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.