--- name: "ypxfr" section: "8" platform: "freebsd" package: "base" version: "16.0-CURRENT-20261027-61c70dc16a79" release: "FreeBSD 16.0-CURRENT (2026-10-27)" platforms: ["linux", "freebsd", "openbsd"] url: "https://new.carta.tech/ypxfr" --- # ypxfr(8) transfer NIS database from remote server to local host ## NAME **ypxfr** – transfer NIS database from remote server to local host ## SYNOPSIS **/usr/libexec/ypxfr** \[**-f**\] \[**-c**\] \[**-d** *target* *domain*\] \[**-h** *source* *host*\] \[**-s** *source* *domain*\] \[**-p** *path*\] \[**-C** *taskid* *program-number* *ipaddr* *port*\] *mapname* ## DESCRIPTION The **ypxfr** utility copies an NIS database (or *map*) from one NIS server to another using NIS services. In FreeBSD, **ypxfr** is generally invoked by [ypserv(8)](/ypserv/8.md) when it receives a map transfer request from [yppush(8)](/yppush/8.md). The **ypxfr** utility is used primarily in environments where several NIS servers are in use in a single domain. One server, the NIS master, maintains the canonical copies of all NIS maps, and all the other servers, the NIS slaves, copy new versions of the maps from the master whenever any updates are made (i.e., when a user updates their password via [yppasswd(1)](/yppasswd/1.md)). When run, **ypxfr** creates a temporary database file in */var/yp/\[domainname\]*, and fills it with the contents of *mapname* as supplied by the specified *source* *host*. When the entire map has been transferred, **ypxfr** deletes the original copy of *mapname* and moves the temporary copy into its place. When the transfer is complete, **ypxfr** will attempt to send a 'clear current map' request to the local [ypserv(8)](/ypserv/8.md) process to clear any possible references it may still have to the stale map. Note that all files created by **ypxfr** are owner readable and writable only for security reasons. Since the NIS maps and the directory in which they reside are normally owned by root, this prevents non-privileged users from making unauthorized modifications. In order to maintain consistency across all NIS servers, **ypxfr** can be run periodically in a [cron(8)](/cron/8.md) job. Maps which change infrequently need only be updated once a day (preferably late at night when system usage is lowest), whereas those that are subject to frequent changes (such a *passwd.byname* and *passwd.byuid*) should be updated perhaps once every hour. Using [cron(8)](/cron/8.md) to automatically update the NIS maps is not strictly mandatory since all updates should be propagated by [yppush(8)](/yppush/8.md) when */var/yp/Makefile* is run on the NIS master server, however it is good practice on large networks where possible outages could cause NIS servers to fall out of sync with each other. When **ypxfr** is invoked without a controlling terminal, e.g. from inside [ypserv(8)](/ypserv/8.md), it logs all its output using the [syslog(3)](/syslog/3.md) facility. ## NOTES The FreeBSD version of **ypxfr** has support for a special map transfer protocol which works in conjunction with the FreeBSD [rpc.ypxfrd(8)](/rpc.ypxfrd/8.md) server. This protocol allows it to transfer raw map database files from the NIS master server and can be many times faster than the standard transfer method, particularly for very large NIS maps. The **ypxfr** utility will check to see if the [rpc.ypxfrd(8)](/rpc.ypxfrd/8.md) server is registered on the NIS master server and attempt to use it if it is present. If it is not it will fall back to the standard transfer method, copying the map contents from [ypserv(8)](/ypserv/8.md) and creating new maps instead. Note that while the FreeBSD ypxfrd protocol is conceptually similar to the SunOS ypxfrd protocol, the FreeBSD protocol is not compatible with Sun's, therefore it will not work with Sun's ypxfrd server. FreeBSD slave systems can still transfer maps from any non-FreeBSD NIS server, however they will only be able to take advantage of the faster protocol if the master server is also running FreeBSD. ## OPTIONS The following options and flags are supported by **ypxfr**: - **-f** Force a map transfer. Normally, **ypxfr** will not transfer a map if it determines that the NIS master's copy is not newer than the existing copy already on the local host: the **-f** flag forces a transfer regardless of which server's version is more recent. - **-c** Do not send a 'clear current map' request to the [ypserv(8)](/ypserv/8.md) process running on the local host. This flag is normally used when invoking **ypxfr** manually on a machine that is not yet running [ypserv(8)](/ypserv/8.md). Without this flag, failure to contact the local NIS server will cause **ypxfr** to abort the transfer. - **-d** *target* *domain* Specify a target domain other than the current NIS domain. - **-h** *source* *host* Specify the name of the host from which to copy the NIS maps. This option is used to ensure that **ypxfr** only copies maps from the NIS master server. - **-s** *source* *domain* Specify the domain from which to transfer a map, in the event that the transfer is being done across two different NIS domains. - **-p** *path* Specify the top level directory containing the NIS maps. By default, this path is */var/yp*. The **-p** flag allows you to specify an alternate path should you wish to store your NIS maps in a different part of the file system. The NIS server, [ypserv(8)](/ypserv/8.md), passes this flag to **ypxfr** if it too has been told to use an alternate path. - **-C** *taskid* *program-number* *ipaddr* *port* These options are used only when **ypxfr** is invoked by [ypserv(8)](/ypserv/8.md) in response to a map transfer request initiated by [yppush(8)](/yppush/8.md). In this instance, **ypxfr** needs to 'callback' to the [yppush(8)](/yppush/8.md) process and interact with it, so [yppush(8)](/yppush/8.md) passes to it an IP address *ipaddr*, port number *port*, registered program number *program-number* and a transaction ID *taskid* that it can use to contact the waiting [yppush(8)](/yppush/8.md) process on the master server. - *mapname* The name of the map to transfer. ## FILES - */var/yp/\[domainname\]/\[maps\]* The NIS maps for a particular NIS domain. ## SEE ALSO [yp(8)](/yp/8.md), [yppush(8)](/yppush/8.md), [ypserv(8)](/ypserv/8.md) ## AUTHORS Bill Paul ⟨*wpaul@ctr.columbia.edu*⟩