Provided by: tftpd_0.17-23ubuntu1_amd64 bug


     tftpd — DARPA Trivial File Transfer Protocol server


     tftpd [-n] [-s] [directory ...]


     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.  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 controlled by invoking tftpd with a list of directories by including
     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. If no directories are
     supplied the default is /tftpboot.  To give out access to the whole filesystem, should this
     be desired for some reason, supply / as an argument.

     Unfortunately, on multi-homed systems, it is impossible for tftpd to determine the address
     on which a packet was received. As a result, tftpd uses two different mechanisms to guess
     the best source address to use for replies. If the socket that inetd(8) passed to tftpd is
     bound to a particular address, tftpd uses that address for replies. Otherwise, tftpd uses
     ``UDP connect'' to let the kernel choose the reply address based on the destination of the
     replies and the routing tables. This means that most setups will work transparently, while
     in cases where the reply address must be fixed, the virtual hosting feature of inetd(8) can
     be used to ensure that replies go out from the correct address.  These considerations are
     important, because most tftp clients will reject reply packets that appear to come from an
     unexpected address.

     The options are:

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

     -s      All absolute filenames are treated as if they were preceded by the first directory
             argument, or /tftpboot if there is none.


     tftp(1), inetd(8)


     The tftpd command appeared in 4.2BSD.