tcpserver(1)                                                  General Commands Manual                                                 tcpserver(1)

NAME

       tcpserver - accept incoming TCP connections

SYNOPSIS

       tcpserver [ -146jpPhHrRoOdDqQv ] [ -climit ] [ -xrules.cdb ] [ -Bbanner ] [ -ggid ] [ -uuid ] [ -bbacklog ] [ -llocalname ] [ -ttimeout ] [
       -Iinterface ] host port program [ arg ...  ]

DESCRIPTION

       tcpserver waits for connections from TCP clients.  For each connection, it runs program with the given arguments, with descriptor 0 reading
       from the network and descriptor 1 writing to the network.

       The  server's  address  is given by host and port.  host can be 0, allowing connections from any host; or a particular IP address, allowing
       connections only to that address; or a host name, allowing connections to the first IP address for that host.  port may be a  numeric  port
       number or a port name.  If port is 0, tcpserver will choose a free port.

       tcpserver sets up several environment variables, as described in tcp-environ(5).

       tcpserver exits when it receives SIGTERM.

OPTIONS

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

       -xrules.cdb
              Follow the rules compiled into rules.cdb by tcprules.  These rules may specify setting environment variables  or  rejecting  connec-
              tions from bad sources.

              tcpserver does not read rules.cdb into memory; you can rerun tcprules to change tcpserver's behavior on the fly.

       -Bbanner
              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 rules.cdb.

              This feature can be used to reduce latency in protocols where the client waits for a greeting from the server.

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

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

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

       -4     Fall back to IPv4 sockets.  This is necessary for terminally broken systems like OpenBSD which will not let IPv6 sockets connect  to
              V4-mapped  IPv6  addresses.  Please note that this also applies to DNS lookups, so you will have to use an DNS resolver with an IPv6
              address to accept IPv6 connections.  Use DNSCACHEIP to set the DNS resolver IP dynamically.

       -6     Force IPv6 mode in UCSPI environment variables, even for IPv4 connections.  This will set $PROTO to TCP6 and  put  IPv4-mapped  IPv6
              addresses in TCPLOCALIP and TCPREMOTEIP.

       -Iinterface
              Bind  to  the  network  interface  interface  ("eth0"  on  Linux, for example).  This is only defined and needed for IPv6 link-local
              addresses.

       -bbacklog
              Allow up to backlog simultaneous SYN_RECEIVEDs.  Default: 20.  On some systems, backlog is silently limited to 5.  See listen(2) for
              more details.

       -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     (Default.)  Delay sending data for a fraction of a second whenever the remote host is responding slowly, to make better use  of  the
              network.

       -D     Never delay sending data; enable TCP_NODELAY.  This is appropriate for interactive connections.

       -q     Quiet.  Do not print any messages.

       -Q     (Default.)  Print error messages.

       -v     Verbose.  Print all available messages.

DATA-GATHERING OPTIONS
       -p     Paranoid.   After  looking up the remote host name, look up the IP addresses for that name, and make sure one of them matches TCPRE-
              MOTEIP.  If none of them do, unset TCPREMOTEHOST.

       -P     (Default.)  Not paranoid.

       -h     (Default.)  Look up the remote host name and set TCPREMOTEHOST.

       -H     Do not look up the remote host name.

       -llocalname
              Do not look up the local host name; use localname for TCPLOCALHOST.

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

       -R     Do not attempt to obtain TCPREMOTEINFO from the remote host.

       -ttimeout
              Give up on the TCPREMOTEINFO connection attempt after timeout seconds. Default: 26.

SEE ALSO

       argv0(1), fixcr(1), recordio(1), tcpclient(1), tcprules(1), listen(2), tcp-environ(5)

                                                                                                                                      tcpserver(1)