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YPBIND(8)		FreeBSD	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

     After a binding has been established, ypbind will send DOMAIN_NONACK
     requests 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 mes-
     sages using the syslog(3) facility	each time it detects that a server has
     stopped responding, 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
	     domain and	group of NIS servers.  Up to ten servers can be	speci-
	     fied.  There must not be any spaces between the commas in the
	     domain/server specification.  This	option is used to ensure 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
	     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 hostnames.  If ypbind cannot 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_DOMAIN_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	sub-
	     nets where	no local NIS servers are available.  The -m flag can
	     only be used in conjunction with the -S flag above	(if used with-
	     out 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
     /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 <>

FreeBSD	Ports 11.2		 April 9, 1995		    FreeBSD Ports 11.2


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