[Openswan Users] Packets show up twice in tcpdump

Michael Smith msmith at cbnco.com
Wed Aug 23 09:46:41 EDT 2006

On Wed, 23 Aug 2006, Mihajlo Cvetanović wrote:

> > The virtual interface in KLIPS is nice for troubleshooting but it doesn't
> > work with dynamic routing.

> Could you elaborate more on this, please? I've never needed to work with
> dynamic routing, but in case the need arises this info would be helpful. I was
> under the impression that KLIPS doesn't prevent you from doing something you
> were able to do before.

It's actually not the virtual interface that causes problems, but what 
happens after the packets are encapsulated.

With KLIPS, you have a route to the remote tunneled subnet via, say, 
ipsec0. KLIPS grabs the packet and forwards it to the remote peer using a 
statically configured nexthop from ipsec.conf. There is no way to use a 
dynamic route to the peer.


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