), the ruleset must be reloaded for the change to be reflected 1522in the kernel. 1523Surrounding the interface name (and optional modifiers) in parentheses 1524changes this behaviour. 1525When the interface name is surrounded by parentheses, the rule is 1526automatically updated whenever the interface changes its address. 1527The ruleset does not need to be reloaded. 1528This is especially useful with 1529.Ar nat . 1530.Pp 1531Ports can be specified either by number or by name. 1532For example, port 80 can be specified as 1533.Em www . 1534For a list of all port name to number mappings used by 1535.Xr pfctl 8 , 1536see the file 1537.Pa /etc/services . 1538.Pp 1539Ports and ranges of ports are specified by using these operators: 1540.Bd -literal -offset indent 1541= (equal) 1542!= (unequal) 1543\*(Lt (less than) 1544\*(Le (less than or equal) 1545\*(Gt (greater than) 1546\*(Ge (greater than or equal) 1547: (range including boundaries) 1548\*(Gt\*(Lt (range excluding boundaries) 1549\*(Lt\*(Gt (except range) 1550.Ed 1551.Pp 1552.Sq \*(Gt\*(Lt , 1553.Sq \*(Lt\*(Gt 1554and 1555.Sq \&: 1556are binary operators (they take two arguments). 1557For instance: 1558.Bl -tag -width Fl 1559.It Ar port 2000:2004 1560means 1561.Sq all ports \*(Ge 2000 and \*(Le 2004 , 1562hence ports 2000, 2001, 2002, 2003 and 2004. 1563.It Ar port 2000 \*(Gt\*(Lt 2004 1564means 1565.Sq all ports \*(Gt 2000 and \*(Lt 2004 , 1566hence ports 2001, 2002 and 2003. 1567.It Ar port 2000 \*(Lt\*(Gt 2004 1568means 1569.Sq all ports \*(Lt 2000 or \*(Gt 2004 , 1570hence ports 1-1999 and 2005-65535. 1571.El 1572.Pp 1573The operating system of the source host can be specified in the case of TCP 1574rules with the 1575.Ar OS 1576modifier. 1577See the 1578.Sx OPERATING SYSTEM FINGERPRINTING 1579section for more information. 1580.Pp 1581The host, port and OS specifications are optional, as in the following examples: 1582.Bd -literal -offset indent 1583pass in all 1584pass in from any to any 1585pass in proto tcp from any port \*(Le 1024 to any 1586pass in proto tcp from any to any port 25 1587pass in proto tcp from 10.0.0.0/8 port \*(Gt 1024 \e 1588 to ! 10.1.2.3 port != ssh 1589pass in proto tcp from any os "OpenBSD" 1590.Ed 1591.It Ar all 1592This is equivalent to "from any to any". 1593.It Ar group Aq Ar group 1594Similar to 1595.Ar user , 1596this rule only applies to packets of sockets owned by the specified group. 1597.It Ar user Aq Ar user 1598This rule only applies to packets of sockets owned by the specified user. 1599For outgoing connections initiated from the firewall, this is the user 1600that opened the connection. 1601For incoming connections to the firewall itself, this is the user that 1602listens on the destination port. 1603For forwarded connections, where the firewall is not a connection endpoint, 1604the user and group are 1605.Em unknown . 1606.Pp 1607All packets, both outgoing and incoming, of one connection are associated 1608with the same user and group. 1609Only TCP and UDP packets can be associated with users; for other protocols 1610these parameters are ignored. 1611.Pp 1612User and group refer to the effective (as opposed to the real) IDs, in 1613case the socket is created by a setuid/setgid process. 1614User and group IDs are stored when a socket is created; 1615when a process creates a listening socket as root (for instance, by 1616binding to a privileged port) and subsequently changes to another 1617user ID (to drop privileges), the credentials will remain root. 1618.Pp 1619User and group IDs can be specified as either numbers or names. 1620The syntax is similar to the one for ports. 1621The value 1622.Em unknown 1623matches packets of forwarded connections. 1624.Em unknown 1625can only be used with the operators 1626.Cm = 1627and 1628.Cm != . 1629Other constructs like 1630.Cm user \*(Ge unknown 1631are invalid. 1632Forwarded packets with unknown user and group ID match only rules 1633that explicitly compare against 1634.Em unknown 1635with the operators 1636.Cm = 1637or 1638.Cm != . 1639For instance 1640.Cm user \*(Ge 0 1641does not match forwarded packets. 1642The following example allows only selected users to open outgoing 1643connections: 1644.Bd -literal -offset indent 1645block out proto { tcp, udp } all 1646pass out proto { tcp, udp } all user { \*(Lt 1000, dhartmei } 1647.Ed 1648.It Xo Ar flags Aq Ar a 1649.Pf / Ns Aq Ar b 1650.No \*(Ba / Ns Aq Ar b 1651.No \*(Ba any 1652.Xc 1653This rule only applies to TCP packets that have the flags 1654.Aq Ar a 1655set out of set 1656.Aq Ar b . 1657Flags not specified in 1658.Aq Ar b 1659are ignored. 1660For stateful connections, the default is 1661.Ar flags S/SA . 1662To indicate that flags should not be checked at all, specify 1663.Ar flags any . 1664The flags are: (F)IN, (S)YN, (R)ST, (P)USH, (A)CK, (U)RG, (E)CE, and C(W)R. 1665.Bl -tag -width Fl 1666.It Ar flags S/S 1667Flag SYN is set. 1668The other flags are ignored. 1669.It Ar flags S/SA 1670This is the default setting for stateful connections. 1671Out of SYN and ACK, exactly SYN may be set. 1672SYN, SYN+PSH and SYN+RST match, but SYN+ACK, ACK and ACK+RST do not. 1673This is more restrictive than the previous example. 1674.It Ar flags /SFRA 1675If the first set is not specified, it defaults to none. 1676All of SYN, FIN, RST and ACK must be unset. 1677.El 1678.Pp 1679Because 1680.Ar flags S/SA 1681is applied by default (unless 1682.Ar no state 1683is specified), only the initial SYN packet of a TCP handshake will create 1684a state for a TCP connection. 1685It is possible to be less restrictive, and allow state creation from 1686intermediate 1687.Pq non-SYN 1688packets, by specifying 1689.Ar flags any . 1690This will cause 1691.Xr pf 4 1692to synchronize to existing connections, for instance 1693if one flushes the state table. 1694However, states created from such intermediate packets may be missing 1695connection details such as the TCP window scaling factor. 1696States which modify the packet flow, such as those affected by 1697.Ar nat , binat No or Ar rdr 1698rules, 1699.Ar modulate No or Ar synproxy state 1700options, or scrubbed with 1701.Ar reassemble tcp 1702will also not be recoverable from intermediate packets. 1703Such connections will stall and time out. 1704.It Xo Ar icmp-type Aq Ar type 1705.Ar code Aq Ar code 1706.Xc 1707.It Xo Ar icmp6-type Aq Ar type 1708.Ar code Aq Ar code 1709.Xc 1710This rule only applies to ICMP or ICMPv6 packets with the specified type 1711and code. 1712Text names for ICMP types and codes are listed in 1713.Xr icmp 4 1714and 1715.Xr icmp6 4 . 1716This parameter is only valid for rules that cover protocols ICMP or 1717ICMP6. 1718The protocol and the ICMP type indicator 1719.Po 1720.Ar icmp-type 1721or 1722.Ar icmp6-type 1723.Pc 1724must match. 1725.It Xo Ar tos Aq Ar string 1726.No \*(Ba Aq Ar number 1727.Xc 1728This rule applies to packets with the specified 1729.Em TOS 1730bits set. 1731.Em TOS 1732may be 1733given as one of 1734.Ar lowdelay , 1735.Ar throughput , 1736.Ar reliability , 1737or as either hex or decimal. 1738.Pp 1739For example, the following rules are identical: 1740.Bd -literal -offset indent 1741pass all tos lowdelay 1742pass all tos 0x10 1743pass all tos 16 1744.Ed 1745.It Ar allow-opts 1746By default, IPv4 packets with IP options or IPv6 packets with routing 1747extension headers are blocked. 1748When 1749.Ar allow-opts 1750is specified for a 1751.Ar pass 1752rule, packets that pass the filter based on that rule (last matching) 1753do so even if they contain IP options or routing extension headers. 1754For packets that match state, the rule that initially created the 1755state is used. 1756The implicit 1757.Ar pass 1758rule that is used when a packet does not match any rules does not 1759allow IP options. 1760.It Ar label Aq Ar string 1761Adds a label (name) to the rule, which can be used to identify the rule. 1762For instance, 1763pfctl -s labels 1764shows per-rule statistics for rules that have labels. 1765.Pp 1766The following macros can be used in labels: 1767.Pp 1768.Bl -tag -width $srcaddr -compact -offset indent 1769.It Ar $if 1770The interface. 1771.It Ar $srcaddr 1772The source IP address. 1773.It Ar $dstaddr 1774The destination IP address. 1775.It Ar $srcport 1776The source port specification. 1777.It Ar $dstport 1778The destination port specification. 1779.It Ar $proto 1780The protocol name. 1781.It Ar $nr 1782The rule number. 1783.El 1784.Pp 1785For example: 1786.Bd -literal -offset indent 1787ips = \&"{ 1.2.3.4, 1.2.3.5 }\&" 1788pass in proto tcp from any to $ips \e 1789 port \*(Gt 1023 label \&"$dstaddr:$dstport\&" 1790.Ed 1791.Pp 1792expands to 1793.Bd -literal -offset indent 1794pass in inet proto tcp from any to 1.2.3.4 \e 1795 port \*(Gt 1023 label \&"1.2.3.4:\*(Gt1023\&" 1796pass in inet proto tcp from any to 1.2.3.5 \e 1797 port \*(Gt 1023 label \&"1.2.3.5:\*(Gt1023\&" 1798.Ed 1799.Pp 1800The macro expansion for the 1801.Ar label 1802directive occurs only at configuration file parse time, not during runtime. 1803.It Xo Ar queue Aq Ar queue 1804.No \*(Ba ( Aq Ar queue , 1805.Aq Ar queue ) 1806.Xc 1807Packets matching this rule will be assigned to the specified queue. 1808If two queues are given, packets which have a 1809.Em TOS 1810of 1811.Em lowdelay 1812and TCP ACKs with no data payload will be assigned to the second one. 1813See 1814.Sx QUEUEING 1815for setup details. 1816.Pp 1817For example: 1818.Bd -literal -offset indent 1819pass in proto tcp to port 25 queue mail 1820pass in proto tcp to port 22 queue(ssh_bulk, ssh_prio) 1821.Ed 1822.It Ar tag Aq Ar string 1823Packets matching this rule will be tagged with the 1824specified string. 1825The tag acts as an internal marker that can be used to 1826identify these packets later on. 1827This can be used, for example, to provide trust between 1828interfaces and to determine if packets have been 1829processed by translation rules. 1830Tags are 1831.Qq sticky , 1832meaning that the packet will be tagged even if the rule 1833is not the last matching rule. 1834Further matching rules can replace the tag with a 1835new one but will not remove a previously applied tag. 1836A packet is only ever assigned one tag at a time. 1837Packet tagging can be done during 1838.Ar nat , 1839.Ar rdr , 1840or 1841.Ar binat 1842rules in addition to filter rules. 1843Tags take the same macros as labels (see above). 1844.It Ar tagged Aq Ar string 1845Used with filter, translation or scrub rules 1846to specify that packets must already 1847be tagged with the given tag in order to match the rule. 1848Inverse tag matching can also be done 1849by specifying the 1850.Cm !\& 1851operator before the 1852.Ar tagged 1853keyword. 1854.It Ar rtable Aq Ar number 1855Used to select an alternate routing table for the routing lookup. 1856Only effective before the route lookup happened, i.e. when filtering inbound. 1857.It Xo Ar divert-to Aq Ar host 1858.Ar port Aq Ar port 1859.Xc 1860Used to redirect packets to a local socket bound to 1861.Ar host 1862and 1863.Ar port . 1864The packets will not be modified, so 1865.Xr getsockname 2 1866on the socket will return the original destination address of the packet. 1867.It Ar divert-reply 1868Used to receive replies for sockets that are bound to addresses 1869which are not local to the machine. 1870See 1871.Xr setsockopt 2 1872for information on how to bind these sockets. 1873.It Ar probability Aq Ar number 1874A probability attribute can be attached to a rule, with a value set between 18750 and 1, bounds not included. 1876In that case, the rule will be honoured using the given probability value 1877only. 1878For example, the following rule will drop 20% of incoming ICMP packets: 1879.Bd -literal -offset indent 1880block in proto icmp probability 20% 1881.Ed 1882.El 1883.Sh ROUTING 1884If a packet matches a rule with a route option set, the packet filter will 1885route the packet according to the type of route option. 1886When such a rule creates state, the route option is also applied to all 1887packets matching the same connection. 1888.Bl -tag -width xxxx 1889.It Ar fastroute 1890The 1891.Ar fastroute 1892option does a normal route lookup to find the next hop for the packet. 1893.It Ar route-to 1894The 1895.Ar route-to 1896option routes the packet to the specified interface with an optional address 1897for the next hop. 1898When a 1899.Ar route-to 1900rule creates state, only packets that pass in the same direction as the 1901filter rule specifies will be routed in this way. 1902Packets passing in the opposite direction (replies) are not affected 1903and are routed normally. 1904.It Ar reply-to 1905The 1906.Ar reply-to 1907option is similar to 1908.Ar route-to , 1909but routes packets that pass in the opposite direction (replies) to the 1910specified interface. 1911Opposite direction is only defined in the context of a state entry, and 1912.Ar reply-to 1913is useful only in rules that create state. 1914It can be used on systems with multiple external connections to 1915route all outgoing packets of a connection through the interface 1916the incoming connection arrived through (symmetric routing enforcement). 1917.It Ar dup-to 1918The 1919.Ar dup-to 1920option creates a duplicate of the packet and routes it like 1921.Ar route-to . 1922The original packet gets routed as it normally would. 1923.El 1924.Sh POOL OPTIONS 1925For 1926.Ar nat 1927and 1928.Ar rdr 1929rules, (as well as for the 1930.Ar route-to , 1931.Ar reply-to 1932and 1933.Ar dup-to 1934rule options) for which there is a single redirection address which has a 1935subnet mask smaller than 32 for IPv4 or 128 for IPv6 (more than one IP 1936address), a variety of different methods for assigning this address can be 1937used: 1938.Bl -tag -width xxxx 1939.It Ar bitmask 1940The 1941.Ar bitmask 1942option applies the network portion of the redirection address to the address 1943to be modified (source with 1944.Ar nat , 1945destination with 1946.Ar rdr ) . 1947.It Ar random 1948The 1949.Ar random 1950option selects an address at random within the defined block of addresses. 1951.It Ar source-hash 1952The 1953.Ar source-hash 1954option uses a hash of the source address to determine the redirection address, 1955ensuring that the redirection address is always the same for a given source. 1956An optional key can be specified after this keyword either in hex or as a 1957string; by default 1958.Xr pfctl 8 1959randomly generates a key for source-hash every time the 1960ruleset is reloaded. 1961.It Ar round-robin 1962The 1963.Ar round-robin 1964option loops through the redirection address(es). 1965.Pp 1966When more than one redirection address is specified, 1967.Ar round-robin 1968is the only permitted pool type. 1969.It Ar static-port 1970With 1971.Ar nat 1972rules, the 1973.Ar static-port 1974option prevents 1975.Xr pf 4 1976from modifying the source port on TCP and UDP packets. 1977.El 1978.Pp 1979Additionally, the 1980.Ar sticky-address 1981option can be specified to help ensure that multiple connections from the 1982same source are mapped to the same redirection address. 1983This option can be used with the 1984.Ar random 1985and 1986.Ar round-robin 1987pool options. 1988Note that by default these associations are destroyed as soon as there are 1989no longer states which refer to them; in order to make the mappings last 1990beyond the lifetime of the states, increase the global options with 1991.Ar set timeout src.track . 1992See 1993.Sx STATEFUL TRACKING OPTIONS 1994for more ways to control the source tracking. 1995.Sh STATE MODULATION 1996Much of the security derived from TCP is attributable to how well the 1997initial sequence numbers (ISNs) are chosen. 1998Some popular stack implementations choose 1999.Em very 2000poor ISNs and thus are normally susceptible to ISN prediction exploits. 2001By applying a 2002.Ar modulate state 2003rule to a TCP connection, 2004.Xr pf 4 2005will create a high quality random sequence number for each connection 2006endpoint. 2007.Pp 2008The 2009.Ar modulate state 2010directive implicitly keeps state on the rule and is 2011only applicable to TCP connections. 2012.Pp 2013For instance: 2014.Bd -literal -offset indent 2015block all 2016pass out proto tcp from any to any modulate state 2017pass in proto tcp from any to any port 25 flags S/SFRA modulate state 2018.Ed 2019.Pp 2020Note that modulated connections will not recover when the state table 2021is lost (firewall reboot, flushing the state table, etc...). 2022.Xr pf 4 2023will not be able to infer a connection again after the state table flushes 2024the connection's modulator. 2025When the state is lost, the connection may be left dangling until the 2026respective endpoints time out the connection. 2027It is possible on a fast local network for the endpoints to start an ACK 2028storm while trying to resynchronize after the loss of the modulator. 2029The default 2030.Ar flags 2031settings (or a more strict equivalent) should be used on 2032.Ar modulate state 2033rules to prevent ACK storms. 2034.Pp 2035Note that alternative methods are available 2036to prevent loss of the state table 2037and allow for firewall failover. 2038See 2039.Xr carp 4 2040and 2041.Xr pfsync 4 2042for further information. 2043.Sh SYN PROXY 2044By default, 2045.Xr pf 4 2046passes packets that are part of a 2047.Xr tcp 4 2048handshake between the endpoints. 2049The 2050.Ar synproxy state 2051option can be used to cause 2052.Xr pf 4 2053itself to complete the handshake with the active endpoint, perform a handshake 2054with the passive endpoint, and then forward packets between the endpoints. 2055.Pp 2056No packets are sent to the passive endpoint before the active endpoint has 2057completed the handshake, hence so-called SYN floods with spoofed source 2058addresses will not reach the passive endpoint, as the sender can't complete the 2059handshake. 2060.Pp 2061The proxy is transparent to both endpoints, they each see a single 2062connection from/to the other endpoint. 2063.Xr pf 4 2064chooses random initial sequence numbers for both handshakes. 2065Once the handshakes are completed, the sequence number modulators 2066(see previous section) are used to translate further packets of the 2067connection. 2068.Ar synproxy state 2069includes 2070.Ar modulate state . 2071.Pp 2072Rules with 2073.Ar synproxy 2074will not work if 2075.Xr pf 4 2076operates on a 2077.Xr bridge 4 . 2078.Pp 2079Example: 2080.Bd -literal -offset indent 2081pass in proto tcp from any to any port www synproxy state 2082.Ed 2083.Sh STATEFUL TRACKING OPTIONS 2084A number of options related to stateful tracking can be applied on a 2085per-rule basis. 2086.Ar keep state , 2087.Ar modulate state 2088and 2089.Ar synproxy state 2090support these options, and 2091.Ar keep state 2092must be specified explicitly to apply options to a rule. 2093.Pp 2094.Bl -tag -width xxxx -compact 2095.It Ar max Aq Ar number 2096Limits the number of concurrent states the rule may create. 2097When this limit is reached, further packets that would create 2098state will not match this rule until existing states time out. 2099.It Ar no-sync 2100Prevent state changes for states created by this rule from appearing on the 2101.Xr pfsync 4 2102interface. 2103.It Xo Aq Ar timeout 2104.Aq Ar seconds 2105.Xc 2106Changes the timeout values used for states created by this rule. 2107For a list of all valid timeout names, see 2108.Sx OPTIONS 2109above. 2110.It Ar sloppy 2111Uses a sloppy TCP connection tracker that does not check sequence 2112numbers at all, which makes insertion and ICMP teardown attacks way 2113easier. 2114This is intended to be used in situations where one does not see all 2115packets of a connection, e.g. in asymmetric routing situations. 2116Cannot be used with modulate or synproxy state. 2117.It Ar pflow 2118States created by this rule are exported on the 2119.Xr pflow 4 2120interface. 2121.El 2122.Pp 2123Multiple options can be specified, separated by commas: 2124.Bd -literal -offset indent 2125pass in proto tcp from any to any \e 2126 port www keep state \e 2127 (max 100, source-track rule, max-src-nodes 75, \e 2128 max-src-states 3, tcp.established 60, tcp.closing 5) 2129.Ed 2130.Pp 2131When the 2132.Ar source-track 2133keyword is specified, the number of states per source IP is tracked. 2134.Pp 2135.Bl -tag -width xxxx -compact 2136.It Ar source-track rule 2137The maximum number of states created by this rule is limited by the rule's 2138.Ar max-src-nodes 2139and 2140.Ar max-src-states 2141options. 2142Only state entries created by this particular rule count toward the rule's 2143limits. 2144.It Ar source-track global 2145The number of states created by all rules that use this option is limited. 2146Each rule can specify different 2147.Ar max-src-nodes 2148and 2149.Ar max-src-states 2150options, however state entries created by any participating rule count towards 2151each individual rule's limits. 2152.El 2153.Pp 2154The following limits can be set: 2155.Pp 2156.Bl -tag -width xxxx -compact 2157.It Ar max-src-nodes Aq Ar number 2158Limits the maximum number of source addresses which can simultaneously 2159have state table entries. 2160.It Ar max-src-states Aq Ar number 2161Limits the maximum number of simultaneous state entries that a single 2162source address can create with this rule. 2163.El 2164.Pp 2165For stateful TCP connections, limits on established connections (connections 2166which have completed the TCP 3-way handshake) can also be enforced 2167per source IP. 2168.Pp 2169.Bl -tag -width xxxx -compact 2170.It Ar max-src-conn Aq Ar number 2171Limits the maximum number of simultaneous TCP connections which have 2172completed the 3-way handshake that a single host can make. 2173.It Xo Ar max-src-conn-rate Aq Ar number 2174.No / Aq Ar seconds 2175.Xc 2176Limit the rate of new connections over a time interval. 2177The connection rate is an approximation calculated as a moving average. 2178.El 2179.Pp 2180Because the 3-way handshake ensures that the source address is not being 2181spoofed, more aggressive action can be taken based on these limits. 2182With the 2183.Ar overload Aq Ar table 2184state option, source IP addresses which hit either of the limits on 2185established connections will be added to the named table. 2186This table can be used in the ruleset to block further activity from 2187the offending host, redirect it to a tarpit process, or restrict its 2188bandwidth. 2189.Pp 2190The optional 2191.Ar flush 2192keyword kills all states created by the matching rule which originate 2193from the host which exceeds these limits. 2194The 2195.Ar global 2196modifier to the flush command kills all states originating from the 2197offending host, regardless of which rule created the state. 2198.Pp 2199For example, the following rules will protect the webserver against 2200hosts making more than 100 connections in 10 seconds. 2201Any host which connects faster than this rate will have its address added 2202to the 2203.Aq bad_hosts 2204table and have all states originating from it flushed. 2205Any new packets arriving from this host will be dropped unconditionally 2206by the block rule. 2207.Bd -literal -offset indent 2208block quick from \*(Ltbad_hosts\*(Gt 2209pass in on $ext_if proto tcp to $webserver port www keep state \e 2210 (max-src-conn-rate 100/10, overload \*(Ltbad_hosts\*(Gt flush global) 2211.Ed 2212.Sh OPERATING SYSTEM FINGERPRINTING 2213Passive OS Fingerprinting is a mechanism to inspect nuances of a TCP 2214connection's initial SYN packet and guess at the host's operating system. 2215Unfortunately these nuances are easily spoofed by an attacker so the 2216fingerprint is not useful in making security decisions. 2217But the fingerprint is typically accurate enough to make policy decisions 2218upon. 2219.Pp 2220The fingerprints may be specified by operating system class, by 2221version, or by subtype/patchlevel. 2222The class of an operating system is typically the vendor or genre 2223and would be 2224.Ox 2225for the 2226.Xr pf 4 2227firewall itself. 2228The version of the oldest available 2229.Ox 2230release on the main FTP site 2231would be 2.6 and the fingerprint would be written 2232.Pp 2233.Dl \&"OpenBSD 2.6\&" 2234.Pp 2235The subtype of an operating system is typically used to describe the 2236patchlevel if that patch led to changes in the TCP stack behavior. 2237In the case of 2238.Ox , 2239the only subtype is for a fingerprint that was 2240normalized by the 2241.Ar no-df 2242scrub option and would be specified as 2243.Pp 2244.Dl \&"OpenBSD 3.3 no-df\&" 2245.Pp 2246Fingerprints for most popular operating systems are provided by 2247.Xr pf.os 5 . 2248Once 2249.Xr pf 4 2250is running, a complete list of known operating system fingerprints may 2251be listed by running: 2252.Pp 2253.Dl # pfctl -so 2254.Pp 2255Filter rules can enforce policy at any level of operating system specification 2256assuming a fingerprint is present. 2257Policy could limit traffic to approved operating systems or even ban traffic 2258from hosts that aren't at the latest service pack. 2259.Pp 2260The 2261.Ar unknown 2262class can also be used as the fingerprint which will match packets for 2263which no operating system fingerprint is known. 2264.Pp 2265Examples: 2266.Bd -literal -offset indent 2267pass out proto tcp from any os OpenBSD 2268block out proto tcp from any os Doors 2269block out proto tcp from any os "Doors PT" 2270block out proto tcp from any os "Doors PT SP3" 2271block out from any os "unknown" 2272pass on lo0 proto tcp from any os "OpenBSD 3.3 lo0" 2273.Ed 2274.Pp 2275Operating system fingerprinting is limited only to the TCP SYN packet. 2276This means that it will not work on other protocols and will not match 2277a currently established connection. 2278.Pp 2279Caveat: operating system fingerprints are occasionally wrong. 2280There are three problems: an attacker can trivially craft his packets to 2281appear as any operating system he chooses; 2282an operating system patch could change the stack behavior and no fingerprints 2283will match it until the database is updated; 2284and multiple operating systems may have the same fingerprint. 2285.Sh BLOCKING SPOOFED TRAFFIC 2286"Spoofing" is the faking of IP addresses, typically for malicious 2287purposes. 2288The 2289.Ar antispoof 2290directive expands to a set of filter rules which will block all 2291traffic with a source IP from the network(s) directly connected 2292to the specified interface(s) from entering the system through 2293any other interface. 2294.Pp 2295For example, the line 2296.Bd -literal -offset indent 2297antispoof for lo0 2298.Ed 2299.Pp 2300expands to 2301.Bd -literal -offset indent 2302block drop in on ! lo0 inet from 127.0.0.1/8 to any 2303block drop in on ! lo0 inet6 from ::1 to any 2304.Ed 2305.Pp 2306For non-loopback interfaces, there are additional rules to block incoming 2307packets with a source IP address identical to the interface's IP(s). 2308For example, assuming the interface wi0 had an IP address of 10.0.0.1 and a 2309netmask of 255.255.255.0, 2310the line 2311.Bd -literal -offset indent 2312antispoof for wi0 inet 2313.Ed 2314.Pp 2315expands to 2316.Bd -literal -offset indent 2317block drop in on ! wi0 inet from 10.0.0.0/24 to any 2318block drop in inet from 10.0.0.1 to any 2319.Ed 2320.Pp 2321Caveat: Rules created by the 2322.Ar antispoof 2323directive interfere with packets sent over loopback interfaces 2324to local addresses. 2325One should pass these explicitly. 2326.Sh FRAGMENT HANDLING 2327The size of IP datagrams (packets) can be significantly larger than the 2328maximum transmission unit (MTU) of the network. 2329In cases when it is necessary or more efficient to send such large packets, 2330the large packet will be fragmented into many smaller packets that will each 2331fit onto the wire. 2332Unfortunately for a firewalling device, only the first logical fragment will 2333contain the necessary header information for the subprotocol that allows 2334.Xr pf 4 2335to filter on things such as TCP ports or to perform NAT. 2336.Pp 2337Besides the use of 2338.Ar scrub 2339rules as described in 2340.Sx TRAFFIC NORMALIZATION 2341above, there are three options for handling fragments in the packet filter. 2342.Pp 2343One alternative is to filter individual fragments with filter rules. 2344If no 2345.Ar scrub 2346rule applies to a fragment, it is passed to the filter. 2347Filter rules with matching IP header parameters decide whether the 2348fragment is passed or blocked, in the same way as complete packets 2349are filtered. 2350Without reassembly, fragments can only be filtered based on IP header 2351fields (source/destination address, protocol), since subprotocol header 2352fields are not available (TCP/UDP port numbers, ICMP code/type). 2353The 2354.Ar fragment 2355option can be used to restrict filter rules to apply only to 2356fragments, but not complete packets. 2357Filter rules without the 2358.Ar fragment 2359option still apply to fragments, if they only specify IP header fields. 2360For instance, the rule 2361.Bd -literal -offset indent 2362pass in proto tcp from any to any port 80 2363.Ed 2364.Pp 2365never applies to a fragment, even if the fragment is part of a TCP 2366packet with destination port 80, because without reassembly this information 2367is not available for each fragment. 2368This also means that fragments cannot create new or match existing 2369state table entries, which makes stateful filtering and address 2370translation (NAT, redirection) for fragments impossible. 2371.Pp 2372It's also possible to reassemble only certain fragments by specifying 2373source or destination addresses or protocols as parameters in 2374.Ar scrub 2375rules. 2376.Pp 2377In most cases, the benefits of reassembly outweigh the additional 2378memory cost, and it's recommended to use 2379.Ar scrub 2380rules to reassemble 2381all fragments via the 2382.Ar fragment reassemble 2383modifier. 2384.Pp 2385The memory allocated for fragment caching can be limited using 2386.Xr pfctl 8 . 2387Once this limit is reached, fragments that would have to be cached 2388are dropped until other entries time out. 2389The timeout value can also be adjusted. 2390.Pp 2391Currently, only IPv4 fragments are supported and IPv6 fragments 2392are blocked unconditionally. 2393.Sh ANCHORS 2394Besides the main ruleset, 2395.Xr pfctl 8 2396can load rulesets into 2397.Ar anchor 2398attachment points. 2399An 2400.Ar anchor 2401is a container that can hold rules, address tables, and other anchors. 2402.Pp 2403An 2404.Ar anchor 2405has a name which specifies the path where 2406.Xr pfctl 8 2407can be used to access the anchor to perform operations on it, such as 2408attaching child anchors to it or loading rules into it. 2409Anchors may be nested, with components separated by 2410.Sq / 2411characters, similar to how file system hierarchies are laid out. 2412The main ruleset is actually the default anchor, so filter and 2413translation rules, for example, may also be contained in any anchor. 2414.Pp 2415An anchor can reference another 2416.Ar anchor 2417attachment point 2418using the following kinds 2419of rules: 2420.Bl -tag -width xxxx 2421.It Ar nat-anchor Aq Ar name 2422Evaluates the 2423.Ar nat 2424rules in the specified 2425.Ar anchor . 2426.It Ar rdr-anchor Aq Ar name 2427Evaluates the 2428.Ar rdr 2429rules in the specified 2430.Ar anchor . 2431.It Ar binat-anchor Aq Ar name 2432Evaluates the 2433.Ar binat 2434rules in the specified 2435.Ar anchor . 2436.It Ar anchor Aq Ar name 2437Evaluates the filter rules in the specified 2438.Ar anchor . 2439.It Xo Ar load anchor 2440.Aq Ar name 2441.Ar from Aq Ar file 2442.Xc 2443Loads the rules from the specified file into the 2444anchor 2445.Ar name . 2446.El 2447.Pp 2448When evaluation of the main ruleset reaches an 2449.Ar anchor 2450rule, 2451.Xr pf 4 2452will proceed to evaluate all rules specified in that anchor. 2453.Pp 2454Matching filter and translation rules marked with the 2455.Ar quick 2456option are final and abort the evaluation of the rules in other 2457anchors and the main ruleset. 2458If the 2459.Ar anchor 2460itself is marked with the 2461.Ar quick 2462option, 2463ruleset evaluation will terminate when the anchor is exited if the packet is 2464matched by any rule within the anchor. 2465.Pp 2466.Ar anchor 2467rules are evaluated relative to the anchor in which they are contained. 2468For example, all 2469.Ar anchor 2470rules specified in the main ruleset will reference anchor 2471attachment points underneath the main ruleset, and 2472.Ar anchor 2473rules specified in a file loaded from a 2474.Ar load anchor 2475rule will be attached under that anchor point. 2476.Pp 2477Rules may be contained in 2478.Ar anchor 2479attachment points which do not contain any rules when the main ruleset 2480is loaded, and later such anchors can be manipulated through 2481.Xr pfctl 8 2482without reloading the main ruleset or other anchors. 2483For example, 2484.Bd -literal -offset indent 2485ext_if = \&"kue0\&" 2486block on $ext_if all 2487anchor spam 2488pass out on $ext_if all 2489pass in on $ext_if proto tcp from any \e 2490 to $ext_if port smtp 2491.Ed 2492.Pp 2493blocks all packets on the external interface by default, then evaluates 2494all rules in the 2495.Ar anchor 2496named "spam", and finally passes all outgoing connections and 2497incoming connections to port 25. 2498.Bd -literal -offset indent 2499# echo \&"block in quick from 1.2.3.4 to any\&" \&| \e 2500 pfctl -a spam -f - 2501.Ed 2502.Pp 2503This loads a single rule into the 2504.Ar anchor , 2505which blocks all packets from a specific address. 2506.Pp 2507The anchor can also be populated by adding a 2508.Ar load anchor 2509rule after the 2510.Ar anchor 2511rule: 2512.Bd -literal -offset indent 2513anchor spam 2514load anchor spam from "/etc/pf-spam.conf" 2515.Ed 2516.Pp 2517When 2518.Xr pfctl 8 2519loads 2520.Nm pf.conf , 2521it will also load all the rules from the file 2522.Pa /etc/pf-spam.conf 2523into the anchor. 2524.Pp 2525Optionally, 2526.Ar anchor 2527rules can specify packet filtering parameters using the same syntax as 2528filter rules. 2529When parameters are used, the 2530.Ar anchor 2531rule is only evaluated for matching packets. 2532This allows conditional evaluation of anchors, like: 2533.Bd -literal -offset indent 2534block on $ext_if all 2535anchor spam proto tcp from any to any port smtp 2536pass out on $ext_if all 2537pass in on $ext_if proto tcp from any to $ext_if port smtp 2538.Ed 2539.Pp 2540The rules inside 2541.Ar anchor 2542spam are only evaluated for 2543.Ar tcp 2544packets with destination port 25. 2545Hence, 2546.Bd -literal -offset indent 2547# echo \&"block in quick from 1.2.3.4 to any" \&| \e 2548 pfctl -a spam -f - 2549.Ed 2550.Pp 2551will only block connections from 1.2.3.4 to port 25. 2552.Pp 2553Anchors may end with the asterisk 2554.Pq Sq * 2555character, which signifies that all anchors attached at that point 2556should be evaluated in the alphabetical ordering of their anchor name. 2557For example, 2558.Bd -literal -offset indent 2559anchor "spam/*" 2560.Ed 2561.Pp 2562will evaluate each rule in each anchor attached to the 2563.Li spam 2564anchor. 2565Note that it will only evaluate anchors that are directly attached to the 2566.Li spam 2567anchor, and will not descend to evaluate anchors recursively. 2568.Pp 2569Since anchors are evaluated relative to the anchor in which they are 2570contained, there is a mechanism for accessing the parent and ancestor 2571anchors of a given anchor. 2572Similar to file system path name resolution, if the sequence 2573.Dq .. 2574appears as an anchor path component, the parent anchor of the current 2575anchor in the path evaluation at that point will become the new current 2576anchor. 2577As an example, consider the following: 2578.Bd -literal -offset indent 2579# echo ' anchor "spam/allowed" ' | pfctl -f - 2580# echo -e ' anchor "../banned" \en pass' | \e 2581 pfctl -a spam/allowed -f - 2582.Ed 2583.Pp 2584Evaluation of the main ruleset will lead into the 2585.Li spam/allowed 2586anchor, which will evaluate the rules in the 2587.Li spam/banned 2588anchor, if any, before finally evaluating the 2589.Ar pass 2590rule. 2591.Pp 2592Filter rule 2593.Ar anchors 2594can also be loaded inline in the ruleset within a brace ('{' '}') delimited 2595block. 2596Brace delimited blocks may contain rules or other brace-delimited blocks. 2597When anchors are loaded this way the anchor name becomes optional. 2598.Bd -literal -offset indent 2599anchor "external" on egress { 2600 block 2601 anchor out { 2602 pass proto tcp from any to port { 25, 80, 443 } 2603 } 2604 pass in proto tcp to any port 22 2605} 2606.Ed 2607.Pp 2608Since the parser specification for anchor names is a string, any 2609reference to an anchor name containing 2610.Sq / 2611characters will require double quote 2612.Pq Sq \&" 2613characters around the anchor name. 2614.Sh TRANSLATION EXAMPLES 2615This example maps incoming requests on port 80 to port 8080, on 2616which a daemon is running (because, for example, it is not run as root, 2617and therefore lacks permission to bind to port 80). 2618.Bd -literal 2619# use a macro for the interface name, so it can be changed easily 2620ext_if = \&"ne3\&" 2621 2622# map daemon on 8080 to appear to be on 80 2623rdr on $ext_if proto tcp from any to any port 80 -\*(Gt 127.0.0.1 port 8080 2624.Ed 2625.Pp 2626If the 2627.Ar pass 2628modifier is given, packets matching the translation rule are passed without 2629inspecting the filter rules: 2630.Bd -literal 2631rdr pass on $ext_if proto tcp from any to any port 80 -\*(Gt 127.0.0.1 \e 2632 port 8080 2633.Ed 2634.Pp 2635In the example below, vlan12 is configured as 192.168.168.1; 2636the machine translates all packets coming from 192.168.168.0/24 to 204.92.77.111 2637when they are going out any interface except vlan12. 2638This has the net effect of making traffic from the 192.168.168.0/24 2639network appear as though it is the Internet routable address 2640204.92.77.111 to nodes behind any interface on the router except 2641for the nodes on vlan12. 2642(Thus, 192.168.168.1 can talk to the 192.168.168.0/24 nodes.) 2643.Bd -literal 2644nat on ! vlan12 from 192.168.168.0/24 to any -\*(Gt 204.92.77.111 2645.Ed 2646.Pp 2647In the example below, the machine sits between a fake internal 144.19.74.* 2648network, and a routable external IP of 204.92.77.100. 2649The 2650.Ar no nat 2651rule excludes protocol AH from being translated. 2652.Bd -literal 2653# NO NAT 2654no nat on $ext_if proto ah from 144.19.74.0/24 to any 2655nat on $ext_if from 144.19.74.0/24 to any -\*(Gt 204.92.77.100 2656.Ed 2657.Pp 2658In the example below, packets bound for one specific server, as well as those 2659generated by the sysadmins are not proxied; all other connections are. 2660.Bd -literal 2661# NO RDR 2662no rdr on $int_if proto { tcp, udp } from any to $server port 80 2663no rdr on $int_if proto { tcp, udp } from $sysadmins to any port 80 2664rdr on $int_if proto { tcp, udp } from any to any port 80 -\*(Gt 127.0.0.1 \e 2665 port 80 2666.Ed 2667.Pp 2668This longer example uses both a NAT and a redirection. 2669The external interface has the address 157.161.48.183. 2670On localhost, we are running 2671.Xr ftp-proxy 8 , 2672waiting for FTP sessions to be redirected to it. 2673The three mandatory anchors for 2674.Xr ftp-proxy 8 2675are omitted from this example; see the 2676.Xr ftp-proxy 8 2677manpage. 2678.Bd -literal 2679# NAT 2680# Translate outgoing packets' source addresses (any protocol). 2681# In this case, any address but the gateway's external address is mapped. 2682nat on $ext_if inet from ! ($ext_if) to any -\*(Gt ($ext_if) 2683 2684# NAT PROXYING 2685# Map outgoing packets' source port to an assigned proxy port instead of 2686# an arbitrary port. 2687# In this case, proxy outgoing isakmp with port 500 on the gateway. 2688nat on $ext_if inet proto udp from any port = isakmp to any -\*(Gt ($ext_if) \e 2689 port 500 2690 2691# BINAT 2692# Translate outgoing packets' source address (any protocol). 2693# Translate incoming packets' destination address to an internal machine 2694# (bidirectional). 2695binat on $ext_if from 10.1.2.150 to any -\*(Gt $ext_if 2696 2697# RDR 2698# Translate incoming packets' destination addresses. 2699# As an example, redirect a TCP and UDP port to an internal machine. 2700rdr on $ext_if inet proto tcp from any to ($ext_if) port 8080 \e 2701 -\*(Gt 10.1.2.151 port 22 2702rdr on $ext_if inet proto udp from any to ($ext_if) port 8080 \e 2703 -\*(Gt 10.1.2.151 port 53 2704 2705# RDR 2706# Translate outgoing ftp control connections to send them to localhost 2707# for proxying with ftp-proxy(8) running on port 8021. 2708rdr on $int_if proto tcp from any to any port 21 -\*(Gt 127.0.0.1 port 8021 2709.Ed 2710.Pp 2711In this example, a NAT gateway is set up to translate internal addresses 2712using a pool of public addresses (192.0.2.16/28) and to redirect 2713incoming web server connections to a group of web servers on the internal 2714network. 2715.Bd -literal 2716# NAT LOAD BALANCE 2717# Translate outgoing packets' source addresses using an address pool. 2718# A given source address is always translated to the same pool address by 2719# using the source-hash keyword. 2720nat on $ext_if inet from any to any -\*(Gt 192.0.2.16/28 source-hash 2721 2722# RDR ROUND ROBIN 2723# Translate incoming web server connections to a group of web servers on 2724# the internal network. 2725rdr on $ext_if proto tcp from any to any port 80 \e 2726 -\*(Gt { 10.1.2.155, 10.1.2.160, 10.1.2.161 } round-robin 2727.Ed 2728.Sh FILTER EXAMPLES 2729.Bd -literal 2730# The external interface is kue0 2731# (157.161.48.183, the only routable address) 2732# and the private network is 10.0.0.0/8, for which we are doing NAT. 2733 2734# use a macro for the interface name, so it can be changed easily 2735ext_if = \&"kue0\&" 2736 2737# normalize all incoming traffic 2738scrub in on $ext_if all fragment reassemble 2739 2740# block and log everything by default 2741block return log on $ext_if all 2742 2743# block anything coming from source we have no back routes for 2744block in from no-route to any 2745 2746# block packets whose ingress interface does not match the one in 2747# the route back to their source address 2748block in from urpf-failed to any 2749 2750# block and log outgoing packets that do not have our address as source, 2751# they are either spoofed or something is misconfigured (NAT disabled, 2752# for instance), we want to be nice and do not send out garbage. 2753block out log quick on $ext_if from ! 157.161.48.183 to any 2754 2755# silently drop broadcasts (cable modem noise) 2756block in quick on $ext_if from any to 255.255.255.255 2757 2758# block and log incoming packets from reserved address space and invalid 2759# addresses, they are either spoofed or misconfigured, we cannot reply to 2760# them anyway (hence, no return-rst). 2761block in log quick on $ext_if from { 10.0.0.0/8, 172.16.0.0/12, \e 2762 192.168.0.0/16, 255.255.255.255/32 } to any 2763 2764# ICMP 2765 2766# pass out/in certain ICMP queries and keep state (ping) 2767# state matching is done on host addresses and ICMP id (not type/code), 2768# so replies (like 0/0 for 8/0) will match queries 2769# ICMP error messages (which always refer to a TCP/UDP packet) are 2770# handled by the TCP/UDP states 2771pass on $ext_if inet proto icmp all icmp-type 8 code 0 2772 2773# UDP 2774 2775# pass out all UDP connections and keep state 2776pass out on $ext_if proto udp all 2777 2778# pass in certain UDP connections and keep state (DNS) 2779pass in on $ext_if proto udp from any to any port domain 2780 2781# TCP 2782 2783# pass out all TCP connections and modulate state 2784pass out on $ext_if proto tcp all modulate state 2785 2786# pass in certain TCP connections and keep state (SSH, SMTP, DNS, IDENT) 2787pass in on $ext_if proto tcp from any to any port { ssh, smtp, domain, \e 2788 auth } 2789 2790# Do not allow Windows 9x SMTP connections since they are typically 2791# a viral worm. Alternately we could limit these OSes to 1 connection each. 2792block in on $ext_if proto tcp from any os {"Windows 95", "Windows 98"} \e 2793 to any port smtp 2794 2795# IPv6 2796# pass in/out all IPv6 traffic: note that we have to enable this in two 2797# different ways, on both our physical interface and our tunnel 2798pass quick on gif0 inet6 2799pass quick on $ext_if proto ipv6 2800 2801# Packet Tagging 2802 2803# three interfaces: $int_if, $ext_if, and $wifi_if (wireless). NAT is 2804# being done on $ext_if for all outgoing packets. tag packets in on 2805# $int_if and pass those tagged packets out on $ext_if. all other 2806# outgoing packets (i.e., packets from the wireless network) are only 2807# permitted to access port 80. 2808 2809pass in on $int_if from any to any tag INTNET 2810pass in on $wifi_if from any to any 2811 2812block out on $ext_if from any to any 2813pass out quick on $ext_if tagged INTNET 2814pass out on $ext_if proto tcp from any to any port 80 2815 2816# tag incoming packets as they are redirected to spamd(8). use the tag 2817# to pass those packets through the packet filter. 2818 2819rdr on $ext_if inet proto tcp from \*(Ltspammers\*(Gt to port smtp \e 2820 tag SPAMD -\*(Gt 127.0.0.1 port spamd 2821 2822block in on $ext_if 2823pass in on $ext_if inet proto tcp tagged SPAMD 2824.Ed 2825.Sh GRAMMAR 2826Syntax for 2827.Nm 2828in BNF: 2829.Bd -literal 2830line = ( option | pf-rule | nat-rule | binat-rule | rdr-rule | 2831 antispoof-rule | altq-rule | queue-rule | trans-anchors | 2832 anchor-rule | anchor-close | load-anchor | table-rule | 2833 include ) 2834 2835option = "set" ( [ "timeout" ( timeout | "{" timeout-list "}" ) ] | 2836 [ "ruleset-optimization" [ "none" | "basic" | "profile" ]] | 2837 [ "optimization" [ "default" | "normal" | 2838 "high-latency" | "satellite" | 2839 "aggressive" | "conservative" ] ] 2840 [ "limit" ( limit-item | "{" limit-list "}" ) ] | 2841 [ "loginterface" ( interface-name | "none" ) ] | 2842 [ "block-policy" ( "drop" | "return" ) ] | 2843 [ "state-policy" ( "if-bound" | "floating" ) ] 2844 [ "state-defaults" state-opts ] 2845 [ "require-order" ( "yes" | "no" ) ] 2846 [ "fingerprints" filename ] | 2847 [ "skip on" ifspec ] | 2848 [ "debug" ( "none" | "urgent" | "misc" | "loud" ) ] ) 2849 2850pf-rule = action [ ( "in" | "out" ) ] 2851 [ "log" [ "(" logopts ")"] ] [ "quick" ] 2852 [ "on" ifspec ] [ "fastroute" | route ] [ af ] [ protospec ] 2853 hosts [ filteropt-list ] 2854 2855logopts = logopt [ "," logopts ] 2856logopt = "all" | "user" | "to" interface-name 2857 2858filteropt-list = filteropt-list filteropt | filteropt 2859filteropt = user | group | flags | icmp-type | icmp6-type | "tos" tos | 2860 ( "no" | "keep" | "modulate" | "synproxy" ) "state" 2861 [ "(" state-opts ")" ] | 2862 "fragment" | "no-df" | "min-ttl" number | "set-tos" tos | 2863 "max-mss" number | "random-id" | "reassemble tcp" | 2864 fragmentation | "allow-opts" | 2865 "label" string | "tag" string | [ ! ] "tagged" string | 2866 "queue" ( string | "(" string [ [ "," ] string ] ")" ) | 2867 "rtable" number | "probability" number"%" 2868 2869nat-rule = [ "no" ] "nat" [ "pass" [ "log" [ "(" logopts ")" ] ] ] 2870 [ "on" ifspec ] [ af ] 2871 [ protospec ] hosts [ "tag" string ] [ "tagged" string ] 2872 [ "-\*(Gt" ( redirhost | "{" redirhost-list "}" ) 2873 [ portspec ] [ pooltype ] [ "static-port" ] ] 2874 2875binat-rule = [ "no" ] "binat" [ "pass" [ "log" [ "(" logopts ")" ] ] ] 2876 [ "on" interface-name ] [ af ] 2877 [ "proto" ( proto-name | proto-number ) ] 2878 "from" address [ "/" mask-bits ] "to" ipspec 2879 [ "tag" string ] [ "tagged" string ] 2880 [ "-\*(Gt" address [ "/" mask-bits ] ] 2881 2882rdr-rule = [ "no" ] "rdr" [ "pass" [ "log" [ "(" logopts ")" ] ] ] 2883 [ "on" ifspec ] [ af ] 2884 [ protospec ] hosts [ "tag" string ] [ "tagged" string ] 2885 [ "-\*(Gt" ( redirhost | "{" redirhost-list "}" ) 2886 [ portspec ] [ pooltype ] ] 2887 2888antispoof-rule = "antispoof" [ "log" ] [ "quick" ] 2889 "for" ifspec [ af ] [ "label" string ] 2890 2891table-rule = "table" "\*(Lt" string "\*(Gt" [ tableopts-list ] 2892tableopts-list = tableopts-list tableopts | tableopts 2893tableopts = "persist" | "const" | "counters" | "file" string | 2894 "{" [ tableaddr-list ] "}" 2895tableaddr-list = tableaddr-list [ "," ] tableaddr-spec | tableaddr-spec 2896tableaddr-spec = [ "!" ] tableaddr [ "/" mask-bits ] 2897tableaddr = hostname | ifspec | "self" | 2898 ipv4-dotted-quad | ipv6-coloned-hex 2899 2900altq-rule = "altq on" interface-name queueopts-list 2901 "queue" subqueue 2902queue-rule = "queue" string [ "on" interface-name ] queueopts-list 2903 subqueue 2904 2905anchor-rule = "anchor" [ string ] [ ( "in" | "out" ) ] [ "on" ifspec ] 2906 [ af ] [ protospec ] [ hosts ] [ filteropt-list ] [ "{" ] 2907 2908anchor-close = "}" 2909 2910trans-anchors = ( "nat-anchor" | "rdr-anchor" | "binat-anchor" ) string 2911 [ "on" ifspec ] [ af ] [ "proto" ] [ protospec ] [ hosts ] 2912 2913load-anchor = "load anchor" string "from" filename 2914 2915queueopts-list = queueopts-list queueopts | queueopts 2916queueopts = [ "bandwidth" bandwidth-spec ] | 2917 [ "qlimit" number ] | [ "tbrsize" number ] | 2918 [ "priority" number ] | [ schedulers ] 2919schedulers = ( cbq-def | priq-def | hfsc-def ) 2920bandwidth-spec = "number" ( "b" | "Kb" | "Mb" | "Gb" | "%" ) 2921 2922action = "pass" | "block" [ return ] | [ "no" ] "scrub" 2923return = "drop" | "return" | "return-rst" [ "( ttl" number ")" ] | 2924 "return-icmp" [ "(" icmpcode [ [ "," ] icmp6code ] ")" ] | 2925 "return-icmp6" [ "(" icmp6code ")" ] 2926icmpcode = ( icmp-code-name | icmp-code-number ) 2927icmp6code = ( icmp6-code-name | icmp6-code-number ) 2928 2929ifspec = ( [ "!" ] ( interface-name | interface-group ) ) | 2930 "{" interface-list "}" 2931interface-list = [ "!" ] ( interface-name | interface-group ) 2932 [ [ "," ] interface-list ] 2933route = ( "route-to" | "reply-to" | "dup-to" ) 2934 ( routehost | "{" routehost-list "}" ) 2935 [ pooltype ] 2936af = "inet" | "inet6" 2937 2938protospec = "proto" ( proto-name | proto-number | 2939 "{" proto-list "}" ) 2940proto-list = ( proto-name | proto-number ) [ [ "," ] proto-list ] 2941 2942hosts = "all" | 2943 "from" ( "any" | "no-route" | "urpf-failed" | "self" | host | 2944 "{" host-list "}" ) [ port ] [ os ] 2945 "to" ( "any" | "no-route" | "self" | host | 2946 "{" host-list "}" ) [ port ] 2947 2948ipspec = "any" | host | "{" host-list "}" 2949host = [ "!" ] ( address [ "/" mask-bits ] | "\*(Lt" string "\*(Gt" ) 2950redirhost = address [ "/" mask-bits ] 2951routehost = "(" interface-name [ address [ "/" mask-bits ] ] ")" 2952address = ( interface-name | interface-group | 2953 "(" ( interface-name | interface-group ) ")" | 2954 hostname | ipv4-dotted-quad | ipv6-coloned-hex ) 2955host-list = host [ [ "," ] host-list ] 2956redirhost-list = redirhost [ [ "," ] redirhost-list ] 2957routehost-list = routehost [ [ "," ] routehost-list ] 2958 2959port = "port" ( unary-op | binary-op | "{" op-list "}" ) 2960portspec = "port" ( number | name ) [ ":" ( "*" | number | name ) ] 2961os = "os" ( os-name | "{" os-list "}" ) 2962user = "user" ( unary-op | binary-op | "{" op-list "}" ) 2963group = "group" ( unary-op | binary-op | "{" op-list "}" ) 2964 2965unary-op = [ "=" | "!=" | "\*(Lt" | "\*(Le" | "\*(Gt" | "\*(Ge" ] 2966 ( name | number ) 2967binary-op = number ( "\*(Lt\*(Gt" | "\*(Gt\*(Lt" | ":" ) number 2968op-list = ( unary-op | binary-op ) [ [ "," ] op-list ] 2969 2970os-name = operating-system-name 2971os-list = os-name [ [ "," ] os-list ] 2972 2973flags = "flags" ( [ flag-set ] "/" flag-set | "any" ) 2974flag-set = [ "F" ] [ "S" ] [ "R" ] [ "P" ] [ "A" ] [ "U" ] [ "E" ] 2975 [ "W" ] 2976 2977icmp-type = "icmp-type" ( icmp-type-code | "{" icmp-list "}" ) 2978icmp6-type = "icmp6-type" ( icmp-type-code | "{" icmp-list "}" ) 2979icmp-type-code = ( icmp-type-name | icmp-type-number ) 2980 [ "code" ( icmp-code-name | icmp-code-number ) ] 2981icmp-list = icmp-type-code [ [ "," ] icmp-list ] 2982 2983tos = ( "lowdelay" | "throughput" | "reliability" | 2984 [ "0x" ] number ) 2985 2986state-opts = state-opt [ [ "," ] state-opts ] 2987state-opt = ( "max" number | "no-sync" | timeout | "sloppy" | "pflow" | 2988 "source-track" [ ( "rule" | "global" ) ] | 2989 "max-src-nodes" number | "max-src-states" number | 2990 "max-src-conn" number | 2991 "max-src-conn-rate" number "/" number | 2992 "overload" "\*(Lt" string "\*(Gt" [ "flush" ] | 2993 "if-bound" | "floating" ) 2994 2995fragmentation = [ "fragment reassemble" | "fragment crop" | 2996 "fragment drop-ovl" ] 2997 2998timeout-list = timeout [ [ "," ] timeout-list ] 2999timeout = ( "tcp.first" | "tcp.opening" | "tcp.established" | 3000 "tcp.closing" | "tcp.finwait" | "tcp.closed" | 3001 "udp.first" | "udp.single" | "udp.multiple" | 3002 "icmp.first" | "icmp.error" | 3003 "other.first" | "other.single" | "other.multiple" | 3004 "frag" | "interval" | "src.track" | 3005 "adaptive.start" | "adaptive.end" ) number 3006 3007limit-list = limit-item [ [ "," ] limit-list ] 3008limit-item = ( "states" | "frags" | "src-nodes" ) number 3009 3010pooltype = ( "bitmask" | "random" | 3011 "source-hash" [ ( hex-key | string-key ) ] | 3012 "round-robin" ) [ sticky-address ] 3013 3014subqueue = string | "{" queue-list "}" 3015queue-list = string [ [ "," ] string ] 3016cbq-def = "cbq" [ "(" cbq-opt [ [ "," ] cbq-opt ] ")" ] 3017priq-def = "priq" [ "(" priq-opt [ [ "," ] priq-opt ] ")" ] 3018hfsc-def = "hfsc" [ "(" hfsc-opt [ [ "," ] hfsc-opt ] ")" ] 3019cbq-opt = ( "default" | "borrow" | "red" | "ecn" | "rio" ) 3020priq-opt = ( "default" | "red" | "ecn" | "rio" ) 3021hfsc-opt = ( "default" | "red" | "ecn" | "rio" | 3022 linkshare-sc | realtime-sc | upperlimit-sc ) 3023linkshare-sc = "linkshare" sc-spec 3024realtime-sc = "realtime" sc-spec 3025upperlimit-sc = "upperlimit" sc-spec 3026sc-spec = ( bandwidth-spec | 3027 "(" bandwidth-spec number bandwidth-spec ")" ) 3028include = "include" filename 3029.Ed 3030.Sh FILES 3031.Bl -tag -width "/etc/protocols" -compact 3032.It Pa /etc/hosts 3033Host name database. 3034.It Pa /etc/pf.conf 3035Default location of the ruleset file. 3036.It Pa /etc/pf.os 3037Default location of OS fingerprints. 3038.It Pa /etc/protocols 3039Protocol name database. 3040.It Pa /etc/services 3041Service name database. 3042.El 3043.Sh SEE ALSO 3044.Xr altq 4 , 3045.Xr carp 4 , 3046.Xr icmp 4 , 3047.Xr icmp6 4 , 3048.Xr ip 4 , 3049.Xr ip6 4 , 3050.Xr pf 4 , 3051.Xr pflow 4 , 3052.Xr pfsync 4 , 3053.Xr tcp 4 , 3054.Xr udp 4 , 3055.Xr hosts 5 , 3056.Xr pf.os 5 , 3057.Xr protocols 5 , 3058.Xr services 5 , 3059.Xr ftp-proxy 8 , 3060.Xr pfctl 8 , 3061.Xr pflogd 8 , 3062.Sh HISTORY 3063The 3064.Nm 3065file format first appeared in 3066.Ox 3.0 . 3067