YPBIND(8) Maintenance Procedures YPBIND(8)
NAME
ypbind - NIS binder process
SYNOPSIS
/usr/lib/netsvc/yp/ypbind [
-broadcast |
-ypset |
-ypsetme]
DESCRIPTION
NIS provides a simple network lookup service consisting of databases and
processes. The databases are stored at the machine that runs an NIS
server process. The programmatic interface to NIS is described in
ypclnt(3NSL). Administrative tools are described in
ypinit(8),
ypwhich(1), and
ypset(8). Tools to see the contents of NIS maps are
described in
ypcat(1), and
ypmatch(1).
ypbind is a daemon process that is activated at system startup time from
the
svc:/network/nis/client:default service. By default, it is invoked as
ypbind -broadcast.
ypbind runs on all client machines that are set up to
use
NIS. The function of
ypbind is to remember information that lets all
NIS client processes on a node communicate with some
NIS server process.
ypbind must run on every machine which has
NIS client processes. The
NIS server 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 association
of a domain name with a
NIS server. The process of binding is driven by
client requests. As a request for an unbound domain comes in, if started
with the
-broadcast option, the
ypbind process broadcasts on the net
trying to find an
NIS server, a
ypserv process serving the domain. Since
the binding is established by broadcasting, there must be at least one
NIS server on the net. If started without the
-broadcast option,
ypbind process steps through the list of
NIS servers that was created by
ypinit -c for the requested domain. There must be an
NIS server process on at
least one of the hosts in the
NIS servers file. It is recommended that
you list each of these NIS servers by name and numeric IP address in
/etc/hosts. Though the practice is not recommended, NIS allows you to
list servers by numeric address only, bypassing
/etc/hosts. In such a
configuration,
ypwhich(1) returns a numeric address instead of a name.
Once a domain is bound by
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
NIS server 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 requested domain is bound. In
general, a bound domain is marked as unbound when the node running the
NIS server crashes or gets overloaded. In such a case,
ypbind will try to
bind to another
NIS server using the process described above.
ypbind also
accepts requests to set its binding for a particular domain. The request
is usually generated by the
ypset(8) command. In order for
ypset to work,
ypbind must have been invoked with flags
-ypset or
-ypsetme.
OPTIONS
-broadcast Send a broadcast datagram using
UDP/IP that requests the information
needed to bind to a specific
NIS server. This option is analogous to
ypbind with no options in earlier Sun releases and is recommended for
ease of use.
-ypset Allow users from any remote machine to change the binding by means of
the
ypset command. By default, no one can change the binding. This
option is insecure.
-ypsetme Only allow
root on the local machine to change the binding to a
desired server by means of the
ypset command.
ypbind can verify the
caller is indeed a
root user by accepting such requests only on the
loopback transport. By default, no external process can change the
binding.
FILES
/var/yp/binding/ypdomain/ypservers
Lists the servers to which the NIS client is allowed to bind.
/etc/inet/hosts File in which it is recommended that NIS servers be listed.
SEE ALSO
svcs(1),
ypcat(1),
ypmatch(1),
ypwhich(1),
ypclnt(3NSL),
hosts(5),
ypfiles(5),
attributes(7),
smf(7),
ifconfig(8),
svcadm(8),
ypinit(8),
ypset(8)NOTES
ypbind supports multiple domains. The
ypbind process can maintain
bindings to several domains and their servers, the default domain is the
one specified by the
domainname(8) command at startup time.
The
-broadcast option works only on the
UDP transport. It is insecure
since it trusts "any" machine on the net that responds to the broadcast
request and poses itself as an
NIS server.
The
ypbind service is managed by the service management facility,
smf(7),
under the service identifier:
svc:/network/nis/client:default
Administrative actions on this service, such as enabling, disabling, or
requesting restart, can be performed using
svcadm(8). The service's
status can be queried using the
svcs(1) command.
May 13, 2017
YPBIND(8)