xref: /freebsd/usr.sbin/ypbind/ypbind.8 (revision 230f8c40e55e3462e90151e30f61bd0fdd4dcda3)
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32.\"	$FreeBSD$
33.\"
34.Dd April 9, 1995
35.Dt YPBIND 8
36.Os
37.Sh NAME
38.Nm ypbind
39.Nd "NIS domain binding daemon"
40.Sh SYNOPSIS
41.Nm ypbind
42.Op Fl ypset
43.Op Fl ypsetme
44.Op Fl s
45.Op Fl S Ar domainname,server1,server2,...
46.Sh DESCRIPTION
47.Nm ypbind
48is the process that maintains NIS binding information. At startup,
49it searches for an NIS server responsible for serving the system's
50default domain (as set by the
51.Xr domainname 1
52command) using network broadcasts.
53Once it receives a reply,
54it will store the address of the server and other
55information in a special file located in
56.Pa /var/yp/binding .
57The NIS routines in the standard C library can then use this file
58when processing NIS requests. There may be several such files
59since it is possible for an NIS client to be bound to more than
60one domain.
61.Pp
62After a binding has been established,
63.Nm ypbind
64will send DOMAIN_NONACK requests to the NIS server at one minute
65intervals. If it fails to receive a reply to one of these requests
66.Nm ypbind
67assumes that the server is no longer running and resumes its network
68broadcasts until another binding is established.
69.Nm ypbind
70will also log warning messages using the syslog(3) facility each time
71it detects that a server has stopped responding, as well as when it
72has bound to a new server.
73.Pp
74.Sh OPTIONS
75The following options are supported by
76.Nm ypbind :
77.Bl -tag -width flag
78.It Fl ypset
79It is possible to force
80.Nm ypbind
81to bind to a particular NIS server host for a given domain by using the
82.Xr ypset 8
83command. However,
84.Nm ypbind
85refuses YPBINDPROC_SETDOM requests by default since it has no way of
86knowing exactly who is sending them. Using the
87.Fl ypset
88flag causes
89.Nm ypbind
90to accept YPBINDPROC_SETDOM requests from any host. This option should only
91be used for diagnostic purposes and only for limited periods since allowing
92arbitrary users to reset the binding of an NIS client poses a severe
93security risk.
94.It Fl ypsetme
95This is similar to the
96.Fl ypset
97flag, except that it only permits YPBINDPROC_SETDOM requests to be processed
98if they originated from the local host.
99.It Fl s
100The
101.Fl s
102flag causes
103.Nm ypbind
104to run in secure mode: it will refuse to bind to any NIS server
105that is not running as root (i.e. that is not using privileged
106TCP ports).
107.It Fl S Ar domainname,server1,server2,server3,...
108The
109.Fl S
110flag allows the system administrator to lock ypbind to a particular
111domain and group of NIS servers. Up to ten servers can be specified.
112There must not be any spaces between the commas in the domain/server
113specification. This option is used to insure that the system binds
114only to one domain and only to one of the specified servers, which
115is useful for systems that are both NIS servers and NIS
116clients: it provides a way to restrict what machines the system can
117bind to without the need for specifying the
118.Fl ypset
119or
120.Fl ypsetme
121options, which are often considered to be security holes. The specified
122servers must have valid entries in the local
123.Pa /etc/hosts
124file. IP addresses may be specified in place of hostnames. If
125.Nm ypbind
126can't make sense ouf of the arguments, it will ignore
127the
128.Fl S
129flag and continue running normally.
130.Pp
131Note that
132.Nm ypbind
133will consider the domainname specified with the
134.Fl S
135flag to be the system default domain.
136.Sh NOTES
137.Nm ypbind
138will not make continuous attempts to keep secondary domains bound.
139If a server for a second dary domain fails to respond to a ping,
140.Nm ypbind
141will broadcast for a new server only once before giving up. If a
142client program attempts to reference the unbound domain, ypbind will
143try broadcasting again. By contrast,
144.Nm ypbind
145will automatically maintain a binding for the default domain whether
146client programs reference it ot not.
147.Sh FILES
148.Bl -tag -width Pa -compact
149.It Pa /var/yp/binding/[domainname].[version]
150The files used to hold binding information for each NIS domain.
151.It Pa /etc/sysconfig
152System configuration file where the system default domain and
153ypbind startup options are specified.
154.El
155.Sh SEE ALSO
156.Xr domainname 1 ,
157.Xr syslog 3 ,
158.Xr yp 4 ,
159.Xr ypserv 8 ,
160.Xr ypset 8
161.Sh AUTHOR
162Theo de Raadt <deraadt@fsa.ca>
163