YPBIND(8) BSD System Manager's Manual YPBIND(8)NAMEypbind - NIS domain binding daemon
SYNOPSISypbind [-ypset] [-ypsetme] [-s] [-S domainname,server1,server2,...]
DESCRIPTIONypbind is the process that maintains NIS binding information. At startup,
it searches for an NIS server responsible for serving the system's de-
fault domain (as set by the domainname(1) command) using network broad-
casts. Once it receives a reply, it will store the address of the server
and other information in a special file located in /var/yp/binding. The
NIS routines in the standard C library can then use this file when pro-
cessing NIS requests. There may be several such files since it is possi-
ble for an NIS client to be bound to more than one domain.
After a binding has been established, ypbind will send DOMAIN_NONACK re-
quests to the NIS server at one minute intervals. If it fails to receive
a reply to one of these requests ypbind assumes that the server is no
longer running and resumes its network broadcasts until another binding
is established. ypbind will also log warning messages using the sys-
log(3) facility each time it detects that a server has stopped respond-
ing, as well as when it has bound to a new server.
OPTIONS
The following options are supported by ypbind:
-ypset
It is possible to force ypbind to bind to a particular NIS server
host for a given domain by using the ypset(8) command. However,
ypbind refuses YPBINDPROC_SETDOM requests by default since it has
no way of knowing exactly who is sending them. Using the -ypset
flag causes ypbind to accept YPBINDPROC_SETDOM requests from any
host. This option should only be used for diagnostic purposes and
only for limited periods since allowing arbitrary users to reset
the binding of an NIS client poses a severe security risk.
-ypsetme
This is similar to the -ypset flag, except that it only permits YP-
BINDPROC_SETDOM requests to be processed if they originated from
the local host.
-s The -s flag causes ypbind to run in secure mode: it will refuse to
bind to any NIS server that is not running as root (i.e. that is
not using privileged TCP ports).
-S domainname,server1,server2,server3,...
The -S flag allows the system administrator to lock ypbind to a
particular domain and group of NIS servers. Up to ten servers can
be specified. There must not be any spaces between the commas in
the domain/server specification. This option is used to insure that
that the system binds only to one domain and only to one of the
specified servers, which is useful for systems that are both NIS
servers and NIS clients: it provides a way to restrict what ma-
chines the system can bind to without the need for specifying the
-ypset or -ypsetme options, which are often considered to be secu-
rity holes. The specified servers must have valid entries in the
local /etc/hosts file. IP addresses may be specified in place of
hostnames. If ypbind can't make sense out of the arguments, it will
ignore the -S flag and continue running normally.
Note that ypbind will consider the domainname specified with the -S
flag to be the system default domain.
NOTESypbind will not make continuous attempts to keep secondary domains bound.
If a server for a second dary domain fails to respond to a ping, ypbind
will broadcast for a new server only once before giving up. If a client
program attempts to reference the unbound domain, ypbind will try broad-
casting again. By contrast, ypbind will automatically maintain a binding
for the default domain whether client programs reference it ot not.
FILES
/var/yp/binding/[domainname].[version]
The files used to hold binding information for each NIS domain.
/etc/sysconfig
System configuration file where the system default domain and yp-
bind startup options are specified.
SEE ALSOdomainname(1), ypset(8)AUTHOR
Theo de Raadt <deraadt@fsa.ca>
BSDI BSD/OS April 9, 1995 2
