<html>
<head>
<meta http-equiv="content-type" content="text/html; charset=ISO-8859-1">
</head>
<body bgcolor="#FFFFFF" text="#000000">
In a valid IPv4 configuration, the IP address of every interface on
a device has to be different. So the --listen-address parameter
specifies particular IPv4 addresses, and those are unique on the
box, each IPv4 address appears on 1 and only 1 interface. So
--listen-address is easily used to specify what is required, without
needing --interface.<br>
In IPv6, the link-local address can be the same on multiple
interfaces. This can happen by design - e.g. every LAN interface on
a router is set to fe80::1 - or in a scenario with some sort of
virtual interfaces running on a physical NIC, the software might use
the same underlying MAC address of the NIC to generate the
link-local address. So all the VPN interfaces, or VLAN interfaces or
whatever turn out to have the same link-local address. I believe
this is all valid in IPv6. (Stop here and tell me if it is not!)<br>
This makes it not possible to use --listen-address for IPv6
link-local addresses that appear on multiple interfaces. (unless you
do happen to want to listen on them all)<br>
If you want to listen to both IPv4 and IPv6 on a set of interfaces,
then you can use --interface and/or --except-interface - but that
can also be tricky "IP alias interfaces (eg "eth1:0") cannot be used
with
<b>--interface</b>
or
<b>--except-interface</b>
options, use --listen-address instead". And what if someone does
want to listen to some mixture of IPv4 and IPv6 addresses on
particular interfaces.<br>
There is a discussion about this on pfSense:
<a class="moz-txt-link-freetext" href="http://forum.pfsense.org/index.php/topic,65109.msg353680.html#msg353680">http://forum.pfsense.org/index.php/topic,65109.msg353680.html#msg353680</a><br>
My question is, when an IPv6 address is duplicated on multiple
interfaces, is there a way to specify listening on a particular
combination of IPv6 address+interface?<br>
</body>
</html>