TCPD(8)                         Domain/OS BSD                          TCPD(8)



NAME
     tcpd - TCP/IP protocol server

SYNOPSIS
     /etc/tcpd [ -a] [-b] [-d<mask>] [-p<time>] [-t<ipttl>] [-w<window>]

DESCRIPTION
     Invoking tcpd, the TCP/IP protocol server or daemon, enables a node's
     TCP/IP socket-call interface and initializes several internal tables
     required for operation of the protocols. The tcpd daemon must be run on
     every node that uses TCP/IP.  Normally, tcpd is invoked by the node's
     startup file, /etc/rc.local.

     Options available with this command allow you to define certain
     parameters of the protocols.

OPTIONS
     -a          Suppress delayed packet acknowledgements (ACKs), the default
                 condition.  Delayed ACKs is a performance optimization
                 feature for TCP which allows a receiver to delay until 33% of
                 the maximum window size offered can be uncovered (but in no
                 case to wait longer than 0.25 seconds) before it acknowledges
                 received packets.

     -b          Enable directed broadcasts according to the Internet protocol
                 for gateway routers (RFC 1009). Invoke the TCP/IP server with
                 -b when you plan to run an application that relies on
                 directed broadcasts. Normally, the TCP/IP server broadcasts
                 messages sent by applications in its own locally connected
                 network.  With directed broadcasts, the TCP/IP server
                 delivers broadcasts to its network (or a subnet within its
                 network) that have been sent by applications in other
                 Internet networks.

     -p<time>    Set gateway ping interval in seconds. The value must be
                 expressed in hexadecimal and can range from 0 to A.  Default
                 value is 4 seconds.  Setting the interval to 0 inhibits
                 pinging.  TCP issues an ICMP Echo Request (ping) to local
                 hosts and gateways at the specified interval to verify their
                 continued operation. Any gateway that fails to respond after
                 three tries is moved to the end of the node's routing table.

     -t<ipttl>   Set the IP parameter, packet maximum time to live.  The value
                 must be expressed in hexadecimal and can range from 1 to FF.
                 Default value is 1E.

     -w<window>  Set the receive window size (a TCP flow control parameter) in
                 octets. The value must be expressed in HEX and can range from
                 1 to 239C.  Default value is 239C.

     -d<mask>    Display debugging information as defined by the 16-bit mask.
                 See the table below for a description of the debug
                 information that can be requested.  Add bit values to request
                 several types of information.

          Bit Value          Debug Information

          0001 (default)     General information
          0002               IP level information
          0004               ARP information
          0008               TCP information

          0020               UDP information
          0200               Broadcasts
          1000               TCP finite state machine information
          2000               Device level information
          4000               Additional detail at any level
          foff               All available debug information
                             except broadcasts

SEE ALSO
     netstat(1), ping(8);
     Configuring and Managing TCP/IP.