Usually the gdomap daemon is started at system boot time and binds itself to port 538. See the GNUstep Build Guide for a sample startup script.
By default gdomap probes every machine on the local network to see if there is a copy of gdomap running on it. This is done for class-C networks and subnets of class-C networks. If your host is on a class-B or class-A net then the default behaviour is to treat it as a class-C net and probe only the hosts that would be expected on a class-C network of the same number.
If you are running on a class-A or class-B network, or if your net has a large number of hosts which will not have gdomap on them - you may want to supply a configuration file listing the hosts to be probed explicitly, rather than getting gdomap to probe all hosts on the local net.
You may also want to supply the configuration file so that hosts which are not actually on your local network can still be found when your code tries to connect to a host using @"*" as the host name. NB. this functionality does not exist in OpenStep.
A configuration file consists of a list of IP addresses to be probed. The IP addresses should be in standard 'dot' notation, one per line. Empty lines are permitted in the configuration file. Anything on a line after a hash ('#') is ignored. You tell gdomap about the config file with the '-c' command line option.
gdomap uses the SIOCGIFCONF ioctl to build a list of IP addresses and netmasks for the network interface cards on your machine. On some operating systems, this facility is not available (or is broken), so you must tell gdomap the addresses and masks of the interfaces using the '-a' command line option. The file named with '-a' should contain a series of lines with space separated pairs of addresses and masks in 'dot' notation. You must NOT include loopback interfaces in this list. If you want to support broadcasting of probe information on a network, you may supply the broadcast address as a third item on the line. If your operating system has some other method of giving you a list of network interfaces and masks, please send me example code so that I can implement it in gdomap.
gdomap -N lists all registered names on the local host.
gdnc(1), GNUstep(7), gpbs(1)
The GNUstep Build Guide example rc script: <http://gnustep.made-it.com/BuildGuide/index.html#GNUSTEP.SERVICES>
This manual page first appeared in gnustep-base 1.7.1 (June 2003).
This manual page was put together by Martin Brecher <email@example.com>.