BINDADDR (JANUS DEFINE parameter)

BINDADDR xxx.xxx.xxx.xxx — Bind port to a particular IP address

BINDADDR is a parameter on JANUS DEFINE, which defines and sets characteristics of a Janus port.

This parameter specifies the IP address to which the port will be bound, if the host (machine) on which Model 204 is running supports multiple IP addresses. The IP address must be an IP address of the host. If BINDADDR is not specified, the port binds the port number for all IP addresses associated with the host; that is, it can be accessed via any IP address associated with the host.

This parameter only really makes sense on a host with more than one IP address. For example, if a host on which an Online is running has IP addresses 198.242.244.47 and 198.242.244.130, a BINDADDR 198.242.244.47 specification indicates that the port can only be reached through IP address 198.242.244.47.

This parameter is especially useful for allowing a single mainframe host or even an Online to act as more than one web server without the inconvenience of having port numbers on URLs. This can be done because there can be multiple port 80's (the default web port number) on the host, each accessed by its indicated BINDADDR. The separate IP addresses could, in turn, be associated with different DNS host names even though these separate names refer to the same underlying machine.

Note that there is not likely to be much, if any, performance benefit to having multiple Janus ports with the same port number but different BINDADDRs in the same Online. There might certainly be, however, some organizational advantages to running such a configuration.

Valid for all port types.

See also

• List of Janus commands
• List of JANUS DEFINE parameters