After a binding has been established, ypbind will send YPPROC_DOMAIN requests to the current NIS server at 20 seconds intervals. If it doesnt get an response or the NIS server reports that he doesnt have this domain any longer, ypbind will search for a new NIS server. All 15 minutes ypbind will check to see if the current NIS server is the fastest. If it find a server which answers faster, it will switch to this server. You could tell ypbind to use network broadcasts to find a new server, what is insecure, or you could give it a list of known secure servers. In this case ypbind will send a ping to all servers and binds to first one which answers.
Unless the option -debug is used, ypbind detaches itself from the controlling terminal and puts itself into background. ypbind uses syslog(3) for logging errors and warnings. At startup or when receiving signal SIGHUP, ypbind parses the file /etc/yp.conf and tries to use the entries for its initial binding. Valid entries are
domain nisdomain server hostname Use server hostname for the domain nisdomain. You could have more then one entry of this type for a single domain.
domain nisdomain broadcast Use broadcast on the local net for domain nisdomain.
ypserver hostname Use server server for the local domain.
A broadcast entry in the configuration file will overwrite a ypserver/server entry and a ypserver/server entry broadcast. If all given server are down, ypbind will not switch to use broadcast. ypbind will try at first /etc/hosts and then DNS for resolving the hosts names from /etc/yp.conf. If ypbind couldnt reconfigure the search order, it will use only DNS. If DNS isnt available, you could only use IP-addresses in /etc/hosts. ypbind could only reconfigure the search order with glibc 2.x. If the -broadcast option is specified, ypbind will ignore the configuration file. If the file does not exist or if there are no valid entries, ypbind exit.
This ypbind is a special version which uses pthreads. It will start 2 more threads. The master process services RPC requests asking for binding info. The first thread initializes the binding and checks it periodically. Upon failure, the binding is invalidated and the process tries again to find a valid server. The second thread will handle all the signals.
|Send a broadcast to request the information needed to bind to a specific NIS server. With this option, /etc/yp.conf will be ignored.|
|-ypset||Allow root from any remote machine to change the binding for a domain via the ypset(8) command. By default, no one can change the binding. This option is really insecure. If you change a binding for a domain, all the current known servers for this domain will be forgotten. If the new server goes down, ypbind will use the old searchlist.|
|The same as -ypset, but only root on the local machine is allowed to chang the binding. Such requests are only allowd from loopback.|
|-c||ypbind only checks if the config file has syntax errors and exits.|
|-debug||starts ypbind in debug mode. ypbind will not put itself into background, and error messages and debug output are written to standard error.|
|Causes ypbind to syslog(2) any and all changes in the server its bound to.|
|lets ypbind accept answers from servers running on an illegal port number. This should usually be avoided, but is required by some ypserv(8) versions.|
|ypbind will not check if the binding is alive. This option is for use with dialup connections to prevent ypbind from keeping the connection unnessecarily open or causing autodials.|
|ypbind will bind itself to this port. This makes it possible to have a router filter packets to the NIS ports, so that access to this service from hosts on the Internet can be restricted.|
|ypbind will use configfile and not /etc/yp.conf|
|ypbind will only bind to the loopback device and is not reacheable from a remote network.|
|The default value for ypbind to check, if a NIS server is still reacheable, is 20 seconds. With this options another frequency in seconds can be specified.|
|Prints the version number|
|binding file containing information about each NIS domain.|
|contains the process id of the currently running ypbind master process.|