atftpd - Trivial File Transfer Protocol Server.

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

                                                December 27, 2000                                      ATFTPD(8)

atftpd  is  a  TFTP (RFC1350) server. By default it is started by inetd on most systems, 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.

       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.

       atftpd - Trivial File Transfer Protocol Server.

       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-windowsize
              disable   'windowsize'  from  RFC7440.  This  will  prevent  the  server  from  acknowledging  the
              'windowsize' 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 run
              in daemon mode, /dev/stdout or /dev/stderr can be used.  Specifying a single dash as the  filename
              will send logs to stdout (file descriptor 1).

       --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 getservbyname(3).

       --bind-address<IPaddress>
              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 allows one 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 incoming 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.

       --prevent-sas
              Address  the Sorcerer's Apprentice Syndrome situation as requested by RFC 1350.  This RFC requires
              repeated responses to a single packet to be rejected. Thus a block will only get retransmitted  on
              a  timeout.   For  backward  compatibility,  the  default stays to ignore this RFC.  So blocks get
              transmitted on every request.

       --mcast-switch-client
              This option allows the server to proceed with the next multicast client as  soon  as  the  current
              client  timeout.  When the current master 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,
              proceeding 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.

       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.

       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.

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

       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.

atftpd [options] directory