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 June 22, 2011 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, d Ar [value] 154Enables debug output. 155If 156.Ar value 157is not specified, then the debug level is increased by one 158for each instance of 159.Fl d 160which is specified. 161.Pp 162If 163.Ar value 164is specified, then the debug level is set to 165.Ar value . 166The debug level is a bitmask implemented in 167.Pa src/libexec/tftpd/tftp-utils.h . 168Valid values are 0 (DEBUG_NONE), 1 (DEBUG_PACKETS), 2, (DEBUG_SIMPLE), 1694 (DEBUG_OPTIONS), and 8 (DEBUG_ACCESS). Multiple debug values can be combined 170in the bitmask by logically OR'ing the values. For example, specifying 171.Fl d 172.Ar 15 173will enable all the debug values. 174.It Fl l 175Log all requests using 176.Xr syslog 3 177with the facility of 178.Dv LOG_FTP . 179.Sy Note : 180Logging of 181.Dv LOG_FTP 182messages 183must also be enabled in the syslog configuration file, 184.Xr syslog.conf 5 . 185.It Fl n 186Suppress negative acknowledgement of requests for nonexistent 187relative filenames. 188.It Fl o 189Disable support for RFC2347 style TFTP Options. 190.It Fl s Ar directory 191Cause 192.Nm 193to change its root directory to 194.Ar directory . 195After doing that but before accepting commands, 196.Nm 197will switch credentials to an unprivileged user. 198.It Fl u Ar user 199Switch credentials to 200.Ar user 201(default 202.Dq Li nobody ) 203when the 204.Fl s 205option is used. 206The user must be specified by name, not a numeric UID. 207.It Fl U Ar umask 208Set the 209.Ar umask 210for newly created files. 211The default is 022 212.Pq Dv S_IWGRP | S_IWOTH . 213.It Fl w 214Allow write requests to create new files. 215By default 216.Nm 217requires that the file specified in a write request exist. 218Note that this only works in directories writable by the user 219specified with 220.Fl u 221option 222.It Fl W 223As 224.Fl w 225but append a YYYYMMDD.nn sequence number to the end of the filename. 226Note that the string YYYYMMDD can be changed with the 227.Fl F 228option. 229.El 230.Sh SEE ALSO 231.Xr tftp 1 , 232.Xr chroot 2 , 233.Xr syslog 3 , 234.Xr inetd.conf 5 , 235.Xr services 5 , 236.Xr syslog.conf 5 , 237.Xr inetd 8 238.Pp 239The following RFC's are supported: 240.Rs 241.%T RFC 1350: The TFTP Protocol (Revision 2) 242.Re 243.Rs 244.%T RFC 2347: TFTP Option Extension 245.Re 246.Rs 247.%T RFC 2348: TFTP Blocksize Option 248.Re 249.Rs 250.%T RFC 2349: TFTP Timeout Interval and Transfer Size Options 251.Re 252.Pp 253The non-standard 254.Cm rollover 255and 256.Cm blksize2 257TFTP options are mentioned here: 258.Rs 259.%T Extending TFTP 260.%U http://www.compuphase.com/tftp.htm 261.Re 262.Sh HISTORY 263The 264.Nm 265utility appeared in 266.Bx 4.2 ; 267the 268.Fl s 269option was introduced in 270.Fx 2.2 , 271the 272.Fl u 273option was introduced in 274.Fx 4.2 , 275the 276.Fl c 277option was introduced in 278.Fx 4.3 , 279and the 280.Fl F 281and 282.Fl W 283options were introduced in 284.Fx 7.4 . 285.Pp 286Support for Timeout Interval and Transfer Size Options (RFC2349) 287was introduced in 288.Fx 5.0 , 289support for the TFTP Blocksize Option (RFC2348) and the blksize2 option 290was introduced in 291.Fx 7.4 . 292.Pp 293Edwin Groothuis <edwin@FreeBSD.org> performed a major rewrite of the 294.Nm 295and 296.Xr tftp 1 297code to support RFC2348. 298.Sh NOTES 299Files larger than 33,553,919 octets (65535 blocks, last one <512 300octets) cannot be correctly transferred without client and server 301supporting blocksize negotiation (RFCs 2347 and 2348), 302or the non-standard TFTP rollover option. 303As a kludge, 304.Nm 305accepts a sequence of block number which wrap to zero after 65535, 306even if the rollover option is not specified. 307.Pp 308Many tftp clients will not transfer files over 16,776,703 octets 309(32767 blocks), as they incorrectly count the block number using 310a signed rather than unsigned 16-bit integer. 311