NAME

       rpc.ypxfrd - NIS map transfer server

SYNOPSIS

       /usr/sbin/rpc.ypxfrd [-d path] [-p port] [--debug]

       /usr/sbin/rpc.ypxfrd --version

DESCRIPTION

       rpc.ypxfrd is used for speed up the transfer of very large NIS maps from a NIS master to the NIS slave
       server. If a NIS slave server receives a message that there is a new map, it will start ypxfr for
       transfering the new map.  ypxfr will read the contents of a map from the master server using the yp_all()
       function.

       The rpc.ypxfrd server speeds up the transfer process by allowing NIS slave servers to simply copy the
       master servers map files rather than building their own from scratch.  rpc.ypxfrd uses an RPC-based file
       transfer protocol.

       If the on-disk format of the database on both machines is not the same, rpc.ypxfrd will refuse to send
       the data and ypxfr will fallback to yp_all() and fetch every single entry alone.

       rpc.ypxfrd could be started by inetd. But since it starts very slowly, it should be started after ypserv
       from /etc/init.d/ypxfrd.

OPTIONS

       --debug
           Causes the server to run in debugging mode. In debug mode, the server does not background itself and
           prints extra status messages to stderr for each request that it revceives.

       -d path
           rpc.ypxfrd is using this directory instead of /var/yp.

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

       --version
           Prints the version number

SECURITY

       rpc.ypxfrd uses the same functions for checking a host as ypserv. At first, rpc.ypxfrd will check a
       request from an address with /var/yp/securenets or the tcp wrapper. If the host is allowed to connect to
       the server, rpc.ypxfrd will uses the rules from /etc/ypserv.conf to check the requested map. If a mapname
       doesn't match a rule, rpc.ypxfrd will look for the YP_SECURE key in the map. If it exists, rpc.ypxfrd
       will only allow requests on a reserved port.

NOTES

       The FreeBSD ypxfrd protocol is not compatible with that used by SunOS. This is unfortunate but
       unavoidable: SUNs protocol is not freely available, and even if it were it would probably not be useful
       since the SunOS NIS v2 implementation uses the original ndbm package for its map databases whereas the
       other implementation uses GNU DBM or Berkeley DB. These packages uses vastly different file formats.
       Furthermore, ndbm and gdbm are byte-order and word width sensitive and not very smart about it, meaning
       that a gdbm or ndbm database created on a big endian or 64bit system cannot be read on a little endian or
       32bit system. The FreeBSD ypxfrd protocol checks, if both, master and slave, uses the same database
       packages and, if necessary, the byte order of the system.

FILES

       /etc/ypserv.conf
           Configuration file for options and access rights

       /var/yp/securenets
           Configuration file for access rights

SEE ALSO

       ypserv(8), makedbm(8), yppush(8), ypxfr(8)

AUTHOR

       ypxfrd protocol and FreeBSD Implementation: Bill Paul <wpaul@ctr.columbia.edu>

       Linux Implementation: Thorsten Kukuk <kukuk@linux-nis.org>