ypserv(1M)

NAME

ypserv, ypbind − Network Information Service server and binder processes

SYNOPSIS

/usr/etc/ypserv [-l log_file]
/etc/ypbind [-l log_file] [-ypset]

DESCRIPTION

The Network Information Service (NIS) provides a simple network lookup service consisting of databases and processes. The databases are files in a directory tree rooted at /usr/etc/yp (see ypfiles(4)). The processes are /usr/etc/ypserv, the NIS database lookup server, and /etc/ypbind, the NIS binder. Both ypserv and ypbind are daemon processes typically activated at system startup time from within /etc/netnfsrc.

The NIS programmatic interface is described in ypclnt(3C). Administrative tools are described in ypwhich(1), yppoll(1M), yppush(1M), ypset(1M) and ypxfr(1M). Tools to see the contents of NIS maps (databases) are described in ypcat(1) and ypmatch(1). Database generation and maintenance tools are described in makedbm(1M), ypinit(1M), and ypmake(1M). The command to set or show the default NIS domain is domainname(1).

The ypserv daemon’s primary function is to look up information in its local collection of NIS maps. It runs only on NIS server machines providing data from NIS databases. Communication to and from ypserv is by means of RPC. Lookup functions are described in ypclnt(3C) and are supplied as C-callable functions in /lib/libc.a.

Four lookup functions perform on a specific map within a NIS domain: Match, Get_first, Get_next, and Get_all. The Match operation matches a key to a record in the database and returns its associated value. The Get_first operation returns the first key-value pair (record) from the map, and Get_next enumerates (sequentially retrieves) the remainder of the records. Get_all returns all records in the map to the requester as the response to a single RPC request.

Two other functions supply information about the map other than normal map entries: Get_order_number and Get_master_name. The order number is the time of last modification of a map. The master name is the host name of the machine on which the master map is stored. Both order number and master name exist in the map as special key-value pairs, but the server does not return these through the normal lookup functions (if you examine the map with makedbm or yppoll − see makedbm(1M) or yppoll(1M); − however, they will be visible). Other functions are used within the NIS system and are not of general interest to NIS clients. They include Do_you_serve_this_domain?, Transfer_map, and Reinitialize_internal_state.

The ypbind daemon remembers information that lets client processes on its machine communicate with a ypserv process. The ypbind daemon must run on every machine using NIS services, both NIS servers and clients. The ypserv daemon may or may not be running on a NIS client machine, but it must be running somewhere on the network or be available through a gateway.

The information ypbind remembers is called a binding: the association of a NIS domain name with the internet address of the NIS server and the port on that host at which the ypserv process is listening for service requests. Client requests drive the binding process. As a request for an unbound domain comes in, the ypbind process broadcasts on the network trying to find a ypserv process serving maps within that NIS domain. Since the binding is established by broadcasting, at least one ypserv process must exist on every network. Once a binding is established for a client, it is given to subsequent client requests. Execute ypwhich to query the ypbind process (local and remote) for its current binding (see ypwhich(1)).

Bindings are verified before they are given to a client process. If ypbind is unable to transact with the ypserv process it is bound to, it marks the domain as unbound, tells the client process that the domain is unbound, and tries to bind again. Requests received for an unbound domain fail immediately. Generally, a bound domain is marked as unbound when the node running ypserv crashes or is overloaded. In such a case, ypbind binds to any NIS server (typically one that is less heavily loaded) available on the network.

The ypbind daemon also accepts requests to set its binding for a particular domain. ypset accesses the Set_domain facility; it is for unsnarling messes and is not for casual use.

Options

ypserv recognizes the following options:

-l log_file Log diagnostic and error messages to the specified log_file. The ypserv daemon writes its messages to /usr/etc/yp/ypserv.log if ypserv is started without the -l (ell) option and the file exists. The ypbind daemon writes its messages directly to the system console, /dev/console, if ypbind is started without the -l (ell) option.

-ypset Allow ypset to be used to change the binding (see ypset(1M)). For maximum security this option should be used only when debugging the network from a remote machine.

Information logged to the file includes date and time of the message, the host name, process id and name of the function generating the message, and the message itself. Note that different services can share a single log file since enough information is included to uniquely identify each message.

AUTHOR

ypserv was developed by Sun Microsystems, Inc.

FILES

/usr/etc/yp/ypserv.log default ypserv error log file

INTERNATIONAL SUPPORT

messages

Hewlett-Packard Company — HP-UX Release 9.10: April 1995

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