From mboxrd@z Thu Jan  1 00:00:00 1970
From: Patrick McHardy <kaber@trash.net>
Subject: Re: How to find I/F to destination
Date: Fri, 04 May 2007 15:00:01 +0200
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To: David Howells <dhowells@redhat.com>
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David Howells wrote:
> I would like to determine through which interface packets sent to a particular
> UDP destination will go through, and so determine the MTU size for that
> interface.  Can anyone suggest a good way of doing this from within the
> kernel?


Do a route lookup (ip_route_output_key), then either use dst_mtu to get
the PMTU value or dst->dev in case you really want the device's MTU.