ypserv(1M)                       UNIX System V                       ypserv(1M)


NAME
      ypserv, ypbind - NIS server and binder processes

SYNOPSIS
      /usr/lib/netsvc/yp/ypserv

      /usr/lib/netsvc/yp/ypbind [ -ypset |-ypsetme ]

DESCRIPTION
      The NIS provides a simple network lookup service consisting of databases
      and processes.  The databases are dbm(3) files in a directory tree rooted
      at /var/yp.  These files are described in ypfiles(4).  The processes are
      /usr/lib/netsvc/yp/ypserv, the NIS database lookup server, and
      /usr/lib/netsvc/yp/ypbind, the NIS binder.  The programmatic interface to
      NIS is described in ypclnt(3N).  Administrative tools are described in
      yppush(1M), ypxfr(1M), yppoll(1M), ypwhich(1), and ypset(1M).  Tools to
      see the contents of NIS maps are described in ypcat(1), and ypmatch(1).
      Database generation and maintenance tools are described in ypinit(1M),
      ypmake(1M), and makedbm(1M).

      Both ypserv and ypbind are daemon processes typically activated at system
      startup time.  ypserv runs only on NIS server machines with a complete
      NIS database.  ypbind runs on all machines using NIS services, both NIS
      servers and clients.

      The ypserv daemon's primary function is to look up information in its
      local database of NIS maps.  Communication to and from ypserv is by means
      of RPC calls.  Lookup functions are described in ypclnt(3N), and are
      supplied as C-callable functions in the NIS library.  There are four
      lookup functions, all of which are performed on a specified map within
      some NIS domain:  Match, "Get_first", "Get_next", and "Get_all".  The
      Match operation takes a key, and returns the associated value.  The
      "Get_first" operation returns the first key-value pair from the map, and
      "Get_next" can be used to enumerate the remainder.  "Get_all" ships the
      entire map to the requester as the response to a single RPC request.

      Two other functions supply information about the map, rather than map
      entries:  "Get_order_number", and "Get_master_name".  In fact, both order
      number and master name exist in the map as key-value pairs, but the
      server will not return either through the normal lookup functions.  If
      you examine the map with makedbm(1M), however, they will be visible.

      The function of ypbind is to remember information that lets client
      processes on a single node communicate with some ypserv process.  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.

      The information ypbind remembers is called a binding-the association of a
      domain name with a NIS server.




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ypserv(1M)                       UNIX System V                       ypserv(1M)


      The process of binding is driven by client requests.  As a request for an
      unbound domain comes in, the ypbind process steps through the ypservers
      list (last entry first) trying to find a ypserv process that serves maps
      within that domain.  There must be a ypserv process on at least one of
      the hosts in the ypservers file.  Once a domain is bound by a particular
      ypbind, that same binding is given to every client process on the node.
      The ypbind process on the local node or a
      remote node may be queried for the binding of a particular domain by
      using the ypwhich(1) command.

      If ypbind is unable to speak to the ypserv process it is bound to, it
      marks the domain as unbound, tells the client process that the domain is
      unbound, and tries to bind the domain once again.  Requests received for
      an unbound domain will wait until the domain requested is bound.  In
      general, a bound domain is marked as unbound when the node running ypserv
      crashes or gets overloaded.  In such a case, ypbind will try to bind to
      another NIS server listed in /var/yp/binding/domainname/ypservers.

      ypbind also accepts requests to set its binding for a particular domain.
      The request is usually generated by the NIS subsystem itself.  ypset(1M)
      is a command to access the "Set_domain" facility.  Note: the Set Domain
      procedure only accepts requests from processes with appropriate
      privileges, and the -ypset or -ypsetme flags must have been set for
      ypbind.

      The following options are available for the ypbind command only:

      -ypset      Allow any user to call ypset(1M).  By default, no one can
                  call ypset(1M).

      -ypsetme    Only allow root on local machines to call ypset(1M).  By
                  default, no one can call ypset(1M).

FILES
      If the file /var/yp/ypserv.log exists when ypserv starts up, log
      information will be written to this file when error conditions arise.
      /var/yp
      /var/yp/binding/ypdomain/ypservers

SEE ALSO
      makedbm(1M), ypcat(1), ypinit(1M), ypmake(1M), ypmatch(1), yppoll(1M),
      yppush(1M), ypset(1M), ypwhich(1), ypxfr(1M), dbm(3X), ypclnt(3N),
      ypfiles(4)

NOTES
      Both ypbind and ypserv support multiple domains.  The ypserv process
      determines the domains it serves by looking for directories of the same
      name in the directory /var/yp.  Additionally, the ypbind process can
      maintain bindings to several domains and their servers.





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