NAME
ypserv - NIS server
SYNOPSIS
/usr/sbin/ypserv
[
-d
[
path
] ]
[
-p port
]
DESCRIPTION
The
Network Information Service (NIS)
provides a simple network lookup service
consisting of databases and processes. The databases are
gdbm
files in a directory tree rooted at
R /var/yp .
The
ypserv
daemon is typically activated at system startup.
ypserv
runs only on
NIS
server machines with a complete
NIS
database. On other machines using the
NIS
services, you have to run
ypbind
as client or under Linux you could use the libc with
NYS
support.
ypbind
must run on every machine which has
NIS
client processes;
ypserv
may or may not be running on the same node,
but must be running somewhere
on the network. On startup or when receiving the signal SIGHUP,
ypserv
parses the file
/etc/ypserv.conf.
OPTIONS
-d --debug [path]
Causes the server to run in debugging mode. Normally,
ypserv
reports only errors (access violations, dbm failures)
using the syslog(3) facility. In debug mode, the server does not
background itself and prints extra status messages to stderr for
each request that it revceives.
path
is an optionally parameter.
ypserv
is using this directory instead of /var/yp
-p --port port
ypserv
will bind itself to this port.
This makes it possible to have a router filter packets
to the NIS ports, so that access to the NIS server from
hosts on the Internet can be restricted.
-v --version
Prints the version number
SECURITY
In general, any remote user can issue an RPC to
ypserv
and retrieve the contents of your NIS maps, if he knows your
domain name. To prevent such unauthorized transactions,
ypserv
supports a feature called
securenets
which can be used to restrict access to a given set of hosts.
At startup or when arriving the SIGHUP Signal,
ypserv
will attempt to load the securenets information from a file
called
/etc/ypserv.securenets .
This file contains entries that consist of a netmask
and a network pair separated by white spaces.
Lines starting with ``#'' are considered to be comments.
A sample securenets file might look like this:
# allow connections from local host -- necessary
host 127.0.0.1
# same as 255.255.255.255 127.0.0.1
#
# allow connections from any host
# on the 131.234.223.0 network
255.255.255.0 131.234.223.0
# allow connections from any host
# between 131.234.214.0 and 131.234.215.255
255.255.254.0 131.234.214.0
If
ypserv
receives a request from an address that fails to match a rule,
the request will be ignored and a warning message will be
logged. If the
/etc/ypserv.securenets
file does not exist,
ypserv
will allow connections from any host.
In the
/etc/ypserv.conf
you could specify some access rules for special maps and hosts. But
it is not very secure, it makes the life only a little bit harder
for a potential hacker. If a mapname doesn't match a rule, ypserv will
look for the YP_SECURE key in the map. If it exists, ypserv will
only allow requests on a reserved port.
For security reasons, ypserv will only accept ypproc_xfr requests for
updating maps from the same master server as the old one. This means,
you have to reinstall the slave servers if you change the master server
for a map.
FILES
/etc/ypserv.conf
/etc/ypserv.securenets
SEE ALSO
domainname(1),
ypcat(1),
ypmatch(1),
ypserv.conf(5),
netgroup(5),
makedbm(8),
revnetgroup(8),
ypinit(8),
yppoll(8),
yppush(8),
ypset(8),
ypwhich(8),
ypxfr(8),
rpc.ypxfrd(8)
The Network Information Service
(\s-1NIS\s0)
was formerly known as Sun Yellow Pages
(\s-1YP\s0).
The functionality of the two remains the same;
only the name has changed.
The name Yellow Pages is a registered trademark in the United Kingdom
of British Telecommunications plc,
and may not be used without permission.
AUTHOR
ypserv
was written by Peter Eriksson <pen@lysator.liu.se>.
Thorsten Kukuk <kukuk@suse.de> added support for master/slave
server and is the new Maintainer.
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