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TFTPD(8) FreeBSD System Manager's Manual TFTPD(8) NAME tftpd -- Internet Trivial File Transfer Protocol server SYNOPSIS tftpd [-cdClnow] [-F strftime-format] [-s directory] [-u user] [-U umask] [directory ...] DESCRIPTION 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 option 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. -F Use this strftime(3) compatible format string for the creation of the suffix if -W is specified. By default the string "%Y%m%d" is used. -d Enables debug output. If specified twice, it will log DATA and ACK packets too. -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. -o Disable support for RFC2347 style TFTP Options. -s directory Cause tftpd to change its root directory to directory. After doing that but before accepting commands, tftpd will switch cre- dentials 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 write requests to create new files. By default tftpd requires that the file specified in a write request exist. Note that this only works in directories writable by the user speci- fied with -u option -W As -w but append a YYYYMMDD.nn sequence number to the end of the filename. Note that the string YYYYMMDD can be changed with the -F option. SEE ALSO 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 33. HISTORY 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, the -c option was introduced in FreeBSD 4.3, and the -F and -W options were introduced in FreeBSD 7.4. Support for Timeout Interval and Transfer Size Options (RFC2349) was introduced in FreeBSD 5.0, support for the TFTP Blocksize Option (RFC2348) and the blksize2 option was introduced in FreeBSD 7.4. BUGS Files larger than 33488896 octets (65535 blocks) cannot be transferred without client and server supporting blocksize negotiation (RFC2348). Many tftp clients will not transfer files over 16744448 octets (32767 blocks). FreeBSD 11.1 September 14, 2000 FreeBSD 11.1
NAME | SYNOPSIS | DESCRIPTION | SEE ALSO | HISTORY | BUGS
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