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TFTPD(8)		  BSD System Manager's Manual		      TFTPD(8)

     tftpd -- Internet Trivial File Transfer Protocol server

     tftpd [-cClnw] [-s	directory] [-u user] [-U umask]	[directory ...]

     The tftpd utility is a server which supports the Internet Trivial File
     Transfer Protocol (RFC 1350).  The	TFTP server operates at	the port indi-
     cated in the `tftp' service description; see services(5).	The server is
     normally started by inetd(8).

     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.  Files containing the	string
     "/../" or starting	with "../" are not allowed.  Files may be written 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	direc-
     tories by including up to 20 pathnames as server program arguments	in
     inetd.conf(5).  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.

     The -s option provides additional security	by changing the	root directory
     of	tftpd, thereby prohibiting accesses to outside of the specified
     directory.	 Because chroot(2) requires super-user privileges, tftpd must
     be	run as root.  However, after performing	the chroot(2) call, tftpd will
     set its user ID to	that of	the specified user, or "nobody"	if no -u op-
     tion is specified.

     The options are:

     -c	     Changes the default root directory	of a connecting	host via
	     chroot(2) based on	the connecting IP address.  This prevents mul-
	     tiple clients from	writing	to the same file at the	same time.  If
	     the directory does	not exist, the client connection is refused.
	     The -s option is required for -c and the specified	directory is
	     used as a base.

     -C	     Operates the same as -c except it falls back to directory speci-
	     fied via -s if a directory	does not exist for the client's	IP.

     -l	     Log all requests using syslog(3) with the facility	of LOG_FTP.
	     Note: Logging of LOG_FTP messages must also be enabled in the
	     syslog configuration file,	syslog.conf(5).

     -n	     Suppress negative acknowledgement of requests for nonexistent
	     relative filenames.

     -s	directory
	     Cause tftpd to change its root directory to directory.  After do-
	     ing that but before accepting commands, tftpd will	switch creden-
	     tials to an unprivileged user.

     -u	user
	     Switch credentials	to user	(default "nobody") when	the -s option
	     is	used.  The user	must be	specified by name, not a numeric UID.

     -U	umask
	     Set the umask for newly created files.  The default is 022
	     (S_IWGRP |	S_IWOTH).

     -w	     Allow writes requests to create new files.	 By default tftpd re-
	     quires that the file specified in a write request exist.

     tftp(1), chroot(2), syslog(3), inetd.conf(5), services(5),
     syslog.conf(5), inetd(8)

     K.	R. Sollins, The	TFTP Protocol (Revision	2), July 1992, RFC 1350, STD

     The tftpd utility appeared	in 4.2BSD; the -s option was introduced	in
     FreeBSD 2.2, the -u option	was introduced in FreeBSD 4.2, and the -c op-
     tion was introduced in FreeBSD 4.3.

     Files larger than 33488896	octets (65535 blocks) cannot be	transferred
     without client and	server supporting blocksize negotiation	(RFC1783).

     Many tftp clients will not	transfer files over 16744448 octets (32767

BSD			      September	14, 2000			   BSD


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