rpc.ypxfrd(8) NIS map transfer server


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


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. This process can take several minutes when there are very large maps which have to be stored by the database library.

The rpc.ypxfrd server speeds up the transfer process by allowing NIS slave servers to simply copy the master server's map files rather than building their own from scratch. rpc.ypxfrd uses an RPC-based file transfer protocol, so that there is no need for building a new map.

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


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 directory
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.
Prints the version number


rpc.ypxfrd uses the same functions for checking a host as ypserv. At first, rpc.ypxfrd will check a request from an address with /etc/ypserv.securenets. 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.


/etc/ypserv.conf /var/yp/securenets


The FreeBSD ypxfrd protocol is not compatible with that used by SunOS. This is unfortunate but unavoidable: Sun's protocol is not freely available, and even if it were it would probably not be useful since the SunOS NIS v2 implimentation uses the original ndbm package for its map databases whereas the other implimentation uses GNU DBM or Berkeley DB. These packages uses vastly different file formats. Furthermore, ndbm and gdbm are byte-order sensitive and not very smart about it, meaning that a gdbm or ndbm database created on a big endian system can't be read on a little endian 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.


ypxfrd protocol and FreeBSD Implementation: Bill Paul <[email protected]>
Linux Implementation: Thorsten Kukuk <[email protected]>