1.\" Copyright (c) 1983, 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.\" @(#)tftpd.8 8.1 (Berkeley) 6/4/93 33.\" $FreeBSD$ 34.\" 35.Dd September 14, 2000 36.Dt TFTPD 8 37.Os 38.Sh NAME 39.Nm tftpd 40.Nd Internet Trivial File Transfer Protocol server 41.Sh SYNOPSIS 42.Nm tftpd 43.Op Fl cdClnow 44.Op Fl F Ar strftime-format 45.Op Fl s Ar directory 46.Op Fl u Ar user 47.Op Fl U Ar umask 48.Op Ar directory ... 49.Sh DESCRIPTION 50The 51.Nm 52utility is a server which supports the 53Internet Trivial File Transfer 54Protocol 55.Pq Tn RFC 1350 . 56The 57.Tn TFTP 58server operates 59at the port indicated in the 60.Ql tftp 61service description; 62see 63.Xr services 5 . 64The server is normally started by 65.Xr inetd 8 . 66.Pp 67The use of 68.Xr tftp 1 69does not require an account or password on the remote system. 70Due to the lack of authentication information, 71.Nm 72will allow only publicly readable files to be 73accessed. 74Files containing the string 75.Dq Li "/../" 76or starting with 77.Dq Li "../" 78are not allowed. 79Files may be written only if they already exist and are publicly writable. 80Note that this extends the concept of 81.Dq public 82to include 83all users on all hosts that can be reached through the network; 84this may not be appropriate on all systems, and its implications 85should be considered before enabling tftp service. 86The server should have the user ID with the lowest possible privilege. 87.Pp 88Access to files may be restricted by invoking 89.Nm 90with a list of directories by including up to 20 pathnames 91as server program arguments in 92.Xr inetd.conf 5 . 93In this case access is restricted to files whose 94names are prefixed by the one of the given directories. 95The given directories are also treated as a search path for 96relative filename requests. 97.Pp 98The 99.Fl s 100option provides additional security by changing 101the root directory of 102.Nm , 103thereby prohibiting accesses to outside of the specified 104.Ar directory . 105Because 106.Xr chroot 2 107requires super-user privileges, 108.Nm 109must be run as 110.Li root . 111However, after performing the 112.Xr chroot 2 113call, 114.Nm 115will set its user ID to that of the specified 116.Ar user , 117or 118.Dq Li nobody 119if no 120.Fl u 121option is specified. 122.Pp 123The options are: 124.Bl -tag -width Ds 125.It Fl c 126Changes the default root directory of a connecting host via 127.Xr chroot 2 128based on the connecting IP address. 129This prevents multiple clients from writing to the same file at the same time. 130If the directory does not exist, the client connection is refused. 131The 132.Fl s 133option is required for 134.Fl c 135and the specified 136.Ar directory 137is used as a base. 138.It Fl C 139Operates the same as 140.Fl c 141except it falls back to 142.Ar directory 143specified via 144.Fl s 145if a directory does not exist for the client's IP. 146.It Fl F 147Use this 148.Xr strftime 3 149compatible format string for the creation of the suffix if 150.Fl W 151is specified. 152By default the string "%Y%m%d" is used. 153.It Fl d 154Enables debug output. 155If specified twice, it will log DATA and ACK packets too. 156.It Fl l 157Log all requests using 158.Xr syslog 3 159with the facility of 160.Dv LOG_FTP . 161.Sy Note : 162Logging of 163.Dv LOG_FTP 164messages 165must also be enabled in the syslog configuration file, 166.Xr syslog.conf 5 . 167.It Fl n 168Suppress negative acknowledgement of requests for nonexistent 169relative filenames. 170.It Fl o 171Disable support for RFC2347 style TFTP Options. 172.It Fl s Ar directory 173Cause 174.Nm 175to change its root directory to 176.Ar directory . 177After doing that but before accepting commands, 178.Nm 179will switch credentials to an unprivileged user. 180.It Fl u Ar user 181Switch credentials to 182.Ar user 183(default 184.Dq Li nobody ) 185when the 186.Fl s 187option is used. 188The user must be specified by name, not a numeric UID. 189.It Fl U Ar umask 190Set the 191.Ar umask 192for newly created files. 193The default is 022 194.Pq Dv S_IWGRP | S_IWOTH . 195.It Fl w 196Allow write requests to create new files. 197By default 198.Nm 199requires that the file specified in a write request exist. 200Note that this only works in directories writable by the user 201specified with 202.Fl u 203option 204.It Fl W 205As 206.Fl w 207but append a YYYYMMDD.nn sequence number to the end of the filename. 208Note that the string YYYYMMDD can be changed with the 209.Fl F 210option. 211.El 212.Sh SEE ALSO 213.Xr tftp 1 , 214.Xr chroot 2 , 215.Xr syslog 3 , 216.Xr inetd.conf 5 , 217.Xr services 5 , 218.Xr syslog.conf 5 , 219.Xr inetd 8 220.Rs 221.%A K. R. Sollins 222.%T The TFTP Protocol (Revision 2) 223.%D July 1992 224.%O RFC 1350, STD 33 225.Re 226.Sh HISTORY 227The 228.Nm 229utility appeared in 230.Bx 4.2 ; 231the 232.Fl s 233option was introduced in 234.Fx 2.2 , 235the 236.Fl u 237option was introduced in 238.Fx 4.2 , 239the 240.Fl c 241option was introduced in 242.Fx 4.3 , 243and the 244.Fl F 245and 246.Fl W 247options were introduced in 248.Fx 7.4 . 249.Pp 250Support for Timeout Interval and Transfer Size Options (RFC2349) 251was introduced in 252.Fx 5.0 , 253support for the TFTP Blocksize Option (RFC2348) and the blksize2 option 254was introduced in 255.Fx 7.4 . 256.Sh BUGS 257Files larger than 33488896 octets (65535 blocks) cannot be transferred 258without client and server supporting blocksize negotiation (RFC2348). 259.Pp 260Many tftp clients will not transfer files over 16744448 octets (32767 blocks). 261