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RPC.YPXFRD(8)		FreeBSD	System Manager's Manual		 RPC.YPXFRD(8)

     rpc.ypxfrd	-- NIS map transfer server

     rpc.ypxfrd	[-p path]

     The rpc.ypxfrd utility is used to speed up	the distribution of very large
     NIS maps from NIS master to NIS slave servers.  The normal	method for
     transferring maps involves	several	steps:

	   +o   The master server calls yppush(8) to inform the slave servers
	       to start	a transfer.

	   +o   The slave servers invoke	ypxfr(8), which	reads the entire con-
	       tents of	a map from the master server using the yp_all()	func-

	   +o   The ypxfr(8) program then creates a new map database file by
	       using the db(3) library hash method to store the	data that it
	       receives	from the server.

	   +o   When all	the data has been retrieved, ypxfr(8) moves the	new
	       file into place and sends ypserv(8) on the local	machine	a
	       YPPROC_CLEAR to tell it to refresh its database handles.

     This process can take several minutes when	there are very large maps
     involved.	For example: a passwd database with several tens of thousands
     of	entries	can consume several megabytes of disk space, and it can	take
     the db(3) library package a long time to sort and store all the records
     in	a hash database.  Consider also	that there are two sets	of map files:{name,uid}	and{name,uid}.

     The rpc.ypxfrd utility speeds up the transfer process by allowing NIS
     slave servers to simply copy the master server's map files	rather than
     building their own	from scratch.  Simply put, rpc.ypxfrd implements an
     RPC-based file transfer protocol.	Transferring even a multi-megabyte
     file in this fashion takes	only a few seconds compared to the several
     minutes it	would take even	a reasonably fast slave	server to build	a new
     map from scratch.

     The rpc.ypxfrd utility uses the same access restriction mechanism as
     ypserv(8).	 This means that slave servers will only be permitted to
     transfer files if the rules in the	securenets database permit it (see
     ypserv(8) for more	information on securenets).  Furthermore, only slave
     servers using reserved ports will be allowed to transfer the
     master.passwd maps.

     The following option is available:

     -p	path
	     This option can be	used to	override the default path to the loca-
	     tion of the NIS map databases.  The compiled-in default path is

     /var/yp/[domainname]/[maps]       The NIS maps for	a particular NIS

     yp(8), yppush(8), ypserv(8), ypxfr(8)

     Bill Paul <>

     The FreeBSD ypxfrd	protocol is not	compatible with	that used by SunOS.
     This is unfortunate but unavoidable: Sun's	protocol is not	freely avail-
     able, and even if it were it would	probably not be	useful since the SunOS
     NIS v2 implementation uses	the original ndbm package for its map data-
     bases whereas the FreeBSD implementation uses Berkeley DB.	 These two
     packages use vastly different file	formats.  Furthermore, ndbm is byte-
     order sensitive and not very smart	about it, meaning that am ndbm data-
     base created on a big endian system cannot	be read	on a little endian

FreeBSD	10.1			 June 2, 1996			  FreeBSD 10.1


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