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.\" $DragonFly: src/libexec/ftpd/ftpd.8,v 1.2 2003/06/17 04:27:07 dillon Exp $ 35.\" 36.Dd January 27, 2000 37.Dt FTPD 8 38.Os 39.Sh NAME 40.Nm ftpd 41.Nd Internet File Transfer Protocol server 42.Sh SYNOPSIS 43.Nm 44.Op Fl 46AdDEhmMoOrRSUvW 45.Op Fl l Op Fl l 46.Op Fl a Ar address 47.Op Fl p Ar file 48.Op Fl P Ar port 49.Op Fl t Ar timeout 50.Op Fl T Ar maxtimeout 51.Op Fl u Ar umask 52.Sh DESCRIPTION 53.Nm Ftpd 54is the 55Internet File Transfer Protocol 56server process. The server uses the 57.Tn TCP 58protocol 59and listens at the port specified with the 60.Fl P 61option or in the 62.Dq ftp 63service specification; see 64.Xr services 5 . 65.Pp 66Available options: 67.Bl -tag -width indent 68.It Fl 4 69When 70.Fl D 71is specified, accept IPv4 connections. 72When 73.Fl 6 74is also specified, accept IPv4 connection via 75.Dv AF_INET6 76socket. 77When 78.Fl 6 79is not specified, accept IPv4 connection via 80.Dv AF_INET 81socket. 82.It Fl 6 83When 84.Fl D 85is specified, accept connections via 86.Dv AF_INET6 87socket. 88.It Fl a 89When 90.Fl D 91is specified, accept connections only on the specified 92.Ar address . 93.It Fl A 94Allow only anonymous ftp access. 95.It Fl d 96Debugging information is written to the syslog using 97.Dv LOG_FTP . 98.It Fl D 99With this option set, 100.Nm 101will detach and become a daemon, accepting connections on the FTP port and 102forking children processes to handle them. 103This is lower overhead than starting 104.Nm 105from 106.Xr inetd 8 107and is thus useful on busy servers to reduce load. 108.It Fl E 109Disable the EPSV command. 110This is useful for servers behind older firewalls. 111.It Fl h 112Disable printing host-specific information, such as the 113server software version or hostname, in server messages. 114.It Fl l 115Each successful and failed 116.Xr ftp 1 117session is logged using syslog with a facility of 118.Dv LOG_FTP . 119If this option is specified twice, the retrieve (get), store (put), append, 120delete, make directory, remove directory and rename operations and 121their filename arguments are also logged. 122Note: 123.Dv LOG_FTP 124messages 125are not displayed by 126.Xr syslogd 8 127by default, and may have to be enabled in 128.Xr syslogd 8 Ns 's 129configuration file. 130.It Fl m 131Permit anonymous users to overwrite or modify 132existing files if allowed by filesystem permissions. 133By default, anonymous users cannot modify existing files; 134in particular, files to upload will be created under a unique name. 135.It Fl M 136Prevent anonymous users from creating directories. 137.It Fl o 138Put server in write-only mode. 139RETR is disabled, preventing downloads. 140.It Fl O 141Put server in write-only mode for anonymous users only. 142RETR is disabled for anonymous users, preventing anonymous downloads. 143This has no effect if 144.Fl o 145is also specified. 146.It Fl p 147When 148.Fl D 149is specified, write the daemon's process ID to 150.Ar file . 151.It Fl P 152When 153.Fl D 154is specified, accept connections at 155.Ar port , 156specified as a numeric value or service name, instead of at the default 157.Dq ftp 158port. 159.It Fl r 160Put server in read-only mode. 161All commands which may modify the local filesystem are disabled. 162.It Fl R 163With this option set, 164.Nm 165will revert to historical behavior with regard to security checks on 166user operations and restrictions on PORT requests. 167Currently, 168.Nm 169will only honor PORT commands directed to unprivileged ports on the 170remote user's host (which violates the FTP protocol specification but 171closes some security holes). 172.It Fl S 173With this option set, 174.Nm 175logs all anonymous file downloads to the file 176.Pa /var/log/ftpd 177when this file exists. 178.It Fl t 179The inactivity timeout period is set to 180.Ar timeout 181seconds (the default is 15 minutes). 182.It Fl T 183A client may also request a different timeout period; 184the maximum period allowed may be set to 185.Ar timeout 186seconds with the 187.Fl T 188option. 189The default limit is 2 hours. 190.It Fl u 191The default file creation mode mask is set to 192.Ar umask , 193which is expected to be an octal numeric value. 194Refer to 195.Xr umask 2 196for details. 197.It Fl U 198In previous versions of 199.Nm , 200when a passive mode client requested a data connection to the server, 201the server would use data ports in the range 1024..4999. Now, by default, 202the server will use data ports in the range 49152..65535. Specifying this 203option will revert to the old behavior. 204.It Fl v 205A synonym for 206.Fl d . 207.It Fl W 208Don't log FTP sessions to 209.Pa /var/log/wtmp . 210.El 211.Pp 212The file 213.Pa /var/run/nologin 214can be used to disable ftp access. 215If the file exists, 216.Nm 217displays it and exits. 218If the file 219.Pa /etc/ftpwelcome 220exists, 221.Nm 222prints it before issuing the 223.Dq ready 224message. 225If the file 226.Pa /etc/ftpmotd 227exists, 228.Nm 229prints it after a successful login. Note the motd file used is the one 230relative to the login environment. This means the one in 231.Pa ~ftp/etc 232in the anonymous user's case. 233.Pp 234The ftp server currently supports the following ftp requests. 235The case of the requests is ignored. Requests marked [RW] are 236disabled if 237.Fl r 238is specified. 239.Bl -column "Request" -offset indent 240.It Sy Request Ta Sy "Description" 241.It ABOR Ta "abort previous command" 242.It ACCT Ta "specify account (ignored)" 243.It ALLO Ta "allocate storage (vacuously)" 244.It APPE Ta "append to a file [RW]" 245.It CDUP Ta "change to parent of current working directory" 246.It CWD Ta "change working directory" 247.It DELE Ta "delete a file [RW]" 248.It EPRT Ta "specify data connection port, multiprotocol" 249.It EPSV Ta "prepare for server-to-server transfer, multiprotocol" 250.It HELP Ta "give help information" 251.It LIST Ta "give list files in a directory" Pq Dq Li "ls -lgA" 252.It LPRT Ta "specify data connection port, multiprotocol" 253.It LPSV Ta "prepare for server-to-server transfer, multiprotocol" 254.It MDTM Ta "show last modification time of file" 255.It MKD Ta "make a directory [RW]" 256.It MODE Ta "specify data transfer" Em mode 257.It NLST Ta "give name list of files in directory" 258.It NOOP Ta "do nothing" 259.It PASS Ta "specify password" 260.It PASV Ta "prepare for server-to-server transfer" 261.It PORT Ta "specify data connection port" 262.It PWD Ta "print the current working directory" 263.It QUIT Ta "terminate session" 264.It REST Ta "restart incomplete transfer" 265.It RETR Ta "retrieve a file" 266.It RMD Ta "remove a directory [RW]" 267.It RNFR Ta "specify rename-from file name [RW]" 268.It RNTO Ta "specify rename-to file name [RW]" 269.It SITE Ta "non-standard commands (see next section)" 270.It SIZE Ta "return size of file" 271.It STAT Ta "return status of server" 272.It STOR Ta "store a file [RW]" 273.It STOU Ta "store a file with a unique name [RW]" 274.It STRU Ta "specify data transfer" Em structure 275.It SYST Ta "show operating system type of server system" 276.It TYPE Ta "specify data transfer" Em type 277.It USER Ta "specify user name" 278.It XCUP Ta "change to parent of current working directory (deprecated)" 279.It XCWD Ta "change working directory (deprecated)" 280.It XMKD Ta "make a directory (deprecated) [RW]" 281.It XPWD Ta "print the current working directory (deprecated)" 282.It XRMD Ta "remove a directory (deprecated) [RW]" 283.El 284.Pp 285The following non-standard or 286.Tn UNIX 287specific commands are supported 288by the 289SITE request. 290.Pp 291.Bl -column Request -offset indent 292.It Sy Request Ta Sy Description 293.It UMASK Ta change umask, e.g. ``SITE UMASK 002'' 294.It IDLE Ta set idle-timer, e.g. ``SITE IDLE 60'' 295.It CHMOD Ta "change mode of a file [RW], e.g. ``SITE CHMOD 755 filename''" 296.It MD5 Ta "report the files MD5 checksum, e.g. ``SITE MD5 filename''" 297.It HELP Ta give help information 298.El 299.Pp 300Note: SITE requests are disabled in case of anonymous logins. 301.Pp 302The remaining ftp requests specified in Internet RFC 959 303are 304recognized, but not implemented. 305MDTM and SIZE are not specified in RFC 959, but will appear in the 306next updated FTP RFC. 307To avoid possible denial-of-service attacks, SIZE requests against 308files larger than 10240 bytes will be denied if the current transfer 309type is ASCII. 310.Pp 311The ftp server will abort an active file transfer only when the 312ABOR 313command is preceded by a Telnet "Interrupt Process" (IP) 314signal and a Telnet "Synch" signal in the command Telnet stream, 315as described in Internet RFC 959. 316If a 317STAT 318command is received during a data transfer, preceded by a Telnet IP 319and Synch, transfer status will be returned. 320.Pp 321.Nm Ftpd 322interprets file names according to the 323.Dq globbing 324conventions used by 325.Xr csh 1 . 326This allows users to utilize the metacharacters 327.Dq Li \&*?[]{}~ . 328.Pp 329.Nm Ftpd 330authenticates users according to six rules. 331.Pp 332.Bl -enum -offset indent 333.It 334The login name must be in the password data base 335and not have a null password. 336In this case a password must be provided by the client before any 337file operations may be performed. 338If the user has an S/Key key, the response from a successful USER 339command will include an S/Key challenge. 340The client may choose to respond with a PASS command giving either 341a standard password or an S/Key one-time password. 342The server will automatically determine which type of 343password it has been given and attempt to authenticate accordingly. 344See 345.Xr key 1 346for more information on S/Key authentication. 347S/Key is a Trademark of Bellcore. 348.It 349The login name must not appear in the file 350.Pa /etc/ftpusers . 351.It 352The login name must not be a member of a group specified in the file 353.Pa /etc/ftpusers . 354Entries in this file interpreted as group names are prefixed by an "at" 355.Ql \&@ 356sign. 357.It 358The user must have a standard shell returned by 359.Xr getusershell 3 . 360.It 361If the user name appears in the file 362.Pa /etc/ftpchroot , 363or the user is a member of a group with a group entry in this file, 364i.e. one prefixed with 365.Ql \&@ , 366the session's root will be changed to the directory specified 367in this file or to the user's login directory by 368.Xr chroot 2 369as for an 370.Dq anonymous 371or 372.Dq ftp 373account (see next item). 374See 375.Xr ftpchroot 5 376for a detailed description of the format of this file. 377This facility may also be triggered by enabling the boolean "ftp-chroot" 378capability in 379.Xr login.conf 5 . 380However, the user must still supply a password. 381This feature is intended as a compromise between a fully anonymous 382account and a fully privileged account. 383The account should also be set up as for an anonymous account. 384.It 385If the user name is 386.Dq anonymous 387or 388.Dq ftp , 389an 390anonymous ftp account must be present in the password 391file (user 392.Dq ftp ) . 393In this case the user is allowed 394to log in by specifying any password (by convention an email address for 395the user should be used as the password). 396When the 397.Fl S 398option is set, all transfers are logged as well. 399.El 400.Pp 401In the last case, 402.Nm 403takes special measures to restrict the client's access privileges. 404The server performs a 405.Xr chroot 2 406to the home directory of the 407.Dq ftp 408user. 409As a special case if the 410.Dq ftp 411user's home directory pathname contains the 412.Dq \&/./ 413separator, 414.Nm 415uses its left-hand side as the name of the directory to do 416.Xr chroot 2 417to, and its right-hand side to change the current directory to afterwards. 418A typical example for this case would be 419.Pa /usr/local/ftp/./pub . 420In order that system security is not breached, it is recommended 421that the 422.Dq ftp 423subtree be constructed with care, following these rules: 424.Bl -tag -width "~ftp/pub" -offset indent 425.It Pa ~ftp 426Make the home directory owned by 427.Dq root 428and unwritable by anyone. 429.It Pa ~ftp/etc 430Make this directory owned by 431.Dq root 432and unwritable by anyone (mode 555). 433The files pwd.db (see 434.Xr passwd 5 ) 435and 436.Xr group 5 437must be present for the 438.Xr ls 439command to be able to produce owner names rather than numbers. 440The password field in 441.Xr passwd 442is not used, and should not contain real passwords. 443The file 444.Pa ftpmotd , 445if present, will be printed after a successful login. 446These files should be mode 444. 447.It Pa ~ftp/pub 448This directory and the subdirectories beneath it should be owned 449by the users and groups responsible for placing files in them, 450and be writable only by them (mode 755 or 775). 451They should 452.Em not 453be owned or writable by 454.Dq ftp 455or its group, otherwise guest users 456can fill the drive with unwanted files. 457.El 458.Pp 459If the system has multiple IP addresses, 460.Nm 461supports the idea of virtual hosts, which provides the ability to 462define multiple anonymous ftp areas, each one allocated to a different 463internet address. 464The file 465.Pa /etc/ftphosts 466contains information pertaining to each of the virtual hosts. 467Each host is defined on its own line which contains a number of 468fields separated by whitespace: 469.Bl -tag -offset indent -width hostname 470.It hostname 471Contains the hostname or IP address of the virtual host. 472.It user 473Contains a user record in the system password file. 474As with normal anonymous ftp, this user's access uid, gid and group 475memberships determine file access to the anonymous ftp area. 476The anonymous ftp area (to which any user is chrooted on login) 477is determined by the home directory defined for the account. 478User id and group for any ftp account may be the same as for the 479standard ftp user. 480.It statfile 481File to which all file transfers are logged, which 482defaults to 483.Pa /var/log/ftpd . 484.It welcome 485This file is the welcome message displayed before the server ready 486prompt. 487It defaults to 488.Pa /etc/ftpwelcome . 489.It motd 490This file is displayed after the user logs in. 491It defaults to 492.Pa /etc/ftpmotd . 493.El 494.Pp 495Lines beginning with a '#' are ignored and can be used to include 496comments. 497.Pp 498Defining a virtual host for the primary IP address or hostname 499changes the default for ftp logins to that address. 500The 'user', 'statfile', 'welcome' and 'motd' fields may be left 501blank, or a single hyphen '-' used to indicate that the default 502value is to be used. 503.Pp 504As with any anonymous login configuration, due care must be given 505to setup and maintenance to guard against security related problems. 506.Pp 507.Nm 508has internal support for handling remote requests to list 509files, and will not execute 510.Pa /bin/ls 511in either a chrooted or non-chrooted environment. The 512.Pa ~/bin/ls 513executable need not be placed into the chrooted tree, nor need the 514.Pa ~/bin 515directory exist. 516.Sh FILES 517.Bl -tag -width /etc/ftpwelcome -compact 518.It Pa /etc/ftpusers 519List of unwelcome/restricted users. 520.It Pa /etc/ftpchroot 521List of normal users who should be chroot'd. 522.It Pa /etc/ftphosts 523Virtual hosting configuration file. 524.It Pa /etc/ftpwelcome 525Welcome notice. 526.It Pa /etc/ftpmotd 527Welcome notice after login. 528.It Pa /var/run/nologin 529Displayed and access refused. 530.It Pa /var/log/ftpd 531Log file for anonymous transfers. 532.El 533.Sh SEE ALSO 534.Xr ftp 1 , 535.Xr key 1 , 536.Xr umask 2 , 537.Xr getusershell 3 , 538.Xr ftpchroot 5 , 539.Xr login.conf 5 , 540.Xr inetd 8 , 541.Xr syslogd 8 542.Sh BUGS 543The server must run as the super-user 544to create sockets with privileged port numbers. It maintains 545an effective user id of the logged in user, reverting to 546the super-user only when binding addresses to sockets. The 547possible security holes have been extensively 548scrutinized, but are possibly incomplete. 549.Sh HISTORY 550The 551.Nm 552command appeared in 553.Bx 4.2 . 554IPv6 support was added in WIDE Hydrangea IPv6 stack kit. 555