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YP(8) System Manager's Manual YP(8)

ypdescription of the YP subsystem

ypinit -m [domainname]

ypinit -s master_server [domainname]

ypinit -u [domainname]

ypbind [-insecure] [-ypset] [-ypsetme]

ypset [-d domain] [-h host] server

yppoll [-d domain] [-h host] mapname

ypcat [-kt] [-d domainname] mapname

ypcat -x

ypmatch [-kt] [-d domainname] key ... mapname

ypmatch -x

ypwhich [-t] [-d domain] [[-h] host]

ypwhich [-t] [-d domain] [-h host] -m [mname]

ypwhich -x

ypserv [-1dx] [-a aclfile]

ypxfr [-cf] [-C tid prog ipadd port] [-d domain] [-h host] [-s domain] mapname

yppush [-v] [-d domainname] [-h hostname] mapname

The YP subsystem allows network management of passwd, group, and hosts file entries through the functions getpwent(3), getgrent(3) and gethostbyname(3). A number of other databases can be network-managed as well, and have their respective functions. YP also provides hooks for numerous other client programs such as amd(8) and bootparamd(8) to access distributed and shareable versions of their maps through YP. The YP subsystem requires that portmap(8) be running, since the entire subsystem uses the RPC subsystem.

ypinit is used to initialize YP as a master or a slave. This creates various files in /var/yp. After running ypinit -m, optionally edit /var/yp/DOMAINNAME/Makefile to change settings, for example to switch from the default backwards compatible mode to secure mode. Finally, always run make(1) in /var/yp. See Makefile.yp(8) for details.

If set up as a slave, the required databases are automatically copied from the specified server.

The YP client subsystem is started automatically in /etc/rc if the directory /var/yp/binding exists. The client subsystem can be turned on and off by creating or deleting that directory. ypbind(8) will create that directory if run by hand.

The YP server subsystem is started automatically in /etc/rc if the directory /var/yp/DOMAINNAME exists. This directory is automatically created by ypinit(8) (which initializes the machine as a YP server).

If ypbind cannot find a server, the system behaves the same way as Sun's code does: it hangs.

Top level YP Makefile
YP maps Makefile

domainname(1), ypcat(1), ypmatch(1), ypwhich(1), ypclnt(3), defaultdomain(5), group(5), passwd(5), resolv.conf(5), Makefile.yp(8), portmap(8), ypbind(8), ypinit(8), yppoll(8), yppush(8), ypserv(8), ypset(8), ypxfr(8)

This free YP subsystem is thought to be compatible with Sun's implementation. It is, of course, not compatible with NIS+ or any other “secure” YP subsystem other than the native one.

The name YP stands for Yellow Pee.

The ypbind, most library components, and userland programs were implemented by Theo de Raadt <>. The current getpwent(3) implementation was done by Jason Downs <>. The server component was implemented by Mats O Jansson <>.

November 26, 2015 OpenBSD-6.1