Книга: Linux Network Administrator Guide, Second Edition

Running an NIS Server

Running an NIS Server

After so much theoretical techno-babble, it's time to get our hands dirty with actual configuration work. In this section, we will cover the configuration of an NIS server. If an NIS server is running on your network, you won't have to set up your own; in this case, you may safely skip this section.

Note that if you are just going to experiment with the server, make sure you don't set it up for an NIS domain name that is already in use on your network. This may disrupt the entire network service and make a lot of people very unhappy and very angry.

There are two possible NIS server configurations: master and slave. The slave configuration provides a live backup machine, should your master server fail. We will cover the configuration only for a master server here. The server documentation will explain the differences, should you wish to configure a slave server.

There are currently two NIS servers freely available for Linux: one contained in Tobias Reber's yps package, and the other in Peter Eriksson's ypserv package. It doesn't matter which one you run.

After installing the server program (ypserv) in /usr/sbin, you should create the directory that is going to hold the map files your server is to distribute. When setting up an NIS domain for the brewery domain, the maps would go to /var/yp/brewery. The server determines whether it is serving a particular NIS domain by checking if the map directory is present. If you are disabling service for some NIS domain, make sure to remove the directory as well.

Maps are usually stored in DBM files to speed up lookups. They are created from the master files using a program called makedbm (for Tobias's server) or dbmload (for Peter's server).

Transforming a master file into a form that dbmload can parse usually requires some awk or sed magic, which tends to be a little tedious to type and hard to remember. Therefore, Peter Eriksson's ypserv package contains a Makefile (called ypMakefile) that manages the conversion of the most common master files for you. You should install it as Makefile in your map directory and edit it to reflect the maps you want the NIS server to share. Towards the top of the file, you'll find the all target that lists the services ypserv offers. By default, the line looks something like this:

all: ethers hosts networks protocols rpc services passwd group netid

If you don't want to produce, for example, the ethers.byname and ethers.byaddr maps, simply remove the ethers prerequisite from this rule. To test your setup, you can start with just one or two maps, like the services.* maps.

After editing the Makefile, while in the map directory, type make. This will automatically generate and install the maps. You have to make sure to update the maps whenever you change the master files, otherwise the changes will remain invisible to the network.

The section "Setting Up an NIS Client with GNU libc" will explain how to configure the NIS client code. If your setup doesn't work, you should try to find out whether requests are arriving at your server. If you specify the -debug command-line flag to ypserv, it prints debugging messages to the console about all incoming NIS queries and the results returned. These should give you a hint as to where the problem lies. Tobias's server doesn't have this option.

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