And documentation.

git-svn-id: file:///svn/unbound/trunk@3674 be551aaa-1e26-0410-a405-d3ace91eadb9

doc/example.conf.in

@@ -93,6 +93,11 @@ server:
 	# (uses IP_BINDANY on FreeBSD).
 	# ip-transparent: no
 
+	# use IP_FREEBIND so the interface: addresses can be non-local
+	# and you can bind to nonexisting IPs and interfaces that are down.
+	# Linux only.  On Linux you also have ip-transparent that is similar.
+	# ip-freebind: no
+
 	# EDNS reassembly buffer to advertise to UDP peers (the actual buffer
 	# is set with msg-buffer-size). 1480 can solve fragmentation (timeouts).
 	# edns-buffer-size: 4096

doc/unbound.conf.5.in

@@ -277,6 +277,13 @@ and with this option you can select which (future) interfaces unbound
 provides service on.  This option needs unbound to be started with root
 permissions on some systems.  The option uses IP_BINDANY on FreeBSD systems.
 .TP
+.B ip\-freebind: \fI<yes or no>
+If yes, then use IP_FREEBIND socket option on sockets where unbound
+is listening to incoming traffic.  Default no.  Allows you to bind to
+IP addresses that are nonlocal or do not exist, like when the network
+interface or IP adress is down.  Exists only on Linux, where the similar
+ip\-transparent option is also available.
+.TP
 .B rrset\-cache\-size: \fI<number>
 Number of bytes size of the RRset cache. Default is 4 megabytes.
 A plain number is in bytes, append 'k', 'm' or 'g' for kilobytes, megabytes