1.\" Copyright (c) 1985, 1988, 1991, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 3. Neither the name of the University nor the names of its contributors 13.\" may be used to endorse or promote products derived from this software 14.\" without specific prior written permission. 15.\" 16.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 17.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 20.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26.\" SUCH DAMAGE. 27.\" 28.\" @(#)ftpd.8 8.2 (Berkeley) 4/19/94 29.\" $FreeBSD: src/libexec/ftpd/ftpd.8,v 1.74 2007/04/20 09:08:20 trhodes Exp $ 30.\" $DragonFly: src/libexec/ftpd/ftpd.8,v 1.7 2008/05/02 02:05:04 swildner Exp $ 31.\" 32.Dd April 20, 2007 33.Dt FTPD 8 34.Os 35.Sh NAME 36.Nm ftpd 37.Nd Internet File Transfer Protocol server 38.Sh SYNOPSIS 39.Nm 40.Op Fl 468ADdEhMmOoRrSUvW 41.Op Fl l Op Fl l 42.Op Fl a Ar address 43.Op Fl H Ar host 44.Op Fl P Ar port 45.Op Fl p Ar file 46.Op Fl T Ar maxtimeout 47.Op Fl t Ar timeout 48.Op Fl u Ar umask 49.Sh DESCRIPTION 50The 51.Nm 52utility is the 53Internet File Transfer Protocol 54server process. 55The server uses the 56.Tn TCP 57protocol 58and listens at the port specified with the 59.Fl P 60option or in the 61.Dq ftp 62service specification; see 63.Xr services 5 . 64.Pp 65Available options: 66.Bl -tag -width indent 67.It Fl 4 68When 69.Fl D 70is specified, accept connections via 71.Dv AF_INET 72socket. 73.It Fl 6 74When 75.Fl D 76is specified, accept connections via 77.Dv AF_INET6 78socket. 79.It Fl 8 80Enable transparent UTF-8 mode. 81RFC\ 2640 compliant clients will be told that the character encoding 82used by the server is UTF-8, which is the only effect of the option. 83.Pp 84This option does not enable any encoding conversion for server file names; 85it implies instead that the names of files on the server are encoded 86in UTF-8. 87As for files uploaded via FTP, it is the duty of the RFC\ 2640 compliant 88client to convert their names from the client's local encoding to UTF-8. 89FTP command names and own 90.Nm 91messages are always encoded in ASCII, which is a subset of UTF-8. 92Hence no need for server-side conversion at all. 93.It Fl A 94Allow only anonymous ftp access. 95.It Fl a 96When 97.Fl D 98is specified, accept connections only on the specified 99.Ar address . 100.It Fl D 101With this option set, 102.Nm 103will detach and become a daemon, accepting connections on the FTP port and 104forking children processes to handle them. 105This is lower overhead than starting 106.Nm 107from 108.Xr inetd 8 109and is thus useful on busy servers to reduce load. 110.It Fl d 111Debugging information is written to the syslog using 112.Dv LOG_FTP . 113.It Fl E 114Disable the EPSV command. 115This is useful for servers behind older firewalls. 116.It Fl h 117Disable printing host-specific information, such as the 118server software version or hostname, in server messages. 119.It Fl H 120Advertise the hostname as 121.Ar host 122instead of using the value of 123.Xr gethostname 3 . 124.It Fl l 125Each successful and failed 126.Xr ftp 1 127session is logged using syslog with a facility of 128.Dv LOG_FTP . 129If this option is specified twice, the retrieve (get), store (put), append, 130delete, make directory, remove directory and rename operations and 131their filename arguments are also logged. 132By default, 133.Xr syslogd 8 134logs these to 135.Pa /var/log/xferlog . 136.It Fl M 137Prevent anonymous users from creating directories. 138.It Fl m 139Permit anonymous users to overwrite or modify 140existing files if allowed by file system permissions. 141By default, anonymous users cannot modify existing files; 142in particular, files to upload will be created under a unique name. 143.It Fl O 144Put server in write-only mode for anonymous users only. 145RETR is disabled for anonymous users, preventing anonymous downloads. 146This has no effect if 147.Fl o 148is also specified. 149.It Fl o 150Put server in write-only mode. 151RETR is disabled, preventing downloads. 152.It Fl P 153When 154.Fl D 155is specified, accept connections at 156.Ar port , 157specified as a numeric value or service name, instead of at the default 158.Dq ftp 159port. 160.It Fl p 161When 162.Fl D 163is specified, write the daemon's process ID to 164.Ar file 165instead of the default pid file, 166.Pa /var/run/ftpd.pid . 167.It Fl R 168With this option set, 169.Nm 170will revert to historical behavior with regard to security checks on 171user operations and restrictions on PORT requests. 172Currently, 173.Nm 174will only honor PORT commands directed to unprivileged ports on the 175remote user's host (which violates the FTP protocol specification but 176closes some security holes). 177.It Fl r 178Put server in read-only mode. 179All commands which may modify the local file system are disabled. 180.It Fl S 181With this option set, 182.Nm 183logs all anonymous file downloads to the file 184.Pa /var/log/ftpd 185when this file exists. 186.It Fl T 187A client may also request a different timeout period; 188the maximum period allowed may be set to 189.Ar timeout 190seconds with the 191.Fl T 192option. 193The default limit is 2 hours. 194.It Fl t 195The inactivity timeout period is set to 196.Ar timeout 197seconds (the default is 15 minutes). 198.It Fl U 199This option instructs ftpd to use data ports in the range of 200.Dv IP_PORTRANGE_DEFAULT 201instead of in the range of 202.Dv IP_PORTRANGE_HIGH . 203Such a change may be useful for some specific firewall configurations; 204see 205.Xr ip 4 206for more information. 207.Pp 208Note that option is a virtual no-op in 209.Fx 5.0 210and above; both port 211ranges are identical by default. 212.It Fl u 213The default file creation mode mask is set to 214.Ar umask , 215which is expected to be an octal numeric value. 216Refer to 217.Xr umask 2 218for details. 219This option may be overridden by 220.Xr login.conf 5 . 221.It Fl v 222A synonym for 223.Fl d . 224.It Fl W 225Do not log FTP sessions to 226.Pa /var/log/wtmp . 227.El 228.Pp 229The file 230.Pa /var/run/nologin 231can be used to disable ftp access. 232If the file exists, 233.Nm 234displays it and exits. 235If the file 236.Pa /etc/ftpwelcome 237exists, 238.Nm 239prints it before issuing the 240.Dq ready 241message. 242If the file 243.Pa /etc/ftpmotd 244exists, 245.Nm 246prints it after a successful login. 247Note the motd file used is the one 248relative to the login environment. 249This means the one in 250.Pa ~ftp/etc 251in the anonymous user's case. 252.Pp 253The ftp server currently supports the following ftp requests. 254The case of the requests is ignored. 255Requests marked [RW] are 256disabled if 257.Fl r 258is specified. 259.Bl -column "Request" -offset indent 260.It Sy Request Ta Sy "Description" 261.It ABOR Ta "abort previous command" 262.It ACCT Ta "specify account (ignored)" 263.It ALLO Ta "allocate storage (vacuously)" 264.It APPE Ta "append to a file [RW]" 265.It CDUP Ta "change to parent of current working directory" 266.It CWD Ta "change working directory" 267.It DELE Ta "delete a file [RW]" 268.It EPRT Ta "specify data connection port, multiprotocol" 269.It EPSV Ta "prepare for server-to-server transfer, multiprotocol" 270.It FEAT Ta "give information on extended features of server" 271.It HELP Ta "give help information" 272.It LIST Ta "give list files in a directory" Pq Dq Li "ls -lgA" 273.It LPRT Ta "specify data connection port, multiprotocol" 274.It LPSV Ta "prepare for server-to-server transfer, multiprotocol" 275.It MDTM Ta "show last modification time of file" 276.It MKD Ta "make a directory [RW]" 277.It MODE Ta "specify data transfer" Em mode 278.It NLST Ta "give name list of files in directory" 279.It NOOP Ta "do nothing" 280.It PASS Ta "specify password" 281.It PASV Ta "prepare for server-to-server transfer" 282.It PORT Ta "specify data connection port" 283.It PWD Ta "print the current working directory" 284.It QUIT Ta "terminate session" 285.It REST Ta "restart incomplete transfer" 286.It RETR Ta "retrieve a file" 287.It RMD Ta "remove a directory [RW]" 288.It RNFR Ta "specify rename-from file name [RW]" 289.It RNTO Ta "specify rename-to file name [RW]" 290.It SITE Ta "non-standard commands (see next section)" 291.It SIZE Ta "return size of file" 292.It STAT Ta "return status of server" 293.It STOR Ta "store a file [RW]" 294.It STOU Ta "store a file with a unique name [RW]" 295.It STRU Ta "specify data transfer" Em structure 296.It SYST Ta "show operating system type of server system" 297.It TYPE Ta "specify data transfer" Em type 298.It USER Ta "specify user name" 299.It XCUP Ta "change to parent of current working directory (deprecated)" 300.It XCWD Ta "change working directory (deprecated)" 301.It XMKD Ta "make a directory (deprecated) [RW]" 302.It XPWD Ta "print the current working directory (deprecated)" 303.It XRMD Ta "remove a directory (deprecated) [RW]" 304.El 305.Pp 306The following non-standard or 307.Ux 308specific commands are supported 309by the 310SITE request. 311.Bl -column Request -offset indent 312.It Sy Request Ta Sy Description 313.It UMASK Ta change umask, e.g. ``SITE UMASK 002'' 314.It IDLE Ta set idle-timer, e.g. ``SITE IDLE 60'' 315.It CHMOD Ta "change mode of a file [RW], e.g. ``SITE CHMOD 755 filename''" 316.It MD5 Ta "report the files MD5 checksum, e.g. ``SITE MD5 filename''" 317.It HELP Ta give help information 318.El 319.Pp 320Note: SITE requests are disabled in case of anonymous logins. 321.Pp 322The remaining ftp requests specified in Internet RFC 959 323are 324recognized, but not implemented. 325MDTM and SIZE are not specified in RFC 959, but will appear in the 326next updated FTP RFC. 327To avoid possible denial-of-service attacks, SIZE requests against 328files larger than 10240 bytes will be denied if the current transfer 329type is ASCII. 330.Pp 331The ftp server will abort an active file transfer only when the 332ABOR 333command is preceded by a Telnet "Interrupt Process" (IP) 334signal and a Telnet "Synch" signal in the command Telnet stream, 335as described in Internet RFC 959. 336If a 337STAT 338command is received during a data transfer, preceded by a Telnet IP 339and Synch, transfer status will be returned. 340.Pp 341The 342.Nm 343utility interprets file names according to the 344.Dq globbing 345conventions used by 346.Xr csh 1 . 347This allows users to utilize the metacharacters 348.Dq Li \&*?[]{}~ . 349.Pp 350The 351.Nm 352utility authenticates users according to six rules. 353.Bl -enum -offset indent 354.It 355The login name must be in the password data base 356and not have a null password. 357In this case a password must be provided by the client before any 358file operations may be performed. 359If the user has an OPIE key, the response from a successful USER 360command will include an OPIE challenge. 361The client may choose to respond with a PASS command giving either 362a standard password or an OPIE one-time password. 363The server will automatically determine which type of 364password it has been given and attempt to authenticate accordingly. 365See 366.Xr opie 4 367for more information on OPIE authentication. 368.It 369The login name must not appear in the file 370.Pa /etc/ftpusers . 371.It 372The login name must not be a member of a group specified in the file 373.Pa /etc/ftpusers . 374Entries in this file interpreted as group names are prefixed by an "at" 375.Ql \&@ 376sign. 377.It 378The user must have a standard shell returned by 379.Xr getusershell 3 . 380.It 381If the user name appears in the file 382.Pa /etc/ftpchroot , 383or the user is a member of a group with a group entry in this file, 384i.e., one prefixed with 385.Ql \&@ , 386the session's root will be changed to the directory specified 387in this file or to the user's login directory by 388.Xr chroot 2 389as for an 390.Dq anonymous 391or 392.Dq ftp 393account (see next item). 394See 395.Xr ftpchroot 5 396for a detailed description of the format of this file. 397This facility may also be triggered by enabling the boolean "ftp-chroot" 398capability in 399.Xr login.conf 5 . 400However, the user must still supply a password. 401This feature is intended as a compromise between a fully anonymous 402account and a fully privileged account. 403The account should also be set up as for an anonymous account. 404.It 405If the user name is 406.Dq anonymous 407or 408.Dq ftp , 409an 410anonymous ftp account must be present in the password 411file (user 412.Dq ftp ) . 413In this case the user is allowed 414to log in by specifying any password (by convention an email address for 415the user should be used as the password). 416When the 417.Fl S 418option is set, all transfers are logged as well. 419.El 420.Pp 421In the last case, 422.Nm 423takes special measures to restrict the client's access privileges. 424The server performs a 425.Xr chroot 2 426to the home directory of the 427.Dq ftp 428user. 429As a special case if the 430.Dq ftp 431user's home directory pathname contains the 432.Pa /./ 433separator, 434.Nm 435uses its left-hand side as the name of the directory to do 436.Xr chroot 2 437to, and its right-hand side to change the current directory to afterwards. 438A typical example for this case would be 439.Pa /usr/local/ftp/./pub . 440In order that system security is not breached, it is recommended 441that the 442.Dq ftp 443subtree be constructed with care, following these rules: 444.Bl -tag -width "~ftp/pub" -offset indent 445.It Pa ~ftp 446Make the home directory owned by 447.Dq root 448and unwritable by anyone. 449.It Pa ~ftp/etc 450Make this directory owned by 451.Dq root 452and unwritable by anyone (mode 555). 453The files pwd.db (see 454.Xr passwd 5 ) 455and 456.Xr group 5 457must be present for the 458.Xr ls 1 459command to be able to produce owner names rather than numbers. 460The password field in 461.Xr passwd 5 462is not used, and should not contain real passwords. 463The file 464.Pa ftpmotd , 465if present, will be printed after a successful login. 466These files should be mode 444. 467.It Pa ~ftp/pub 468This directory and the subdirectories beneath it should be owned 469by the users and groups responsible for placing files in them, 470and be writable only by them (mode 755 or 775). 471They should 472.Em not 473be owned or writable by 474.Dq ftp 475or its group, otherwise guest users 476can fill the drive with unwanted files. 477.El 478.Pp 479If the system has multiple IP addresses, 480.Nm 481supports the idea of virtual hosts, which provides the ability to 482define multiple anonymous ftp areas, each one allocated to a different 483internet address. 484The file 485.Pa /etc/ftphosts 486contains information pertaining to each of the virtual hosts. 487Each host is defined on its own line which contains a number of 488fields separated by whitespace: 489.Bl -tag -offset indent -width hostname 490.It hostname 491Contains the hostname or IP address of the virtual host. 492.It user 493Contains a user record in the system password file. 494As with normal anonymous ftp, this user's access uid, gid and group 495memberships determine file access to the anonymous ftp area. 496The anonymous ftp area (to which any user is chrooted on login) 497is determined by the home directory defined for the account. 498User id and group for any ftp account may be the same as for the 499standard ftp user. 500.It statfile 501File to which all file transfers are logged, which 502defaults to 503.Pa /var/log/ftpd . 504.It welcome 505This file is the welcome message displayed before the server ready 506prompt. 507It defaults to 508.Pa /etc/ftpwelcome . 509.It motd 510This file is displayed after the user logs in. 511It defaults to 512.Pa /etc/ftpmotd . 513.El 514.Pp 515Lines beginning with a '#' are ignored and can be used to include 516comments. 517.Pp 518Defining a virtual host for the primary IP address or hostname 519changes the default for ftp logins to that address. 520The 'user', 'statfile', 'welcome' and 'motd' fields may be left 521blank, or a single hyphen '-' used to indicate that the default 522value is to be used. 523.Pp 524As with any anonymous login configuration, due care must be given 525to setup and maintenance to guard against security related problems. 526.Pp 527The 528.Nm 529utility has internal support for handling remote requests to list 530files, and will not execute 531.Pa /bin/ls 532in either a chrooted or non-chrooted environment. 533The 534.Pa ~/bin/ls 535executable need not be placed into the chrooted tree, nor need the 536.Pa ~/bin 537directory exist. 538.Sh FILES 539.Bl -tag -width ".Pa /var/run/ftpd.pid" -compact 540.It Pa /etc/ftpusers 541List of unwelcome/restricted users. 542.It Pa /etc/ftpchroot 543List of normal users who should be chroot'd. 544.It Pa /etc/ftphosts 545Virtual hosting configuration file. 546.It Pa /etc/ftpwelcome 547Welcome notice. 548.It Pa /etc/ftpmotd 549Welcome notice after login. 550.It Pa /var/run/ftpd.pid 551Default pid file for daemon mode. 552.It Pa /var/run/nologin 553Displayed and access refused. 554.It Pa /var/log/ftpd 555Log file for anonymous transfers. 556.It Pa /var/log/xferlog 557Default place for session logs. 558.El 559.Sh SEE ALSO 560.Xr ftp 1 , 561.Xr umask 2 , 562.Xr getusershell 3 , 563.Xr opie 4 , 564.Xr ftpchroot 5 , 565.Xr login.conf 5 , 566.Xr inetd 8 , 567.Xr syslogd 8 568.Sh HISTORY 569The 570.Nm 571utility appeared in 572.Bx 4.2 . 573IPv6 support was added in WIDE Hydrangea IPv6 stack kit. 574.Sh BUGS 575The server must run as the super-user 576to create sockets with privileged port numbers. 577It maintains 578an effective user id of the logged in user, reverting to 579the super-user only when binding addresses to sockets. 580The 581possible security holes have been extensively 582scrutinized, but are possibly incomplete. 583