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YPBIND(8)		  BSD System Manager's Manual		     YPBIND(8)

     ypbind -- NIS domain binding daemon

     ypbind [-ypset] [-ypsetme]	[-s] [-m] [-S domainname,server1,server2,...]

     Ypbind is the process that	maintains NIS binding information. At startup,
     it	searches for an	NIS server responsible for serving the system's	de-
     fault domain (as set by the domainname(1) command)	using network broad-
     casts.  Once it receives a	reply, it will store the address of the	server
     and other information in a	special	file located in	/var/yp/binding.  The
     NIS routines in the standard C library can	then use this file when	pro-
     cessing NIS requests. There may be	several	such files since it is possi-
     ble for an	NIS client to be bound to more than one	domain.

     After a binding has been established, ypbind will send DOMAIN_NONACK re-
     quests to the NIS server at one minute intervals. If it fails to receive
     a reply to	one of these requests, ypbind assumes that the server is no
     longer running and	resumes	its network broadcasts until another binding
     is	established.  Ypbind will also log warning messages using the
     syslog(3) facility	each time it detects that a server has stopped re-
     sponding, as well as when it has bound to a new server.

     The following options are supported by ypbind:

     -ypset  It	is possible to force ypbind to bind to a particular NIS	server
	     host for a	given domain by	using the ypset(8) command. However,
	     ypbind refuses YPBINDPROC_SETDOM requests by default since	it has
	     no	way of knowing exactly who is sending them. Using the -ypset
	     flag causes ypbind	to accept YPBINDPROC_SETDOM requests from any
	     host. This	option should only be used for diagnostic purposes and
	     only for limited periods since allowing arbitrary users to	reset
	     the binding of an NIS client poses	a severe security risk.

	     This is similar to	the -ypset flag, except	that it	only permits
	     YPBINDPROC_SETDOM requests	to be processed	if they	originated
	     from the local host.

     -s	     Cause ypbind to run in secure mode: it will refuse	to bind	to any
	     NIS server	that is	not running as root (i.e. that is not using
	     privileged	TCP ports).

     -S	domainname,server1,server2,server3,...
	     Allow the system administrator to lock ypbind to a	particular do-
	     main and group of NIS servers. Up to ten servers can be speci-
	     fied.  There must not be any spaces between the commas in the do-
	     main/server specification.	This option is used to insure that the
	     system binds only to one domain and only to one of	the specified
	     servers, which is useful for systems that are both	NIS servers
	     and NIS clients: it provides a way	to restrict what machines the
	     system can	bind to	without	the need for specifying	the -ypset or
	     -ypsetme options, which are often considered to be	security
	     holes. The	specified servers must have valid entries in the local
	     /etc/hosts	file. IP addresses may be specified in place of	host-
	     names. If ypbind can't make sense ouf of the arguments, it	will
	     ignore the	-S flag	and continue running normally.

	     Note that ypbind will consider the	domainname specified with the
	     -S	flag to	be the system default domain.

     -m	     Cause ypbind to use a 'many-cast' rather than a broadcast for
	     choosing a	server from the	restricted mode	server list. In	many-
	     cast mode,	ypbind will transmit directly to the YPPROC_DO-
	     MAIN_NONACK procedure of the servers specified in the restricted
	     list and bind to the server that responds the fastest.  This mode
	     of	operation is useful for	NIS clients on remote subnets where no
	     local NIS servers are available. The -m flag can only be used in
	     conjunction with the -S flag above	(if used without the -S	flag,
	     it	has no effect).

     The ypbind	program	will not make continuous attempts to keep secondary
     domains bound.  If	a server for a secondary domain	fails to respond to a
     ping, ypbind will broadcast for a new server only once before giving up.
     If	a client program attempts to reference the unbound domain, ypbind will
     try broadcasting again. By	contrast, ypbind will automatically maintain a
     binding for the default domain whether client programs reference it ot

		   the files used to hold binding information for each NIS do-
     /etc/rc.conf  system configuration	file where the system default domain
		   and ypbind startup options are specified

     domainname(1), syslog(3), yp(4), ypserv(8), ypset(8)

     Theo de Raadt <>

BSD				 April 9, 1995				   BSD


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