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

NAME
     tftpd - DARPA Internet Trivial File Transfer Protocol server

SYNOPSIS
     tftpd [-bcdln] [-g group] [-p pathsep] [-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'
     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.  Filenames beginning in
     "../" or containing "/../" are not allowed.  Unless -c is used, 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 /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.

     The options are:

     -b             Allow clients which return acknowledgements to the
                    broadcast address to communicate with the tftp server.
                    Some tftp clients, notably ones resident in the ROMs of
                    older Cisco equipment, return their acknowledgements to
                    the broadcast address rather than the server's unicast
                    address.

     -c             Allow unrestricted creation of new files.  Without this
                    flag, only existing publicly writable files can be
                    overwritten.

     -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.

     -l             Logs all requests using syslog(3).

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

     -p pathsep     All occurrences of the single character pathsep (path
                    separator) in the requested filename are replaced with
                    `/'.

     -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), inetd(8)

     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 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,
     tftpd accepts a sequence of block numbers which wrap to zero after 65535.

     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.

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 restrictions
     in place.  The exact methods are specific to each site and therefore
     difficult to document here.

     If unrestricted file upload is enabled via the -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.

NetBSD 10.99                      May 5, 2015                     NetBSD 10.99