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

NAME

       tcpsvd - TCP/IP service daemon

SYNOPSIS

       tcpsvd [-hpEvv] [-c n] [-C n:msg] [-b n] [-u user] [-l name] [-i dir|-x cdb] [ -t sec] host port prog

DESCRIPTION

       tcpsvd creates a TCP/IP socket, binds it to the address host:port, and listens on the socket for incoming connections.

       On  each incoming connection, tcpsvd conditionally runs a program, with standard input reading from the socket, and standard output writing
       to the socket, to handle this connection.  tcpsvd keeps listening on the socket for new connections, and can  handle  multiple  connections
       simultaneously.

       tcpsvd  optionally checks for special instructions depending on the IP address or hostname of the client that initiated the connection, see
       ipsvd-instruct(5).

OPTIONS

       host   host either is a hostname, or a dotted-decimal IP address, or 0.	If host is 0, tcpsvd accepts connections to any local IP address.

       port   tcpsvd accepts connections to host:port.	port may be a name from /etc/services or a number.

       prog   prog consists of one or more arguments.  For each connection, tcpsvd normally runs prog, with file descriptor  0	reading  from  the
	      network,	and file descriptor 1 writing to the network.  By default it also sets up TCP-related environment variables, see tcp-envi-
	      ron(5)

       -i dir read instructions for handling new connections from the instructions directory dir.  See ipsvd-instruct(5) for details.

       -x cdb read instructions for handling new connections from the constant database cdb.  The constant database normally is  created  from	an
	      instructions directory by running ipsvd-cdb(8).

       -t sec timeout.	 This  option  only  takes effect if the -i option is given.  While checking the instructions directory, check the time of
	      last access of the file that matches the clients address or hostname if any, discard and remove  the  file  if  it  wasn't  accessed
	      within the last sec seconds; tcpsvd does not discard or remove a file if the user's write permission is not set, for those files the
	      timeout is disabled.  Default is 0, which means that the timeout is disabled.

       -l name
	      local hostname.  Do not look up the local hostname in DNS, but use name as hostname.  This option must be set if tcpsvd  listens	on
	      port 53 to avoid loops.

       -u [:]user[:group]
	      drop  permissions.  Set uid and gid to the user's uid and gid, as found in /etc/passwd, before running prog.  If user is followed by
	      a colon and a group, set the gid to group's gid, as found in /etc/group, instead of user's gid.  If group consists of a  colon-sepa-
	      rated  list  of group names, set the group ids of all listed groups.  If user is prefixed with a colon, the user and all group argu-
	      ments are interpreted as uid and gids respectively, and not looked up in the password or group file.  All supplementary  groups  are
	      removed.

       -c n   concurrency.   Handle  up  to n connections simultaneously.  Default is 30.  If there are n connections active, tcpsvd defers accep-
	      tance of a new connection until an active connection is closed.

       -C n[:msg]
	      per host concurrency.  Allow only up to n connections from the same IP address simultaneously.  If there are  n  active  connections
	      from  one  IP  address, new incoming connections from this IP address are closed immediately.  If n is followed by :msg, the message
	      msg is written to the client if possible, before closing the connection.	By default msg is empty.  See ipsvd-instruct(5)  for  sup-
	      ported escape sequences in msg.

	      For  each accepted connection, the current per host concurrency is available through the environment variable TCPCONCURRENCY.  n and
	      msg can be overwritten by ipsvd(7) instructions, see ipsvd-instruct(5).  By default tcpsvd doesn't keep track of connections.

       -h     Look up the client's hostname in DNS.

       -p     paranoid.  After looking up the client's hostname in DNS, look up the IP addresses in DNS for that hostname, and	forget	about  the
	      hostname if none of the addresses match the client's IP address.	You should set this option if you use hostname based instructions.
	      The -p option implies the -h option.

       -b n   backlog.	Allow a backlog of approximately n TCP SYNs.  On some systems n is silently limited.  Default is 20.

       -E     no special environment.  Do not set up TCP-related environment variables.

       -v     verbose.	Print verbose messsages to standard output.

       -vv    more verbose.  Print more verbose messages to standard output.

SEE ALSO

       ipsvd(7), sslsvd(8), udpsvd(8), ipsvd-instruct(5), ipsvd-cdb(8), sslio(8)

       http://smarden.org/ipsvd/

AUTHOR

       Gerrit Pape <pape@smarden.org>

																	 tcpsvd(8)