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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,...]

     The ypbind	utility	is the process that maintains NIS binding information.
     At	startup, it searches for an NIS	server responsible for serving the
     system's default domain (as set by	the domainname(1) command) using net-
     work broadcasts.  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 processing NIS requests.  There may	be several such	files
     since it is possible for an NIS client to be bound	to more	than one do-

     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.  The ypbind utility 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 available:

     -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	speci-
	     fied servers, which is useful for systems that are	both NIS
	     servers and NIS clients: it provides a way	to restrict what ma-
	     chines the	system can bind	to without the need for	specifying the
	     -ypset or -ypsetme	options, which are often considered to be se-
	     curity holes.  The	specified servers must have valid entries in
	     the local /etc/hosts file.	 IP addresses may be specified in
	     place of hostnames.  If ypbind can't make sense out of the	argu-
	     ments, 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	utility	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(8), ypserv(8), ypset(8)

     Theo de Raadt <>

BSD				 April 9, 1995				   BSD


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