1YPSERV(8)                    NIS Reference Manual                    YPSERV(8)
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NAME

6       ypserv - NIS Server
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SYNOPSIS

9       /usr/sbin/ypserv [-d] [-p port] [-f|--foreground]
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DESCRIPTION

12       The Network Information Service (NIS) provides a simple network lookup
13       service consisting of databases and processes. The databases are gdbm
14       files in a directory tree rooted at /var/yp.
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16       The ypserv daemon is typically activated at system startup.  ypserv
17       runs only on NIS server machines with a complete NIS database. On other
18       machines using the NIS services, you have to run ypbind as client or
19       under Linux you could use the libc with NYS support.  ypbind must run
20       on every machine which has NIS client processes; ypserv may or may not
21       be running on the same node, but must be running somewhere on the
22       network. On startup ypserv parses the file /etc/ypserv.conf.  It is
23       also possible to pass OPTIONS to ypserv using the environment variable
24       YPSERV_ARGS and this variable can be set in /etc/sysconfig/network.
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OPTIONS

27       -d, --debug
28           Causes the server to run in debugging mode. Normally, ypserv
29           reports only errors (access violations, dbm failures) using the
30           syslog(3) facility. In debug mode, the server does not background
31           itself and prints extra status messages to stderr for each request
32           that it revceives.
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34       -p, --port port
35           ypserv will bind itself to this port. This makes it possible to
36           have a router filter packets to the NIS ports, so that access to
37           the NIS server from hosts on the Internet can be restricted.
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39       -v, --version
40           Prints the version number
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42       -f, --foreground
43           will not put itself into background.
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SECURITY

46       In general, any remote user can issue an RPC to ypserv and retrieve the
47       contents of your NIS maps, if he knows your domain name. To prevent
48       such unauthorized transactions, ypserv supports a feature called
49       securenets which can be used to restrict access to a given set of
50       hosts. At startup ypserv will attempt to load the securenets
51       information from a file called /var/yp/securenets .  This file contains
52       entries that consist of a netmask and a network pair separated by white
53       spaces. Lines starting with “#” are considered to be comments.
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55       A sample securenets file might look like this:
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58               # allow connections from local host -- necessary
59               host 127.0.0.1
60               # same as 255.255.255.255 127.0.0.1
61               #
62               # allow connections from any host
63               # on the 131.234.223.0 network
64               255.255.255.0   131.234.223.0
65               # allow connections from any host
66               # between 131.234.214.0 and 131.234.215.255
67               255.255.254.0   131.234.214.0
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70       If ypserv receives a request from an address that fails to match a
71       rule, the request will be ignored and a warning message will be logged.
72       If the /var/yp/securenets file does not exist, ypserv will allow
73       connections from any host.
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75       In the /etc/ypserv.conf you could specify some access rules for special
76       maps and hosts. But it is not very secure, it makes the life only a
77       little bit harder for a potential hacker. If a mapname doesn´t match a
78       rule, ypserv will look for the YP_SECURE key in the map. If it exists,
79       ypserv will only allow requests on a reserved port.
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81       For security reasons, ypserv will only accept ypproc_xfr requests for
82       updating maps from the same master server as the old one. This means,
83       you have to reinstall the slave servers if you change the master server
84       for a map.
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BUGS

87       Sending the signal SIGHUP to the server can lead to a deadlock or
88       crash.
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FILES

91       /etc/ypserv.conf
92           configuration file.
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94       /var/yp/securenets
95           which hosts are allowed to contact ypserv.
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97       /etc/sysconfig/network
98           setting additional arguments to ypserv.
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SEE ALSO

101       domainname(1), ypcat(1), ypmatch(1), ypserv.conf(5), netgroup(5),
102       makedbm(8), revnetgroup(8), ypinit(8), yppoll(8), yppush(8), ypset(8),
103       ypwhich(8), ypxfr(8), rpc.ypxfrd(8)
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105       The Network Information Service (NIS) was formerly known as Sun Yellow
106       Pages (YP). The functionality of the two remains the same; only the
107       name has changed. The name Yellow Pages is a registered trademark in
108       the United Kingdom of British Telecommunications plc, and may not be
109       used without permission.
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AUTHOR

112       ypserv was written by Peter Eriksson <pen@lysator.liu.se>. Thorsten
113       Kukuk <kukuk@linux-nis.org> added support for master/slave server and
114       is the new Maintainer.
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118NIS Reference Manual              01/27/2010                         YPSERV(8)
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