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)