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

ypbindcreate and maintain a binding to a YP server

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

ypbind finds the server for a particular YP domain and stores information about it in a “binding file”. This binding information includes the IP address of the server associated with that particular domain and which port the server is using. This information is stored in the directory /var/yp/binding in a file named with the convention DOMAINNAME.version. (The YP system only supplies information on version 2.)

When ypbind starts the primary domain (or gets the first request for a new domain), it checks if a file for the domain in question exists in the directory /etc/yp/ (i.e., /etc/yp/DOMAINNAME). If such a file exists, it will list the hosts which ypbind should restrict its server search to. Otherwise, ypbind assumes it will need to use broadcasts to find a valid server. Using either of these techniques, ypbind will search for a server willing to serve maps for the client's domain. Once a binding is established, ypbind maintains this binding by periodically communicating with the server to which it is bound. If the binding is somehow lost, e.g by server reboot, ypbind marks the domain as unbound and attempts to re-establish the binding. When the binding is once again successful, ypbind marks the domain as bound and resumes its periodic check.

The options are as follows:

Permit binding to a ypserv(8) on a non-reserved port. This is needed if receiving maps from SunOS 3.x or Ultrix.
ypset(8) may be used to change the server to which a domain is bound.
ypset(8) may be used only from this machine to change the server to which a domain is bound.

The -ypset and -ypsetme options are dangerous and should be avoided. For greatest security, the use of a server list in /etc/yp/DOMAINNAME is recommended. The file should contain a list of valid YP server hostnames, with one hostname per line. The comment character is #.

/var/yp/binding/DOMAINNAME.version - binding file for domainname /etc/yp/DOMAINNAME - server list for this particular domain

domainname(1), ypcat(1), ypmatch(1), ypwhich(1), yp(8), yppoll(8), ypserv(8), ypset(8)

Once ypbind is running, the following pages should be reviewed in order to see how to enable YP support for each of the following maps: ethers(5), group(5), hosts(5), networks(5), passwd(5), resolv.conf(5)

Theo de Raadt

February 17, 2017 OpenBSD-6.3