|Return to tftpd.8 CVS log||Up to [cvs.NetBSD.org] / src / libexec / tftpd|
|File: [cvs.NetBSD.org] / src / libexec / tftpd / tftpd.8 (download)
Revision 1.28, Thu Apr 29 21:34:04 2010 UTC (11 years, 7 months ago) by wiz
.\" $NetBSD: tftpd.8,v 1.28 2010/04/29 21:34:04 wiz Exp $ .\" .\" Copyright (c) 1983, 1991, 1993 .\" The Regents of the University of California. All rights reserved. .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice, this list of conditions and the following disclaimer in the .\" documentation and/or other materials provided with the distribution. .\" 3. Neither the name of the University nor the names of its contributors .\" may be used to endorse or promote products derived from this software .\" without specific prior written permission. .\" .\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE .\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF .\" SUCH DAMAGE. .\" .\" from: @(#)tftpd.8 8.1 (Berkeley) 6/4/93 .\" .Dd April 22, 2010 .Dt TFTPD 8 .Os .Sh NAME .Nm tftpd .Nd .Tn DARPA Internet Trivial File Transfer Protocol server .Sh SYNOPSIS .Nm .Op Fl cdln .Op Fl g Ar group .Op Fl p Ar pathsep .Op Fl s Ar directory .Op Fl u Ar user .Op Ar directory ... .Sh DESCRIPTION .Nm is a server which supports the .Tn DARPA Trivial File Transfer Protocol. The .Tn TFTP server operates at the port indicated in the .Ql tftp service description; see .Xr services 5 . The server is normally started by .Xr inetd 8 . .Pp The use of .Xr tftp 1 does not require an account or password on the remote system. Due to the lack of authentication information, .Nm will allow only publicly readable files to be accessed. Filenames beginning in .Dq Pa ../ or containing .Dq Pa /../ are not allowed. Unless .Fl c is used, files may be written to only if they already exist and are publicly writable. .Pp Note that this extends the concept of .Qq public to include all users on all hosts that can be reached through the network; this may not be appropriate on all systems, and its implications should be considered before enabling tftp service. The server should have the user ID with the lowest possible privilege. .Pp Access to files may be restricted by invoking .Nm with a list of directories by including up to 20 pathnames as server program arguments in .Pa /etc/inetd.conf . In this case access is restricted to files whose names are prefixed by the one of the given directories. The given directories are also treated as a search path for relative filename requests. .Pp The options are: .Bl -tag -width "XsXdirectoryX" .It Fl c Allow unrestricted creation of new files. Without this flag, only existing publicly writable files can be overwritten. .It Fl d Enable verbose debugging messages to .Xr syslogd 8 . .It Fl g Ar group Change gid to that of .Ar group on startup. If this isn't specified, the gid is set to that of the .Ar user specified with .Fl u . .It Fl l Logs all requests using .Xr syslog 3 . .It Fl n Suppresses negative acknowledgement of requests for nonexistent relative filenames. .It Fl p Ar pathsep All occurances of the single character .Ar pathsep (path separator) in the requested filename are replaced with .Sq / . .It Fl s Ar directory .Nm will .Xr chroot 2 to .Ar directory on startup. This is recommended for security reasons (so that files other than those in the .Pa /tftpboot directory aren't accessible). If the remote host passes the directory name as part of the file name to transfer, you may have to create a symbolic link from .Sq tftpboot to .Sq \&. under .Pa /tftpboot . .It Fl u Ar user Change uid to that of .Ar user on startup. If .Fl u isn't given, .Ar user defaults to .Dq nobody . If .Fl g isn't also given, change the gid to that of .Ar user as well. .El .Sh SEE ALSO .Xr tftp 1 , .Xr inetd 8 .Rs .%R RFC .%N 1350 .%D July 1992 .%T "The TFTP Protocol (Revision 2)" .Re .Rs .%R RFC .%N 2347 .%D May 1998 .%T "TFTP Option Extension" .Re .Rs .%R RFC .%N 2348 .%D May 1998 .%T "TFTP Blocksize Option" .Re .Rs .%R RFC .%N 2349 .%D May 1998 .%T "TFTP Timeout Interval and Transfer Size Options" .Re .Sh HISTORY The .Nm command appeared in .Bx 4.2 . .Pp The .Fl s flag appeared in .Nx 1.0 . .Pp The .Fl g and .Fl u flags appeared in .Nx 1.4 . .Pp IPv6 support was implemented by WIDE/KAME project in 1999. .Pp TFTP options were implemented by Wasabi Systems, Inc., in 2003, and first appeared in .Nx 2.0 . .Sh BUGS Files larger than 33,553,919 octets (65535 blocks, last one less than 512 octets) cannot be correctly transferred without client and server supporting blocksize negotiation (RFCs 2347 and 2348). As a kludge, .Nm accepts a sequence of block numbers which wrap to zero after 65535. .Pp Many tftp clients will not transfer files over 16,776,703 octets (32767 blocks), as they incorrectly count the block number using a signed rather than unsigned 16-bit integer. .Sh SECURITY CONSIDERATIONS You are .Em strongly advised to set up .Nm using the .Fl s flag in conjunction with the name of the directory that contains the files that .Nm will serve to remote hosts (e.g., .Pa /tftpboot ) . This ensures that only the files that should be served to remote hosts can be accessed by them. .Pp Because there is no user-login or validation within the .Tn TFTP protocol, the remote site will probably have some sort of file-access restrictions in place. The exact methods are specific to each site and therefore difficult to document here. .Pp If unrestricted file upload is enabled via the .Fl c option, care should be taken that this can be used to fill up disk space in an uncontrolled manner if this is used in an insecure environment.