YPBIND(8) Maintenance Commands and 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)