The maps themselves are usually generated from master (Florida web design)
The maps themselves are usually generated from master text files such as /etc/hosts or /etc/passwd. For some files, several maps are created, one for each search key type. For instance, you may search the hosts file for a hostname as well as for an IP address. Accordingly, two NIS maps are derived from it, called hosts.byname and hosts.byaddr. Table 13.1 lists common maps and the files from which they are generated. Table 13.1: Some Standard NIS Maps and Corresponding Files Master File Map(s) Description /etc/hosts hosts.byname, hosts.byaddr Maps IP addresses to host names /etc/networks networks.byname, networks.byaddr Maps IP network addresses to network names /etc/passwd passwd.byname, passwd.byuid Maps encrypted passwords to user login names /etc/group group.byname, group.bygid Maps Group IDs to group names /etc/services services.byname, services.bynumber Maps service descriptions to service names /etc/rpc rpc.byname, rpc.bynumber Maps Sun RPC service numbers to RPC service names /etc/protocols protocols.byname, protocols. bynumber Maps protocol numbers to protocol names /usr/lib/aliases mail.aliases Maps mail aliases to mail alias names You may find support for other files and maps in other NIS packages. These usually contain information for applications not discussed in this book, such as the bootparams map that is used by Sun’s bootparamd server. For some maps, people commonly use nicknames, which are shorter and therefore easier to type. Note that these nicknames are understood only by ypcat and ypmatch, two tools for checking your NIS configuration. To obtain a full list of nicknames understood by these tools, run the following command: $ ypcat -x Use “passwd” for “passwd.byname” Use “group” for “group.byname” Use “networks” for “networks.byaddr” Use “hosts” for “hosts.byaddr” Use “protocols” for “protocols.bynumber” Use “services” for “services.byname” Use “aliases” for “mail.aliases” Use “ethers” for “ethers.byname” The NIS server program is traditionally called ypserv. For an average network, a single server usually suffices; large networks may choose to run several of these on different machines and different segments of the network to relieve the load on the server machines and routers. These servers are synchronized by making one of them the master server, and the others slave servers. Maps are created only on the master server’s host. From there, they are distributed to all slaves. We have been talking very vaguely about “networks.” There’s a distinctive term in NIS that refers to a collection of all hosts that share part of their system configuration data through NIS: the NIS domain. Unfortunately, NIS domains have absolutely nothing in common with the domains we encountered in DNS. To avoid any ambiguity throughout this chapter, we will therefore always specify which type of domain we mean.