ypbind
finds the server for NIS domains and maintains the NIS binding
information. The client (normaly the NIS routines in the standard C library)
could get the information over RPC from
ypbind
or read the binding files. The binding files resides in the directory
/var/yp/binding
and are conventionally named
[domainname].[version].
The supported versions are 1 and 2.
There could be several such files since it is possible for an NIS client
to be bound to more then one domain.
After a binding has been established,
ypbind
will send YPPROC_DOMAIN requests to the current NIS server at 20 seconds
intervals. If it doesn't get an response or the NIS server reports that he
doesn't have this domain any longer,
ypbind
will search for a new NIS server. All 15 minutes
ypbind
will check to see if the current NIS server is the fastest. If it find
a server which answers faster, it will switch to this server.
You could tell
ypbind
to use network broadcasts to find a new server, what is insecure,
or you could give it a list of known secure servers.
In this case
ypbind
will send a ping to all servers and binds to first one which answers.
Unless the option
-debug
is used, ypbind detaches itself from the controlling terminal and puts
itself into background.
ypbind
uses
syslog(3)
for logging errors and warnings.
At startup or when receiving signal SIGHUP,
ypbind
parses the file
/etc/yp.conf
and tries to use the entries for its initial binding. Valid entries
are
domainnisdomainserverhostname
Use server
hostname
for the domain
nisdomain.
You could have more then one entry of this type for a single domain.
domainnisdomainbroadcast
Use broadcast on the local net for domain
nisdomain.
ypserverhostname
Use server
server
for the local domain.
A broadcast entry in the configuration file will overwrite a ypserver/server
entry and a ypserver/server entry broadcast. If all given server are down,
ypbind
will
not
switch to use broadcast.
ypbind
will try at first
/etc/hosts
and then
DNS
for resolving the hosts names from
/etc/yp.conf.
If
ypbind
couldn't reconfigure the search order, it will use only
DNS.
If
DNS
isn't available, you could only use IP-addresses in
/etc/hosts.
ypbind
could only reconfigure the search order with glibc 2.x.
If the
-broadcast
option is specified,
ypbind
will ignore the configuration file.
If the file does not exist or if there are no valid entries,
ypbind
exit.
This
ypbind
is a special version which uses
pthreads.
It will start 2 more threads. The master process services RPC requests
asking for binding info. The first thread initializes the binding and
checks it periodically. Upon failure, the binding is invalidated and
the process tries again to find a valid server. The second thread
will handle all the signals.
OPTIONS
-broadcast
Send a broadcast to request the information needed to bind to a
specific NIS server. With this option,
/etc/yp.conf
will be ignored.
-ypset
Allow
root
from any remote machine to change the binding for a domain via the
ypset(8)
command. By default, no one can change the binding. This option is really
insecure. If you change a binding for a domain, all the current known
servers for this domain will be forgotten. If the new server goes down,
ypbind
will use the old searchlist.
-ypsetme
The same as
-ypset,
but only
root
on the local machine is allowed to chang the binding. Such requests
are only allowd from
loopback.
-c
ypbind
only checks if the config file has syntax errors and exits.
-debug
starts
ypbind
in debug mode.
ypbind
will not put itself into background, and error messages and debug
output are written to standard error.
-verbose
Causes
ypbind
to syslog(2) any and all changes in the server its bound to.
-broken-server
lets
ypbind
accept answers from servers running on an illegal port number. This should
usually be avoided, but is required by some
ypserv(8)
versions.
-no-ping
ypbind
will not check if the binding is alive. This option is for use with
dialup connections to prevent
ypbind
from keeping the connection unnessecarily open or causing autodials.
-f configfile
ypbind
will use
configfile
and not
/etc/yp.conf
-local-only
ypbind
will only bind to the loopback device and is not reacheable from
a remote network.
-ping-interval ping-interval
The default value for
ypbind
to check, if a NIS server is still reacheable, is 20 seconds.
With this options another frequency in seconds can be specified.
--version
Prints the version number
NOTES
Binding to multiple domains is tested and works.
Load sharing between multiple servers for a single domain is
not supported.
ypbind
will always try to bind a domain to a server. If there is no valid
server in the list or answers to a broadcast, the domain is unbounded.
FILES
/etc/yp.conf
configuration file.
/var/yp/binding/[domainname].[version]
binding file containing information about each NIS domain.
/var/run/ypbind.pid
contains the process id of the currently running
ypbind
master process.
