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YPSERV(8)		FreeBSD	System Manager's Manual		     YPSERV(8)

     ypserv -- YP server daemon

     ypserv [-1dx] [-a aclfile]

     ypserv is a fundamental part of the network information system called YP.
     This server provides information from YP maps to the YP clients on	the

     A YP map is stored	on the server as a Berkeley database.  A number	of YP
     maps are grouped together in a domain.  ypserv determines the domains it
     serves by looking for a directory with the	domain name in /var/yp.

     YP	hasn't been known for high security through the	years.	In recent
     years security has	improved by restricting	access to the server.  In
     SunOS 4.1 has a new file occurred named /var/yp/securenet.	 It contains
     networks the server can assume is secure.	For information	about the file
     format, see securenet(5).

     Before the	author of this server had seen securenet(5) another format,
     ypserv.acl(5), was	implemented.  This file	format makes it	possible to
     allow and deny hosts and networks access to the server.  This file	can
     have any name since it's given by the argument to -a (use full path).

     If	a host isn't secure, all queries to the	server will result in a
     YP_NODOM result.

     If	the file /var/yp/ypserv.log exists then	messages will be written to
     the file.

     If	a directory named the same as the system domainname exists in /var/yp
     (i.e., the	domainname is "foo" and	the directory /var/yp/foo exists),
     then ypserv will be automatically started at boot time.

     On	receipt	of a hangup signal, SIGHUP, ypserv will	reopen the log file
     and reread	its configuration, including both the map files	and the
     ypserv.acl(5) or securenet(5) configuration file.

     The options are as	follows:

     -1	     Allow ypserv to answer old	YP version 1 requests.

     -a	aclfile
	     Don't use /var/yp/securenet.  Use another file with a different
	     file format.  For further information see ypserv.acl(5).

     -d	     Use Internet Domain Name System.  If a query to map
	     "hosts.byname" or "hosts.byaddr" fails, make a DNS	query and re-
	     turn the result if	successful.  Alternately, if these maps	were
	     built on the YP master using makedbm -b then DNS queries will be
	     done without needing to specify -d.

     -x	     Terminate the server after	processing aclfile or


     dbopen(3),	securenet(5), ypserv.acl(5), Makefile.yp(8), yp(8), ypbind(8)

     Mats O Jansson <>

FreeBSD	13.0		       November	1, 2020			  FreeBSD 13.0


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