ypserv(1M) MISC. REFERENCE MANUAL PAGES ypserv(1M)
NAME
ypserv, ypbind - YP server and binder processes
SYNOPSIS
/usr/lib/netsvc/yp/ypserv /usr/lib/netsvc/yp/ypbind [ -ypset
|-ypsetme ]
DESCRIPTION
The YP provides a simple network lookup service consisting
of databases and processes. The databases are dbm(3) files
in a directory tree rooted at /var/yp. These files are
described in ypfiles(4). The processes are
/usr/sbin/ypserv, the YP database lookup server, and
/usr/sbin/ypbind, the YP binder. The programmatic interface
to YP is described in ypclnt(3N). Administrative tools are
described in yppush(1M), ypxfr(1M), yppoll(1M), ypwhich(1),
and ypset(1M). Tools to see the contents of YP maps are
described in ypcat(1), and ypmatch(1). Database generation
and maintenance tools are described in ypinit(1M),
ypmake(1M), and makedbm(1M). Both ypserv and ypbind are
daemon processes typically activated at system startup time
from /etc/rc.local. ypserv runs only on YP server machines
with a complete YP database. ypbind runs on all machines
using YP services, both YP servers and clients. The ypserv
daemon's primary function is to look up information in its
local database of YP maps. Communication to and from ypserv
is by means of RPC calls. Lookup functions are described in
ypclnt(3N), and are supplied as C-callable functions in the
YP library. There are four lookup functions, all of which
are performed on a specified map within some YP domain:
Match, "Get_first", "Get_next", and "Get_all". The Match
operation takes a key, and returns the associated value.
The "Get_first" operation returns the first key-value pair
from the map, and "Get_next" can be used to enumerate the
remainder. "Get_all" ships the entire map to the requester
as the response to a single RPC request. Two other func-
tions supply information about the map, rather than map
entries: "Get_order_number", and "Get_master_name". 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 will be visible. The func-
tion of ypbind is to remember information that lets client
processes on a single node communicate with some ypserv pro-
cess. ypbind must run on every machine which has YP client
processes; ypserv may or may not be running on the same
node, but must be running somewhere on the network. The
information ypbind remembers is called a binding - the asso-
ciation of a domain name with a YP server. The process of
binding is driven by client requests. As a request for an
unbound domain comes in, the ypbind process steps through
the ypservers list (last entry first) trying to find a
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ypserv(1M) MISC. REFERENCE MANUAL PAGES ypserv(1M)
ypserv process that serves maps within that domain. There
must be a ypserv process on at least one of the hosts in the
ypservers file. Once a domain is bound by a particular
ypbind, that same binding is given to every client process
on the node. The ypbind process on the local node or a
remote node may be queried for the binding of a particular
domain by using the ypwhich(1) command. If ypbind is unable
to speak to 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 the domain once again.
Requests received for an unbound domain will wait until the
domain requested is bound. In general, a bound domain is
marked as unbound when the node running ypserv crashes or
gets overloaded. In such a case, ypbind will to bind
another YP server listed in
/var/yp/binding/domainname/ypservers. ypbind also accepts
requests to set its binding for a particular domain. The
request is usually generated by the YP subsystem itself.
ypset(1M) is a command to access the "Set_domain" facility.
Note: the Set Domain procedure only accepts requests from
processes running as root, ant the -ypset or -ypsetme flags
must have been set for ypbind. The following options are
available for the ypbind command only:
-ypset Allow any user to call ypset(1M). By default,
no one can call ypset(1M).
-ypsetme Only allow root on local machines to call
ypset(1M). By default, no one can call
ypset(1M).
FILES
If the file /var/yp/ypserv.log exists when ypserv starts up,
log information will be written to this file when error con-
ditions arise.
/var/yp
/var/yp/binding/ypdomain/ypservers
SEE ALSO
makedbm(1M), ypcat(1), ypinit(1M), ypmake(1M), ypmatch(1),
yppoll(1M), yppush(1M), ypset(1M), ypwhich(1), ypxfr(1M),
dbm(3X), ypclnt(3N), ypfiles(4)
NOTES
Both ypbind and ypserv support multiple domains. The ypserv
process determines the domains it serves by looking for
directories of the same name in the directory /var/yp.
Additionally, the ypbind process can maintain bindings to
several domains and their servers.
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