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Network Information Service

lastmod 2020-11-20created 2020-11-202 edits

Network Information Service (NIS) is a client-server directory service protocol from Sun Microsystems that distributes system configuration data, such as user and host names, between computers on a computer network.

Sun licenses this technology to virtually every Unix vendor.

NIS commands

  • ypcat - Prints the values in an NIS map.
  • ypmatch - Prints the values for specific keys in an NIS map.
  • ypwhich - Finds out which server the current host is using.
  • ypclnt - A suite of programmer's routines that provides an interface to the YP subsystem.
  • yppasswd - Changes the password in an NIS domain.
  • ypset - Binds ypbind to a specific server.
  • ypmake - Builds new hash maps from changed files.
  • ypinit - Configures a host as a master or slave server.
  • yppush - Updates slave servers with its own version of the maps.

NIS daemons

  • ypserv - NIS server daemon
  • ypxfrd - NIS server daemon, transfers maps to slave servers
  • ypbind - Runs on all NIS systems. Makes NIS requests from clients to ypserv on the NIS server.
  • rpc.yppasswd - ord map
  • rpc.ypupdated - Runs only on the NIS master. Updates the public key maps when secure "remote procedure call" is in use.

Security risks

Network Information Service (NetWork Information service, formerly YP) is one way of distributing information to a group of computers. The NIS master server owns the information tables and converts them into NIS map files. These map files are served over the network, allowing NIS client computers to obtain login and password, home directory, and shell information (that is, all the information in a typical /etc/passwd file). With NIS, users can change their password once and have it (updated) on every computer in that NIS domain. NIS is not secure. It was never designed with security in mind. It was made only to be convenient and useful for the job. Anyone (anywhere on the network) who can guess the name of your NIS domain can get a copy of your passwd file and use "Crack" and "John the ripper" to crack your users' passwords. NIS can also be spoofed into doing all sorts of nasty things. If you must use NIS, you have to accept these risks.

See also

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