NIS - Network Information Service
Sun introduced the network information service (NIS), in order to simplify the network administration. Before that, the Yellow Pages service was called, shortened YP. But since this is a trademark of the British Telecom PLC in Great Britain, it was renamed. However, the use of YP in the Tools continued, as ypcat, ypwhich and ypbind. The prefix NIS is used by Sun for NIS+ programs.
NIS makes a simple network information system available consisting of a database and appropriate Daemons. Its purpose is to distribute information, in order that all computers in the entire network are recognized. Information, which is normally distributed by NIS, is for instance:
:rechts: Login Name, passwords and home directory (/etc/passwd)
:rechts: Group information (/etc/group)
:rechts: Computer name and IP number (/etc/hosts)
If a password is registered in the NIS password database now, the owner is in a the position to log himself on any computer which belongs to the same Domain and run the NIS Client programs from there. And the password needs to be changed only once from any client, and not on each one of them.
The use of NIS functions by the libc is seemless for a normal application, i.e. a normal program won't detect NIS running. This determines, which NIS is to be used, which is developed similarly just from the interface like gdbm, ndbm or db-Library interface. The domain name (set and displayed with /bin/domainname)) indicates which domain/group is to be searched. Then the name of the database, also called map, is given and what will be looked for from it. The name of the server is finally known by mean of the daemon ypbind, which must run on each client. ypwhich can display to each user the server used.The C-LIBRARY then sent an appropriate inquiry to the server and gets an answer, which is converted into the format expected by the calling program.
The ypserv process runs on the server, which accepts and executes the requests. Communication runs off thereby over RPC. Ypserv does not have any notion from the structure of the maps and their meaning. It opens the appropriate map in the /var/yp/<domainname directory, and the entry belonging to a key can be returned. This is sent back to the client. Suns ypserv uses ndbm as underlying database library, my Linux version uses gdbm and the BSD variants. Source (in German)∞
There in an entry in Sonya (the #kanotic IRC bot) about NIS:
'nis' could be (#1) apt-get remove --purge nis, or (#2) NIS is a MAJOR SECURITY RISK and should therefore be removed, if ever installed, or (#3) also remove lvm 'apt-get remove --purge lvm2?