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  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

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 starting 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.