ypserv - NIS server


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


   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.


   -d --debug [path]
          Causes the server to run in  debugging  mode.  Normally,  ypserv
          reports  only errors (access violations, dbm failures) using the
          syslog(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


   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  starting
   with ``#'' are considered to be comments.

   A sample securenets file might look like this:

          # allow connections from local host -- necessary
          # same as
          # allow connections from any host
          # on the network

          # allow connections from any host
          # between and

   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.


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


   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.


   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.


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