Learn about NIS server(Network Information System)
is a network naming and administration system for smaller networks that was developed by Sun Microsystems.
uses the client/server model and the Remote Procedure Call (RPC) interface for communication between hosts. NIS
consists of a server, a library of client programs, and some administrative tools. NIS
is often used with the Network File System (NFS). NIS
is a Unix-based program.
It is more efficient to combine machines into groups that share configuration information. This can be done in various ways.
The most commonly shared files are:
/etc/passwd - User account information
/etc/group - UNIX group definitions
/etc/hosts - Maps hostnames and ip addresses
/etc/services - Lists port numbers for well-known network services
/etc/protocols - Maps text names to protocol numbers
/etc/ethers* - Maps hostnames and ethernet addresses
/etc/aliases - Mail alias definitions, including postmaster
/etc/rpc - Lists id numbers for rpc services
/etc/netgroup - Defines collections of hosts, users and networks
Advantages / Disadvantages of NIS
is fairly easy to maintain without being aware of the internal data formats, you just edit the same "flat" files, and learn one or two new procedures to go with it.
is a very good way to easily maintain a large number of users and groups across a large number of shared systems. These systems have to be configured similarly.
can consume a lot of network bandwidth since NIS
doesn't cache data on client machines. Every lookup causes an exchange of network packets. When a master's maps get updated, every slave server is also updated with the new maps. So it's a tradeoff depending on your setup.
is not secure! Outside hosts can pose as a client of your domain and grab your maps. Once they get your password map, a crack program can be run on it to decrypt passwords, opening your system up. For this reason it is fairly important to pick an obscure domain name, and not something like "cmsc" for say the computer science domain.
NIS commands and daemons
: NIS server
daemon started at boot time by master/slave servers
client daemon started at boot time by all
: Downloads current version of a map from master server
: Serves requests from ypxfr (runs on master)
: Makes slave servers update their map versions
: Builds a ndbm map from a flat file
: Rebuilds ndbm maps from flat files that have changed (IRIX)
: Configures a host as a master or slave server
: Makes ypbind connect to a particular server
: Finds out which server the current host is using
: Finds out what version of a map a server is using
: Prints the values contained in an NIS
: Prints map entries for a specified key
: Changes a password on the NIS
: Changes GECOS info on the NIS
: Changes a login shell on NIS
: Server for yppasswd, ypchsh and ypchfn
: Server for updating NIS
maps (managed by inetd)