tcpserver(1)                                         tcpserver(1)


NAME
       tcpserver - accepts incoming TCP connections.

SYNOPSIS
       tcpserver [ opts ] host port prog

DESCRIPTION
       opts  is  a  series  of getopt-style options.  host is one
       argument.  port is one argument.  prog consists of one  or
       more arguments.

       tcpserver waits for connections from TCP clients. For each
       connection, it runs prog, with descriptor 0  reading  from
       the  network  and  descriptor 1 writing to the network. It
       also sets up several environment variables.

       The server's address is given by host and port.  port  may
       be  a  name  from  /etc/services  or a number; if it is 0,
       tcpserver will choose a free TCP port.   host  may  be  0,
       allowing connections to any local IP address; or a dotted-
       decimal IP address,  allowing  connections  only  to  that
       address; or a host name, allowing connections to the first
       IP address for that host. Host names are fed through qual-
       ification using dns_ip4_qualify.

       tcpserver exits when it receives SIGTERM.

OPTIONS
       General options:

       -q     Quiet. Do not print error messages.

       -Q     (Default.) Print error messages.

       -v     Verbose.  Print error messages and status messages.

       Connection options:

       -c n   Do not handle more than n simultaneous connections.
              If there are n simultaneous copies of prog running,
              defer acceptance of a new connection until one copy
              finishes.   n  must be a positive integer. Default:
              40.

       -x cdb Follow the rules compiled into cdb by  tcprules(1).
              These  rules  may specify setting environment vari-
              ables or rejecting connections  from  bad  sources.
              You can rerun tcprules(1) to change the rules while
              tcpserver is running.

       -X     With -x cdb, allow connections even if cdb does not
              exist.  Normally tcpserver will drop the connection
              if cdb does not exist.




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tcpserver(1)                                         tcpserver(1)


       -B banner
              Write banner to the network immediately after  each
              connection is made.  tcpserver writes banner before
              looking  up  $TCPREMOTEHOST,  before   looking   up
              $TCPREMOTEINFO, and before checking cdb.  This fea-
              ture can be used to  reduce  latency  in  protocols
              where  the  client  waits  for  a greeting from the
              server.

       -g gid Switch group ID to gid after preparing  to  receive
              connections.  gid must be a positive integer.

       -u uid Switch  user  ID  to uid after preparing to receive
              connections.  uid must be a positive integer.

       -U     Same as -g $GID -u $UID. Typically  $GID  and  $UID
              are set by envuidgid(8).

       -1     After  preparing  to receive connections, print the
              local port number to standard output.

       -b n   Allow a backlog of approximately  n  TCP  SYNs.  On
              some  systems,  n is silently limited to 5. On sys-
              tems supporting SYN cookies, the backlog is irrele-
              vant.

       -o     Leave  IP  options  alone. If the client is sending
              packets along an IP source route, send packets back
              along the same route.

       -O     (Default.)  Kill IP options. A client can still use
              source routing to connect and  to  send  data,  but
              packets  will be sent back along the default route.

       -d     Delay sending data for a fraction of a second when-
              ever  the remote host is responding slowly. This is
              currently the default, but it may  not  be  in  the
              future; if you want it, set it explicitly.

       -D     Never delay sending data; enable TCP_NODELAY.

       Data-gathering options:

       -h     (Default.)  Look  up the remote host name in DNS to
              set the environment variable $TCPREMOTEHOST.

       -H     Do not look up the remote host name in DNS;  remove
              the  environment  variable $TCPREMOTEHOST. To avoid
              loops, you must use this option for servers on  TCP
              port 53.

       -p     Paranoid.  After looking up the remote host name in
              DNS, look up the IP addresses in DNS for that  host
              name,   and   remove   the   environment   variable



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tcpserver(1)                                         tcpserver(1)


              $TCPREMOTEHOST if none of the addresses  match  the
              client's IP address.

       -P     (Default.) Not paranoid.

       -l localname
              Do  not  look  up  the  local host name in DNS; use
              localname for the environment  variable  $TCPLOCAL-
              HOST.  A common choice for localname is 0. To avoid
              loops, you must use this option for servers on  TCP
              port 53.

       -r     (Default.)  Attempt  to  obtain $TCPREMOTEINFO from
              the remote host.

       -R     Do not attempt to obtain  $TCPREMOTEINFO  from  the
              remote  host.  To  avoid  loops,  you must use this
              option for servers on TCP ports 53 and 113.

       -t n   Give up on the  $TCPREMOTEINFO  connection  attempt
              after n seconds. Default: 26.

SEE ALSO
       tcprules(1),   tcprulescheck(1),   argv0(1),   fixcrio(1),
       recordio(1), rblsmtpd(1), tcpclient(1), who@(1), date@(1),
       finger@(1),  http@(1),  tcpcat(1),  mconnect(1), tcp-envi-
       ron(5)

       http://cr.yp.to/ucspi-tcp.html




























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