Content-type: text/html Man page of ypserv


Section: System Administration Commands (1M)
Updated: 15 Dec 2004
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ypserv, ypxfrd - NIS server and binder processes  


/usr/lib/netsvc/yp/ypserv [-dv] [-i | -I] [-r | -R]



The Network Information Service (NIS) provides a simple network lookup service consisting of databases and processes. The databases are ndbm files in a directory tree rooted at /var/yp. See ndbm(3C). These files are described in ypfiles(4). The processes are /usr/lib/netsvc/yp/ypserv, the NIS database lookup server, and /usr/lib/netsvc/yp/ypbind, the NIS binder. The programmatic interface to the NIS service is described in ypclnt(3NSL). Administrative tools are described in yppoll(1M), yppush(1M), ypset(1M), ypxfr(1M), and ypwhich(1). Tools to see the contents of NIS maps are described in ypcat(1), and ypmatch(1). Database generation and maintenance tools are described in ypinit(1M), ypmake(1M), and makedbm(1M).

The ypserv utility is a daemon process typically activated at system startup from svc:/network/nis/server:default. Alternatively, you can, as the root user, start NIS services using ypstart(1M) from the command-line. ypserv runs only on NIS server machines with a complete NIS database. You can halt all NIS services using the ypstop(1M) command.

The ypxfrd utility transfers entire NIS maps in an efficient manner. For systems that use this daemon, map transfers are 10 to 100 times faster, depending on the map. To use this daemon, be sure ypxfrd is running on the master server. See /usr/lib/netsvc/yp/ypstart. ypxfr attempts to use ypxfrd first. If that fails, it prints a warning, then uses the older transfer method.

The ypserv daemon's primary function is to look up information in its local database of NIS maps.

The operations performed by ypserv are defined for the implementor by the YP Protocol Specification, and for the programmer by the header file <rpcsvc/yp_prot.h>.

Communication to and from ypserv is by means of RPC calls. Lookup functions are described in ypclnt(3NSL), and are supplied as C-callable functions in the libnsl(3LIB) library. There are four lookup functions, all of which are performed on a specified map within some NIS domain: yp_match(3NSL), yp_first(3NSL), yp_next(3NSL), and yp_all(3NSL). The yp_match operation takes a key, and returns the associated value. The yp_first operation returns the first key-value pair from the map, and yp_next can be used to enumerate the remainder. yp_all ships the entire map to the requester as the response to a single RPC request.

A number of special keys in the DBM files can alter the way in which ypserv operates. The keys of interest are:

YP_INTERDOMAIN The presence of this key causes ypserv to forward to a DNS server host lookups that cannot be satisfied by the DBM files.

YP_SECURE This key causes ypserv to answer only questions coming from clients on reserved ports.

YP_MULTI_hostname This is a special key in the form, YP_MULTI_hostname addr1,...,addrN. A client looking for hostname receives the closest address.

Two other functions supply information about the map, rather than map entries: yp_order(3NSL), and yp_master(3NSL). In fact, both order number and master name exist in the map as key-value pairs, but the server will not return either through the normal lookup functions. If you examine the map with makedbm(1M), however, they are visible. Other functions are used within the NIS service subsystem itself, and are not of general interest to NIS clients. These functions include do_you_serve_this_domain?, transfer_map, and reinitialize_internal_state.

On start up, ypserv checks for the existence of the NIS to LDAP (N2L) configuration file /var/yp/NISLDAPmapping. If it is present then a master server starts in N2L mode. If the file is not present it starts in "traditional" (non N2L) mode. Slave servers always start in traditional mode.

In N2L mode, a new set of map files, with an LDAP_ prefix, are generated, based on the contents of the LDAP DIT. The old map files, NIS source files and ypmake(1M) are not used.

It is possible that ypmake(1M) can be accidentally run in N2L mode. If the occurs, the old style map files are overwritten. That the map files are overwritten is harmless. However, any resulting yppush(1M) operation will push information based on the DIT rather than the source files. The user may not expect information based on the DIT. ypserv keeps track of the last modification date of the old style map files. If the map files have been updated, a warning is logged that suggests that the user call yppush directly instead of ypmake.

If a server attempts to run in N2L mode and a LDAP server cannot be contacted, it behaves as follows:

1. When ypserv is started, a warning will be logged.

2. When a NIS read access is made and the TTL entry has expired, a warning is logged.Information that is returned from the cache has not been updated.

3. When a NIS write access is made, a warning is logged. The cache will not be updated, and a NIS failure will be returned.

If ypxfrd is running in N2L mode and is asked to transfer a map, ypxfrd first checks whether the map is out of date. If the map is out of date, ypxfrd initiates an update from the DIT. ypxfrd cannot wait for the update to complete. If ypxfrd waited, the client end ypxfr operation could time out. To prevent ypxfrd from timing out, the existing map is transferred from the cache. The most up to date map will be transferred on subsequent ypxfrd operations.  




-d The NIS service should go to the DNS for more host information. This requires the existence of a correct /etc/resolv.conf file pointing to a DNS server. This option turns on DNS forwarding regardless of whether or not the YP_INTERDOMAIN flag is set in the hosts maps. See makedbm(1M). In the absence of an /etc/resolv.conf file, ypserv complains, but ignores the -d option.

-i If in N2L mode, initialize the NIS related parts of the DIT based on the current, non LDAP_ prefixed, map files. The LDAP_ prefixed maps are not created or updated. If you require that LDAP_ prefixed maps be updated or created, then use the -ir option.

The -i option does not attempt to create any NIS domain or container objects. If any NIS domain or container objects have not already been created, then errors will occur, as entries are written to nonexistent containers.

-I Identical to -i, except that any missing domain and container objects are created.

-r If in N2L mode, then refresh the LDAP_ prefixed map files based on the contents of the DIT.

-ir If both -i and -r are specified in N2L mode, then the DIT will first be initialized from the current non LDAP_ prefixed map files. A new set of LDAP_ prefixed maps will then be generated from the contents of the DIT. A new set of LDAP_ prefixed maps is required when moving from traditional NIS to N2L mode NIS.

-Ir Identical to -ir, except that any missing domain and container objects are created.

-v Operate in the verbose mode, printing diagnostic messages to stderr.

When run with the -i, -r, -I, -ir or -Ir options, the ypserv command runs in the foreground and exits once map initialization has been completed. Once the ypserv command exits, the user knows the maps are ready and can restart ypserv and the other yp daemons by running ypstart(1M).

If there is a requirement to initialize the DIT from the NIS source files, which may have been modified since the maps were last remade, run ypmake before running ypserv -i or ypserv -ir. ypmake regenerated old style NIS maps. Then ypserv -ir dumps them into the DIT. When the -ir option is used, the LDAP_ prefixe maps are also generated or updated. Since these maps will be more recent than the old style maps, ypmake will not be reported as erroneous when it is run.  


/var/yp/securenets Defines the hosts and networks that are granted access to information in the served domain. It is read at startup time by both ypserv and ypxfrd.

/var/yp/ypserv.log If the /var/yp/ypserv.log file exists when ypserv starts up, log information is written to it when error conditions arise.

/var/yp/binding/domainname/ypservers Lists the NIS server hosts that ypbind can bind to.



See attributes(5) for descriptions of the following attributes:




svcs(1), ypcat(1), ypmatch(1), ypwhich(1), domainname(1M), makedbm(1M), svcadm(1M), ypbind(1M), ypinit(1M), ypmake(1M), yppoll(1M), yppush(1M), ypset(1M), ypstart(1M), ypstop(1M), ypxfr(1M), ndbm(3C), ypclnt(3NSL), libnsl(3LIB), NISLDAPmapping(4), securenets(4), ypfiles(4), ypserv(4), attributes(5), smf(5)

Network Interfaces Programmer's Guide

System Administration Guide: Naming and Directory Services (DNS, NIS, and LDAP)  


ypserv supports multiple domains. The ypserv process determines the domains it serves by looking for directories of the same name in the directory /var/yp. It replies to all broadcasts requesting yp service for that domain.

The Network Information Service (NIS) was formerly known as Sun Yellow Pages (YP). The functionality of the two remains the same; only the name has changed. The name Yellow Pages is a registered trademark in the United Kingdom of British Telecommunications PLC, and must not be used without permission.

NIS uses ndbm() files to store maps. Therefore, it is subject to the 1024 byte limitations described in the USAGE and NOTES sections of the ndbm(3C) man page.

The NIS server service is managed by the service management facility, smf(5), under the service identifier:


Administrative actions on this service, such as enabling, disabling, or requesting restart, can be performed using svcadm(1M). The service's status can be queried using the svcs(1) command.




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Time: 02:37:11 GMT, October 02, 2010