YPSERV(8)							 Reference Manual							 YPSERV(8)

NAME

       ypserv - NIS server

SYNOPSIS

       /usr/sbin/ypserv [ -d [ path ] ] [ -p port ]

DESCRIPTION

       The  Network  Information  Service (NIS) provides a simple network lookup service consisting of databases and processes.  The databases are
       gdbm files in a directory tree rooted at /var/yp.

       The ypserv daemon is typically activated at system startup.  ypserv runs only on NIS server machines with a complete NIS database. On other
       machines  using the NIS services, you have to run ypbind as client or under Linux you could use the libc with NYS support.  ypbind must run
       on every machine which has NIS client processes; ypserv may or may not be running on the same node, but must be running	somewhere  on  the
       network. On startup or when receiving the signal SIGHUP, ypserv parses the file /etc/ypserv.conf.

OPTIONS

       -d --debug [path]
	      Causes  the  server  to run in debugging mode. Normally, ypserv reports only errors (access violations, dbm failures) using the sys-
	      log(3) facility. In debug mode, the server does not background itself and prints extra status messages to stderr	for  each  request
	      that it revceives.  path is an optionally parameter.  ypserv is using this directory instead of /var/yp

       -p --port port
	      ypserv  will  bind  itself to this port.	This makes it possible to have a router filter packets to the NIS ports, so that access to
	      the NIS server from hosts on the Internet can be restricted.

       -v --version
	      Prints the version number

SECURITY

       In general, any remote user can issue an RPC to ypserv and retrieve the contents of your NIS maps, if he knows your domain name. To prevent
       such  unauthorized  transactions, ypserv supports a feature called securenets which can be used to restrict access to a given set of hosts.
       At  startup  or	when  arriving	the  SIGHUP  Signal,  ypserv  will  attempt  to  load  the  securenets	information  from  a  file  called
       /etc/ypserv.securenets  .  This file contains entries that consist of a netmask and a network pair separated by white spaces.  Lines start-
       ing with ``#'' are considered to be comments.

       A sample securenets file might look like this:

	      # allow connections from local host -- necessary
	      host 127.0.0.1
	      # same as 255.255.255.255 127.0.0.1
	      #
	      # allow connections from any host
	      # on the 131.234.223.0 network
	      255.255.255.0   131.234.223.0
	      # allow connections from any host
	      # between 131.234.214.0 and 131.234.215.255
	      255.255.254.0   131.234.214.0

       If ypserv receives a request from an address that fails to match a rule, the request will be ignored and a warning message will be  logged.
       If the /etc/ypserv.securenets file does not exist, ypserv will allow connections from any host.

       In the /etc/ypserv.conf you could specify some access rules for special maps and hosts. But it is not very secure, it makes the life only a
       little bit harder for a potential hacker. If a mapname doesn't match a rule, ypserv will look for the YP_SECURE	key  in  the  map.  If	it
       exists, ypserv will only allow requests on a reserved port.

       For security reasons, ypserv will only accept ypproc_xfr requests for updating maps from the same master server as the old one. This means,
       you have to reinstall the slave servers if you change the master server for a map.

FILES

       /etc/ypserv.conf /etc/ypserv.securenets

SEE ALSO

       domainname(1), ypcat(1), ypmatch(1), ypserv.conf(5), netgroup(5), makedbm(8), revnetgroup(8), ypinit(8),  yppoll(8),  yppush(8),  ypset(8),
       ypwhich(8), ypxfr(8), rpc.ypxfrd(8)

       The Network Information Service (NIS) was formerly known as Sun Yellow Pages (YP).  The functionality of the two remains the same; only the
       name has changed.  The name Yellow Pages is a registered trademark in the United Kingdom of British Telecommunications plc, and may not	be
       used without permission.

AUTHOR

       ypserv was written by Peter Eriksson <pen@lysator.liu.se>.  Thorsten Kukuk <kukuk@suse.de> added support for master/slave server and is the
       new Maintainer.

YP Server							    August 2001 							 YPSERV(8)