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>