TFTPD(8) BSD System Manager's Manual TFTPD(8)
NAME
tftpd -- DARPA Internet Trivial File Transfer Protocol server
SYNOPSIS
tftpd [-d] [-g group] [-i] [-l] [-n] [-s directory] [-u user] [directory ...]
DESCRIPTION
tftpd is a server which supports the DARPA Trivial File Transfer Protocol. The TFTP server operates at the port indicated in the 'tftp' ser-
vice description; see services(5). This server should not be started manually; instead, it should be run using launchd(8) using the plist
/System/Library/LaunchDaemons/tftp.plist. It may be started using the launchctl(1) load command; refer to the documentation for that utility
for more information.
The use of tftp(1) does not require an account or password on the remote system. Due to the lack of authentication information, tftpd will
allow only publicly readable files to be accessed. Filenames beginning in ``../'' or containing ``/../'' are not allowed. Files may be
written to only if they already exist and are publicly writable.
Note that this extends the concept of "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.
Access to files may be restricted by invoking tftpd with a list of directories by including up to 20 pathnames as server program arguments in
/System/Library/LaunchDaemons/tftp.plist. In this case access is restricted to files whose names are prefixed by the one of the given direc-
tories. The given directories are also treated as a search path for relative filename requests.
The options are:
-d Enable verbose debugging messages to syslogd(8).
-g group Change gid to that of group on startup. If this isn't specified, the gid is set to that of the user specified with -u.
-i Enable insecure mode, no realpath(3).
-l Logs all requests using syslog(3).
-n Suppresses negative acknowledgement of requests for nonexistent relative filenames.
-s directory
tftpd will chroot(2) to directory on startup. This is recommended for security reasons (so that files other than those in the
/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 'tftpboot' to '.' under /tftpboot.
-u user Change uid to that of user on startup. If -u isn't given, user defaults to ``nobody''. If -g isn't also given, change the gid to
that of user as well.
SEE ALSO
tftp(1), launchd(8), launchctl(1), launchd.plist(5)
The TFTP Protocol (Revision 2), RFC, 1350, July 1992.
TFTP Option Extension, RFC, 2347, May 1998.
TFTP Blocksize Option, RFC, 2348, May 1998.
TFTP Timeout Interval and Transfer Size Options, RFC, 2349, May 1998.
HISTORY
The tftpd command appeared in 4.2BSD.
The -s flag appeared in NetBSD 1.0.
The -g and -u flags appeared in NetBSD 1.4.
IPv6 support was implemented by WIDE/KAME project in 1999.
TFTP options were implemented by Wasabi Systems, Inc., in 2003, and first appeared in NetBSD 2.0 .
BUGS
Files larger than 33488896 octets (65535 blocks) cannot be transferred without client and server supporting blocksize negotiation (RFCs 2347
and 2348).
Many tftp clients will not transfer files over 16744448 octets (32767 blocks).
SECURITY CONSIDERATIONS
You are strongly advised to set up tftpd using the -s flag in conjunction with the name of the directory that contains the files that tftpd
will serve to remote hosts (e.g., /tftpboot). This ensures that only the files that should be served to remote hosts can be accessed by
them.
Because there is no user-login or validation within the TFTP protocol, the remote site will probably have some sort of file-access restric-
tions in place. The exact methods are specific to each site and therefore difficult to document here.
BSD
June 11, 2003 BSD