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. All advertising materials mentioning features or use of this software 13.\" must display the following acknowledgement: 14.\" This product includes software developed by the University of 15.\" California, Berkeley and its contributors. 16.\" 4. Neither the name of the University nor the names of its contributors 17.\" may be used to endorse or promote products derived from this software 18.\" without specific prior written permission. 19.\" 20.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30.\" SUCH DAMAGE. 31.\" 32.\" @(#)ftpd.8 8.2 (Berkeley) 4/19/94 33.\" $FreeBSD: src/libexec/ftpd/ftpd.8,v 1.31.2.18 2003/02/11 14:28:28 yar Exp $ 34.\" 35.Dd January 27, 2000 36.Dt FTPD 8 37.Os 38.Sh NAME 39.Nm ftpd 40.Nd Internet File Transfer Protocol server 41.Sh SYNOPSIS 42.Nm 43.Op Fl 46AdDEhmMoOrRSUvW 44.Op Fl l Op Fl l 45.Op Fl a Ar address 46.Op Fl p Ar file 47.Op Fl P Ar port 48.Op Fl t Ar timeout 49.Op Fl T Ar maxtimeout 50.Op Fl u Ar umask 51.Sh DESCRIPTION 52.Nm Ftpd 53is the 54Internet File Transfer Protocol 55server process. The 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 IPv4 connections. 71When 72.Fl 6 73is also specified, accept IPv4 connection via 74.Dv AF_INET6 75socket. 76When 77.Fl 6 78is not specified, accept IPv4 connection via 79.Dv AF_INET 80socket. 81.It Fl 6 82When 83.Fl D 84is specified, accept connections via 85.Dv AF_INET6 86socket. 87.It Fl a 88When 89.Fl D 90is specified, accept connections only on the specified 91.Ar address . 92.It Fl A 93Allow only anonymous ftp access. 94.It Fl d 95Debugging information is written to the syslog using 96.Dv LOG_FTP . 97.It Fl D 98With this option set, 99.Nm 100will detach and become a daemon, accepting connections on the FTP port and 101forking children processes to handle them. 102This is lower overhead than starting 103.Nm 104from 105.Xr inetd 8 106and is thus useful on busy servers to reduce load. 107.It Fl E 108Disable the EPSV command. 109This is useful for servers behind older firewalls. 110.It Fl h 111Disable printing host-specific information, such as the 112server software version or hostname, in server messages. 113.It Fl l 114Each successful and failed 115.Xr ftp 1 116session is logged using syslog with a facility of 117.Dv LOG_FTP . 118If this option is specified twice, the retrieve (get), store (put), append, 119delete, make directory, remove directory and rename operations and 120their filename arguments are also logged. 121Note: 122.Dv LOG_FTP 123messages 124are not displayed by 125.Xr syslogd 8 126by default, and may have to be enabled in 127.Xr syslogd 8 Ns 's 128configuration file. 129.It Fl m 130Permit anonymous users to overwrite or modify 131existing files if allowed by filesystem permissions. 132By default, anonymous users cannot modify existing files; 133in particular, files to upload will be created under a unique name. 134.It Fl M 135Prevent anonymous users from creating directories. 136.It Fl o 137Put server in write-only mode. 138RETR is disabled, preventing downloads. 139.It Fl O 140Put server in write-only mode for anonymous users only. 141RETR is disabled for anonymous users, preventing anonymous downloads. 142This has no effect if 143.Fl o 144is also specified. 145.It Fl p 146When 147.Fl D 148is specified, write the daemon's process ID to 149.Ar file . 150.It Fl P 151When 152.Fl D 153is specified, accept connections at 154.Ar port , 155specified as a numeric value or service name, instead of at the default 156.Dq ftp 157port. 158.It Fl r 159Put server in read-only mode. 160All commands which may modify the local filesystem are disabled. 161.It Fl R 162With this option set, 163.Nm 164will revert to historical behavior with regard to security checks on 165user operations and restrictions on PORT requests. 166Currently, 167.Nm 168will only honor PORT commands directed to unprivileged ports on the 169remote user's host (which violates the FTP protocol specification but 170closes some security holes). 171.It Fl S 172With this option set, 173.Nm 174logs all anonymous file downloads to the file 175.Pa /var/log/ftpd 176when this file exists. 177.It Fl t 178The inactivity timeout period is set to 179.Ar timeout 180seconds (the default is 15 minutes). 181.It Fl T 182A client may also request a different timeout period; 183the maximum period allowed may be set to 184.Ar timeout 185seconds with the 186.Fl T 187option. 188The default limit is 2 hours. 189.It Fl u 190The default file creation mode mask is set to 191.Ar umask , 192which is expected to be an octal numeric value. 193Refer to 194.Xr umask 2 195for details. 196.It Fl U 197In previous versions of 198.Nm , 199when a passive mode client requested a data connection to the server, 200the server would use data ports in the range 1024..4999. Now, by default, 201the server will use data ports in the range 49152..65535. Specifying this 202option will revert to the old behavior. 203.It Fl v 204A synonym for 205.Fl d . 206.It Fl W 207Don't log FTP sessions to 208.Pa /var/log/wtmp . 209.El 210.Pp 211The file 212.Pa /var/run/nologin 213can be used to disable ftp access. 214If the file exists, 215.Nm 216displays it and exits. 217If the file 218.Pa /etc/ftpwelcome 219exists, 220.Nm 221prints it before issuing the 222.Dq ready 223message. 224If the file 225.Pa /etc/ftpmotd 226exists, 227.Nm 228prints it after a successful login. Note the motd file used is the one 229relative to the login environment. This means the one in 230.Pa ~ftp/etc 231in the anonymous user's case. 232.Pp 233The ftp server currently supports the following ftp requests. 234The case of the requests is ignored. Requests marked [RW] are 235disabled if 236.Fl r 237is specified. 238.Bl -column "Request" -offset indent 239.It Sy Request Ta Sy "Description" 240.It ABOR Ta "abort previous command" 241.It ACCT Ta "specify account (ignored)" 242.It ALLO Ta "allocate storage (vacuously)" 243.It APPE Ta "append to a file [RW]" 244.It CDUP Ta "change to parent of current working directory" 245.It CWD Ta "change working directory" 246.It DELE Ta "delete a file [RW]" 247.It EPRT Ta "specify data connection port, multiprotocol" 248.It EPSV Ta "prepare for server-to-server transfer, multiprotocol" 249.It HELP Ta "give help information" 250.It LIST Ta "give list files in a directory" Pq Dq Li "ls -lgA" 251.It LPRT Ta "specify data connection port, multiprotocol" 252.It LPSV Ta "prepare for server-to-server transfer, multiprotocol" 253.It MDTM Ta "show last modification time of file" 254.It MKD Ta "make a directory [RW]" 255.It MODE Ta "specify data transfer" Em mode 256.It NLST Ta "give name list of files in directory" 257.It NOOP Ta "do nothing" 258.It PASS Ta "specify password" 259.It PASV Ta "prepare for server-to-server transfer" 260.It PORT Ta "specify data connection port" 261.It PWD Ta "print the current working directory" 262.It QUIT Ta "terminate session" 263.It REST Ta "restart incomplete transfer" 264.It RETR Ta "retrieve a file" 265.It RMD Ta "remove a directory [RW]" 266.It RNFR Ta "specify rename-from file name [RW]" 267.It RNTO Ta "specify rename-to file name [RW]" 268.It SITE Ta "non-standard commands (see next section)" 269.It SIZE Ta "return size of file" 270.It STAT Ta "return status of server" 271.It STOR Ta "store a file [RW]" 272.It STOU Ta "store a file with a unique name [RW]" 273.It STRU Ta "specify data transfer" Em structure 274.It SYST Ta "show operating system type of server system" 275.It TYPE Ta "specify data transfer" Em type 276.It USER Ta "specify user name" 277.It XCUP Ta "change to parent of current working directory (deprecated)" 278.It XCWD Ta "change working directory (deprecated)" 279.It XMKD Ta "make a directory (deprecated) [RW]" 280.It XPWD Ta "print the current working directory (deprecated)" 281.It XRMD Ta "remove a directory (deprecated) [RW]" 282.El 283.Pp 284The following non-standard or 285.Tn UNIX 286specific commands are supported 287by the 288SITE request. 289.Pp 290.Bl -column Request -offset indent 291.It Sy Request Ta Sy Description 292.It UMASK Ta change umask, e.g. ``SITE UMASK 002'' 293.It IDLE Ta set idle-timer, e.g. ``SITE IDLE 60'' 294.It CHMOD Ta "change mode of a file [RW], e.g. ``SITE CHMOD 755 filename''" 295.It MD5 Ta "report the files MD5 checksum, e.g. ``SITE MD5 filename''" 296.It HELP Ta give help information 297.El 298.Pp 299Note: SITE requests are disabled in case of anonymous logins. 300.Pp 301The remaining ftp requests specified in Internet RFC 959 302are 303recognized, but not implemented. 304MDTM and SIZE are not specified in RFC 959, but will appear in the 305next updated FTP RFC. 306To avoid possible denial-of-service attacks, SIZE requests against 307files larger than 10240 bytes will be denied if the current transfer 308type is ASCII. 309.Pp 310The ftp server will abort an active file transfer only when the 311ABOR 312command is preceded by a Telnet "Interrupt Process" (IP) 313signal and a Telnet "Synch" signal in the command Telnet stream, 314as described in Internet RFC 959. 315If a 316STAT 317command is received during a data transfer, preceded by a Telnet IP 318and Synch, transfer status will be returned. 319.Pp 320.Nm Ftpd 321interprets file names according to the 322.Dq globbing 323conventions used by 324.Xr csh 1 . 325This allows users to utilize the metacharacters 326.Dq Li \&*?[]{}~ . 327.Pp 328.Nm Ftpd 329authenticates users according to six rules. 330.Pp 331.Bl -enum -offset indent 332.It 333The login name must be in the password data base 334and not have a null password. 335In this case a password must be provided by the client before any 336file operations may be performed. 337If the user has an S/Key key, the response from a successful USER 338command will include an S/Key challenge. 339The client may choose to respond with a PASS command giving either 340a standard password or an S/Key one-time password. 341The server will automatically determine which type of 342password it has been given and attempt to authenticate accordingly. 343See 344.Xr key 1 345for more information on S/Key authentication. 346S/Key is a Trademark of Bellcore. 347.It 348The login name must not appear in the file 349.Pa /etc/ftpusers . 350.It 351The login name must not be a member of a group specified in the file 352.Pa /etc/ftpusers . 353Entries in this file interpreted as group names are prefixed by an "at" 354.Ql \&@ 355sign. 356.It 357The user must have a standard shell returned by 358.Xr getusershell 3 . 359.It 360If the user name appears in the file 361.Pa /etc/ftpchroot , 362or the user is a member of a group with a group entry in this file, 363i.e. one prefixed with 364.Ql \&@ , 365the session's root will be changed to the directory specified 366in this file or to the user's login directory by 367.Xr chroot 2 368as for an 369.Dq anonymous 370or 371.Dq ftp 372account (see next item). 373See 374.Xr ftpchroot 5 375for a detailed description of the format of this file. 376This facility may also be triggered by enabling the boolean "ftp-chroot" 377capability in 378.Xr login.conf 5 . 379However, the user must still supply a password. 380This feature is intended as a compromise between a fully anonymous 381account and a fully privileged account. 382The account should also be set up as for an anonymous account. 383.It 384If the user name is 385.Dq anonymous 386or 387.Dq ftp , 388an 389anonymous ftp account must be present in the password 390file (user 391.Dq ftp ) . 392In this case the user is allowed 393to log in by specifying any password (by convention an email address for 394the user should be used as the password). 395When the 396.Fl S 397option is set, all transfers are logged as well. 398.El 399.Pp 400In the last case, 401.Nm 402takes special measures to restrict the client's access privileges. 403The server performs a 404.Xr chroot 2 405to the home directory of the 406.Dq ftp 407user. 408As a special case if the 409.Dq ftp 410user's home directory pathname contains the 411.Dq \&/./ 412separator, 413.Nm 414uses its left-hand side as the name of the directory to do 415.Xr chroot 2 416to, and its right-hand side to change the current directory to afterwards. 417A typical example for this case would be 418.Pa /usr/local/ftp/./pub . 419In order that system security is not breached, it is recommended 420that the 421.Dq ftp 422subtree be constructed with care, following these rules: 423.Bl -tag -width "~ftp/pub" -offset indent 424.It Pa ~ftp 425Make the home directory owned by 426.Dq root 427and unwritable by anyone. 428.It Pa ~ftp/etc 429Make this directory owned by 430.Dq root 431and unwritable by anyone (mode 555). 432The files pwd.db (see 433.Xr passwd 5 ) 434and 435.Xr group 5 436must be present for the 437.Xr ls 438command to be able to produce owner names rather than numbers. 439The password field in 440.Xr passwd 441is not used, and should not contain real passwords. 442The file 443.Pa ftpmotd , 444if present, will be printed after a successful login. 445These files should be mode 444. 446.It Pa ~ftp/pub 447This directory and the subdirectories beneath it should be owned 448by the users and groups responsible for placing files in them, 449and be writable only by them (mode 755 or 775). 450They should 451.Em not 452be owned or writable by 453.Dq ftp 454or its group, otherwise guest users 455can fill the drive with unwanted files. 456.El 457.Pp 458If the system has multiple IP addresses, 459.Nm 460supports the idea of virtual hosts, which provides the ability to 461define multiple anonymous ftp areas, each one allocated to a different 462internet address. 463The file 464.Pa /etc/ftphosts 465contains information pertaining to each of the virtual hosts. 466Each host is defined on its own line which contains a number of 467fields separated by whitespace: 468.Bl -tag -offset indent -width hostname 469.It hostname 470Contains the hostname or IP address of the virtual host. 471.It user 472Contains a user record in the system password file. 473As with normal anonymous ftp, this user's access uid, gid and group 474memberships determine file access to the anonymous ftp area. 475The anonymous ftp area (to which any user is chrooted on login) 476is determined by the home directory defined for the account. 477User id and group for any ftp account may be the same as for the 478standard ftp user. 479.It statfile 480File to which all file transfers are logged, which 481defaults to 482.Pa /var/log/ftpd . 483.It welcome 484This file is the welcome message displayed before the server ready 485prompt. 486It defaults to 487.Pa /etc/ftpwelcome . 488.It motd 489This file is displayed after the user logs in. 490It defaults to 491.Pa /etc/ftpmotd . 492.El 493.Pp 494Lines beginning with a '#' are ignored and can be used to include 495comments. 496.Pp 497Defining a virtual host for the primary IP address or hostname 498changes the default for ftp logins to that address. 499The 'user', 'statfile', 'welcome' and 'motd' fields may be left 500blank, or a single hyphen '-' used to indicate that the default 501value is to be used. 502.Pp 503As with any anonymous login configuration, due care must be given 504to setup and maintenance to guard against security related problems. 505.Pp 506.Nm 507has internal support for handling remote requests to list 508files, and will not execute 509.Pa /bin/ls 510in either a chrooted or non-chrooted environment. The 511.Pa ~/bin/ls 512executable need not be placed into the chrooted tree, nor need the 513.Pa ~/bin 514directory exist. 515.Sh FILES 516.Bl -tag -width /etc/ftpwelcome -compact 517.It Pa /etc/ftpusers 518List of unwelcome/restricted users. 519.It Pa /etc/ftpchroot 520List of normal users who should be chroot'd. 521.It Pa /etc/ftphosts 522Virtual hosting configuration file. 523.It Pa /etc/ftpwelcome 524Welcome notice. 525.It Pa /etc/ftpmotd 526Welcome notice after login. 527.It Pa /var/run/nologin 528Displayed and access refused. 529.It Pa /var/log/ftpd 530Log file for anonymous transfers. 531.El 532.Sh SEE ALSO 533.Xr ftp 1 , 534.Xr key 1 , 535.Xr umask 2 , 536.Xr getusershell 3 , 537.Xr ftpchroot 5 , 538.Xr login.conf 5 , 539.Xr inetd 8 , 540.Xr syslogd 8 541.Sh BUGS 542The server must run as the super-user 543to create sockets with privileged port numbers. It maintains 544an effective user id of the logged in user, reverting to 545the super-user only when binding addresses to sockets. The 546possible security holes have been extensively 547scrutinized, but are possibly incomplete. 548.Sh HISTORY 549The 550.Nm 551command appeared in 552.Bx 4.2 . 553IPv6 support was added in WIDE Hydrangea IPv6 stack kit. 554