ypserv.conf is an ASCII file which contains some options for ypserv. It also contains a list of rules for special host and map access for ypserv and rpc.ypxfrd. This file will be read by ypserv and rpc.ypxfrd at startup, or when receiving a SIGHUP signal.

There is one entry per line. If the line is a option line, the format is:

  • option: <argument>

The line for an access rule has the format:

  • host:domain:map:security

All rules are tried one by one. If no match is found, access to a map is allowed.

Following options exist:

files: 30

This option specifies, how many database files should be cached by ypserv. If 0 is specified, caching is disabled. Decreasing this number is only possible, if ypserv is restarted.

trusted_master: server

When a map is pushed to a slave, the slave normally only accepts updates to existing maps, and then only from the real master. If this option is set on a slave server, new (not yet existing) maps from the host server will be accepted. The default is that no trusted master is set and new maps will not be accepted.



slp: [yes|<no>|domain]

If this option is enabled and SLP support compiled in, the NIS server registers itself on a SLP server. If the variable is set to domain, an attribute domain with a comma seperated list of supported domainnames is set. Else this attribute will not be set.

xfr_check_port: [<yes>|no]

With this option enabled, the NIS master server has to run on a priviliged port (< 1024). The default is "yes" (enabled).

The field descriptions for the access rule lines are:


IP address. Wildcards are allowed.


131.234. =


specifies the domain, for which this rule should be applied. An asterix as wildcard is allowed.


name of the map, or asterisk for all maps.


one of none, port, deny:


always allow access.


allow access if the client request originates from a priviliged port (< 1024). Otherwise do not allow access.


deny access to this map.

You can add /mangle:field to the none or port security keywords. The :field part is optional. It will replace field number field (the default is 2, the password field of the passwd and shadow maps) with the value x for client requests from non-priviliged ports (>= 1024) for the port security keyword and in all cases for the none security keyword.



RELATED TO ypserv.conf…


The access rules for special maps are no real improvement in security, but they make the life a little bit harder for a potential hacker.


Solaris clients don't use privileged ports. All security options that depend on privileged ports cause big problems on Solaris clients.


Thorsten Kukuk <[email protected]>