[vpnc-devel] Dhcp and host-route

[Bertho Stultiens]

[snip]
> I am running tcpdump on eth0 and tun0 for details. I will post them as
> soon as I have more details.

I now have dumps from both interfaces.

The broadcast to rebind is correctly sent through eth0 directly to the
outside net. The problem here is that I sometimes miss the answer. This is
obviously a problem in the communication between me and the ISP and not vpnc.

However, the unicast request to renew is, as predicted, sent through the
tunnel (my net 82.x.x.x/19, dhcp server 130.y.y.y/32). This can only be
solved by adding an explicit host-route to the original default gateway.

So the problem boils down to getting the correct address of the dhcp-server.
It is possible to find the lease in /var/lib/dhcp/dhclient-eth0.leases (on
my system) and then extract "dhcp-server-identifier" from that. Something
like this would do the trick:

$ grep dhcp-server-identifier /var/lib/dhcp/dhclient-eth0.leases | \
     head -1 | awk '{ print substr($3, 0, length($3)-1) }'

How generic this is, I don't know. Anyhow, at least it needs to be
discovered first that dhcp is used at all for the particular interface.


-- 
Greetings Bertho

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