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.Dd June 14, 2014
.Dt YPBIND 8
.Os
.Sh NAME
.Nm ypbind
.Nd create and maintain a binding to a NIS server
.Sh SYNOPSIS
.Nm
.Op Fl broadcast
.Op Fl insecure
.Op Fl ypset
.Op Fl ypsetme
.Sh DESCRIPTION
.Nm
finds the server for a particular
.Tn NIS
domain and stores information about it
in a
.Dq binding file .
This binding information includes the IP address of the server associated with
that particular domain and which port the server is using.
This information is stored in the directory
.Pa /var/yp/binding
in a file named with the convention
.Pa <domain>.version ,
where
.Aq domain
is the relevant domain.
The
.Tn NIS
system only supplies information on version 2.
.Pp
If
.Nm
is started without the
.Fl broadcast
option,
.Nm
steps through the list of
.Tn NIS
servers specified in
.Pa /var/yp/binding/<domain>.ypservers
and contacts each in turn attempting to bind to that server.
It is strongly recommended that these hosts are in the local
hosts file, and that hosts are looked up in local files before
the
.Tn NIS
hosts map.
.Pp
If
.Nm
is started with the
.Fl broadcast
option, or if
.Pa /var/yp/binding/<domain>.ypservers
does not exist,
.Nm
broadcasts to find a process willing to serve maps for the
client's domain.
.Pp
Once a binding is established,
.Nm
maintains this binding by periodically communicating with the server to which
it is bound.
If the binding is somehow lost, e.g by server reboot,
.Nm
marks the domain as unbound and attempts to re-establish the binding.
If a binding cannot be re-established within 60 seconds,
.Nm
backs off exponentially to trying only once per hour.
.Pp
The options are as follows:
.Bl -tag -width "-broadcast"
.It Fl broadcast
sends a broadcast requesting a
.Tn NIS
server to which to bind.
.It Fl insecure
do not require that the server is running on a reserved port.
This may be necessary when connecting to
.Tn SunOS 3.x
or
.Tn ULTRIX
.Tn NIS
servers.
.It Fl ypset
.Xr ypset 8
may be used from anywhere to change the server to which a domain is bound.
.It Fl ypsetme
.Xr ypset 8
may be used only from this machine to change the server
to which a domain is bound.
.El
.Pp
The
.Fl broadcast ,
.Fl ypset ,
and
.Fl ypsetme
options are inherently insecure and should be avoided.
.Sh SIGNALS
.Nm
responds to the following signals:
.Bl -tag -width TERM -compact
.It Dv HUP
causes
.Nm
to immediately retry any unbound domains that are currently in
exponential backoff.
Use this to resume immediately after a long network outage is
resolved.
.El
.Sh FILES
.Pa /var/yp/binding/<domain>.version
- binding file for <domain>.
.Pa /var/yp/binding/<domain>.ypservers
- explicit list of servers to bind to for <domain>.
.Sh DIAGNOSTICS
Messages are sent to
.Xr syslogd 8
using the
.Dv LOG_DAEMON
facility.
.Sh SEE ALSO
.Xr domainname 1 ,
.Xr ypcat 1 ,
.Xr ypmatch 1 ,
.Xr ypwhich 1 ,
.Xr nis 8 ,
.Xr yppoll 8 ,
.Xr ypset 8
.Sh AUTHORS
.An -nosplit
This version of
.Nm
was originally implemented by
.An Theo de Raadt .
The ypservers support was implemented by
.An Luke Mewburn .