1.\" Copyright (c) 1995, 1996
2.\"	Bill Paul <wpaul@ctr.columbia.edu>.  All rights reserved.
3.\"
4.\" Redistribution and use in source and binary forms, with or without
5.\" modification, are permitted provided that the following conditions
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14.\"	This product includes software developed by Bill Paul.
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31.\" $FreeBSD: src/usr.sbin/rpc.ypxfrd/rpc.ypxfrd.8,v 1.9.2.3 2003/03/11 22:31:32 trhodes Exp $
32.\" $DragonFly: src/usr.sbin/rpc.ypxfrd/rpc.ypxfrd.8,v 1.3 2004/03/11 12:29:00 hmp Exp $
33.\"
34.Dd June 2, 1996
35.Dt RPC.YPXFRD 8
36.Os
37.Sh NAME
38.Nm rpc.ypxfrd
39.Nd "NIS map transfer server"
40.Sh SYNOPSIS
41.Nm
42.Op Fl p Ar path
43.Sh DESCRIPTION
44The
45.Nm
46utility is used to speed up the distribution of very large NIS maps
47from NIS master to NIS slave servers.
48The normal method for transfering
49maps involves several steps:
50.Bl -bullet -offset indent
51.It
52The master server calls
53.Xr yppush 8
54to inform the slave servers to start a transfer.
55.It
56The slave servers invoke
57.Xr ypxfr 8 ,
58which reads the entire contents of a map from the master server
59using the yp_all() function.
60.It
61The
62.Xr ypxfr 8
63program then creates a new map database file by using the
64.Xr db 3
65library hash method to store the data that it receives from the server.
66.It
67When all the data has been retrieved,
68.Xr ypxfr 8
69moves the new file into place and sends
70.Xr ypserv 8
71on the local machine a YPPROC_CLEAR to tell it to refresh its
72database handles.
73.El
74.Pp
75This process can take several minutes when there are very large
76maps involved.
77For example: a passwd database with several tens of
78thousands of entries can consume several megabytes of disk space,
79and it can take the
80.Xr db 3
81library package a long time to sort and store all the records
82in a hash database.
83Consider also that there are two sets of map
84files:
85.Pa master.passwd.by{name,uid}
86and
87.Pa passwd.by{name,uid} .
88.Pp
89The
90.Nm
91utility speeds up the transfer process by allowing NIS slave servers to
92simply copy the master server's map files rather than building their
93own from scratch.
94Simply put,
95.Nm
96implements an RPC-based file transfer protocol.
97Transfering even
98a multi-megabyte file in this fashion takes only a few seconds compared
99to the several minutes it would take even a reasonably fast slave server
100to build a new map from scratch.
101.Pp
102The
103.Nm
104utility uses the same access restriction mechanism as
105.Xr ypserv 8 .
106This means that slave servers will only be permitted to transfer
107files if the rules in the
108.Xr securenets 5
109database permit it.
110Furthermore, only slave servers using reserved
111ports will be allowed to transfer the
112.Pa master.passwd
113maps.
114.Sh OPTIONS
115The following option is available:
116.Bl -tag -width indent
117.It Fl p Ar path
118This option can be used to override the default path to
119the location of the NIS
120map databases.
121The compiled-in default path is
122.Pa /var/yp .
123.El
124.Sh FILES
125.Bl -tag -width Pa -compact
126.It Pa /var/yp/[domainname]/[maps]
127The NIS maps for a particular NIS domain.
128.El
129.Sh SEE ALSO
130.Xr yp 8 ,
131.Xr yppush 8 ,
132.Xr ypserv 8 ,
133.Xr ypxfr 8
134.Sh BUGS
135The
136.Dx
137.Nm ypxfrd
138protocol is not compatible with that used by SunOS.
139This is unfortunate
140but unavoidable: Sun's protocol is not freely available, and even if it
141were it would probably not be useful since the SunOS NIS v2 implementation
142uses the original ndbm package for its map databases whereas the
143.Dx
144implementation uses Berkeley DB.
145These two packages use vastly different
146file formats.
147Furthermore, ndbm is byte-order sensitive and not very
148smart about it, meaning that am ndbm database created on a big endian
149system can't be read on a little endian system.
150.Sh AUTHORS
151.An Bill Paul Aq wpaul@ctr.columbia.edu
152