The Network Information System (NIS) refers to the service formerly known as Sun Yellow Pages (YP). It is used to make configuration information consistent on all machines in a network. It does this by designating a single host as the master of all the system administration files and databases and distributing this information to all other hosts on the network. The information is compiled into databases called maps. NIS is built on the RPC protocol.
Another version of NIS, NIS+, adds encryption and strong authentication to NIS. NIS+ is a proprietary standard created by Sun Microsystems. This chapter discusses standard NIS, which is supported by most Linux systems. There are currently two NIS servers freely available for Linux, yps and ypserv. We describe ypserv in this book.