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

NAME

       atftpd - Trivial File Transfer Protocol Server.

SYNOPSIS

       atftpd [options] directory

DESCRIPTION

       atftpd  is  a  TFTP (RFC1350) server. By default it is started by inetd on most sytems, but may run as a stand alone daemon. This server is
       multi-threaded and supports all options described in RFC2347 (option extension), RFC2348 (blksize), RFC2349 (tsize and timeout) and RFC2090
       (multicast option). It also supports mtftp as defined in the PXE specification.

OPTIONS

       This  program supports both the usual GNU command line syntax, with long options starting with two dashes ('-') as well as short options. A
       description of the options is included below.

       -t, --tftpd-timeout <value>
	      Number of seconds of inactivity before the server exits. This value has meaning only when the server is started by inetd. In  daemon
	      mode, the server never exits. Default is 300 seconds.

       -r, --retry-timeout <value>
	      How many seconds to wait for a reply before retransmitting a packet. Default is 5 seconds. This can be overridden by the TFTP client
	      with the 'timeout' option.

       -m, --maxthread <value>
	      Maximum number of concurrent threads allowed. Default is 100.

       -v, --verbose[=value]
	      Increase or set the logging level. No arguments will increase by one the current value. Default is LOG_NOTICE, see syslog(3) for log
	      level. Valid value range from 0 (LOG_EMERG) to 7 (LOG_DEBUG).

       --trace
	      When verbose level is set to 7, this will output debug information for each packet sent or received from the network.

       --no-timeout
	      disable 'timeout' from RFC2349. This will prevent the server from acknowledging the 'timeout' option requested by the client.

       --no-tsize
	      disable 'tsize' from RFC2349. This will prevent the server from acknowledging the 'tsize' option requested by the client.

       --no-blksize
	      disable 'blksize' from RFC2348. This will prevent the server from acknowledging the 'blksize' request by the client.

       --no-multicast
	      disable 'multicast' from RFC2090. This will prevent the server from acknowledging the 'multicast' request by the client.

       --logfile <logfile>
	      Log  to  a  specific  file  instead of only syslog. 'nobody' (or any user used to run the server) must have permissions on the given
	      file.  Assuming  the  file  is  /var/log/atftpd.log,  simply  run:  "touch  /var/log/atftpd.log"	and  then  "chown   nobody.nogroup
	      /var/log/atftpd.log". When the server is ran in daemon mode, /dev/stdout or /dev/stderr can be used.

       --pidfile
	      Write  the PID of the server to the specified file. This may be useful when automatically starting and stopping one or more instance
	      of the server.

       --daemon
	      Run as a daemon. Do not use this option if atftpd is started by inetd.

       --no-fork
	      When --daemon is specified, this option will prevent the server from forking to background. It is useful for  debugging  purpose	or
	      specialized usage.

       --user <user[.group]>
	      By default, the server change identity to the user nobody and group nogroup. Specify an alternate user.group with this option.

       --group <group>
	      Alternate way of specifying the group. If group is specified with --user and --group, the last option will be used.

       --port <number>
	      Specify  the  port  on  which atftpd listens. Useful when --daemon is specified. Default is standard tftp port as determined by get-
	      servbyname(3).

       --bind-address <IP address>
	      Specify the IP address which atftpd binds to. Useful when --daemon is specified. Default is to bind  to  all  interfaces.  Only  one
	      address can be specified, the server can only listen to one or all interfaces.

       --mcast-ttl
	      Specify the TTL to be used for multicast datagram. By default a value of 1 is used. Note that TTL has a special meaning in multicast
	      as it is used to determine the scope of the packets. The value of 1 means the packets don't leave  the  local  network,  see  ip(4).
	      Scope may also be determine by the address as described RFC2365.

       --mcast-addr
	      Specify  the  IP	address  range	to  be	used  for  multicast  transfer.  Format  string  may  comprise	range  and list of values:
	      "239.255.0.0-31,128-132,200".  Default value is "239.255.0.0-255". This address range is proposed in RFC2365 for local scope.

       --mcast-port
	      Specify the UDP port to use for multicast transfer. Format string may contain range and list of port number:  "1758-2000,8000-9000".
	      default value is "1758".

       --pcre <file>
	      Specify  a  pattern/replacement  file to use. This allow to replace requested file name based on Perl Compatible Regular Expression.
	      See README.PCRE.

       --pcre-test <file>
	      Test a pattern/replacement file. When using this option, the server will not start as usual but just read file name from	stdin  and
	      printout the substitution.

       --mtftp <file>
	      This  will  start  a mtftp server thread for each valid entry in the supplied file. See PXE specification for detail about mtftp. An
	      example file is provided in the source distribution.

       --mtftp-port <port>
	      Port the mtftp server shall listen to for incomming request.

       --no-source-port-checking
	      In some specific cases of networks using load balancer or other equipment performing NAT (network address translation),  some  needs
	      to  disable source port checking because port number as been translated. If you want to use this feature, you must know why you need
	      it and the implication. Be aware that this option violate the RFC1350. This option has effect only for non-multicast transfer.

       --mcast-switch-client
	      This option allow the server to proceed with the next multicast client as soon as the current client timeout. When the current  mas-
	      ter  client fails to send an acknowledge (ACK) to the server, the server will send an option acknowledge (OACK) to the master client
	      with the field MC (master client) set to false and send an OACK to the next multicast client with  MC  set  to  true.  Without  this
	      option, the server will retry the current master client up to 5 times and then mark it done, proceding with the next one.

       -V, --version
	      Show version of program.

       -h, --help
	      Show summary of options.

       path   This  is	the  root  directory used by the TFTP server. All requested files from a TFTP client must reside in this directory. If not
	      specified, the directory defaults to /tftpboot. Since atftpd run as the nobody user, the permission of the  directory  must  be  set
	      properly to allow file reading and writing.

STATS

       Starting  with  release	0.2,  the server collects some statistics.  Currently the server compute system load, time between connections and
       some thread statistics like number of file sent, received, number of abort... To see those stats in the logs, you need to  set  --verbose=6
       (LOG_NOTICE) or higher.

SECURITY

       TFTP by itself has no provision for security. There is no user authentication and TFTP clients get access to all files within the specified
       root directory for which the server has permission.

       Some level of security can be gained using atftp libwrap support. Adding proper entry to /etc/hosts.allow and /etc/hosts.deny will restrict
       access to trusted hosts. Daemon name to use in these files is in.tftpd.

PCRE

       The atftpd server provides a way to dynamically replace requested file name by a new one based on Perl compatible regular expression. Pairs
       of pattern/replacement are read from the specified files. Upon reception of a read request, the server will first try to open the file name
       requested.  If it fails, then it will search for a replacement based on the content of the pattern file. If this still fails, then an error
       will be sent to the client. This feature is available only for read request. It makes no sense doing this substitution for  client  writing
       files to the server.

MTFTP

       The  mtftp name refer to multicasrt tftp as define by the PXE specification. See pxespec.txt for the source of the specification. Note that
       this is not the same as RFC2090. PXE compliant boot implements mtftp, not RFC2090.

SEE ALSO

       inetd(8),hosts_access(5),libpcre(7), RFC1350, RFC2090, RFC2347, RFC2348, RFC2349 and pxespec.pdf.

AUTHOR

       This manual page was written by Remi Lefebvre <remi@debian.org> and Jean-Pierre Lefebvre <helix@step.polymtl.ca>.

								 December 27, 2000							 ATFTPD(8)