10.2;tcpd (TCP daemon), revision 2.0, 89/03/30 tcpd - TCP/IP protocol server usage: 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, ping; Configuring and Managing TCP/IP.