[LARTC] IPSec tunnel and routing

[LARTC] IPSec tunnel and routing

[Alexander Kotelnikov]

Hello.

I wonder how just correct couple of spdadd commands like

spdadd 192.168.1.0/24 192.168.2.0/24 any -P out ipsec esp/tunnel/10.1.0.1-10.2.0.1/require;
spdadd 192.168.2.0/24 192.168.1.0/24 any -P in ipsec esp/tunnel/10.2.0.1-10.1.0.1/require;

makes _routing_ of packets from 192.168.1/24 into 192.168.2/24.

If I understand correctly how it works on *BSD, these commands with
make already tunneled traffic enrypted, routing is done before and
besides ipsec SA and SP databases. On routing happens just like
miracle.

Ok, I would not ask all this if I have no problem with
tunnelling. With configuration like described above, where multihomed
maches have ip-addresses (192.168.1.1, 10.1.0.1) and (192.168.2.1,
10.2.0.1) tunneling works for all machines, but these two
routers. This happenes becase if we send a packet from 10.1.0.1 into
192.168.2/24 this packet does not come to ipsec, but is pushed to
default gateway, if it exists. In other words, local generated packets
do not come through prerouting or something.


-- 
Alexander Kotelnikov
Saint-Petersburg, Russia

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Re: [LARTC] IPSec tunnel and routing

[Andreas Unterkircher]

Alexander Kotelnikov schrieb:
> Ok, I would not ask all this if I have no problem with
> tunnelling. With configuration like described above, where multihomed
> maches have ip-addresses (192.168.1.1, 10.1.0.1) and (192.168.2.1,
> 10.2.0.1) tunneling works for all machines, but these two
> routers. This happenes becase if we send a packet from 10.1.0.1 into
> 192.168.2/24 this packet does not come to ipsec, but is pushed to
> default gateway, if it exists. In other words, local generated packets
> do not come through prerouting or something.
>   
You have to add a route on 10.1.0.1 to make sure packets which belong to 
192.168.2.0/24 have
a src address of 192.168.1.1. Then the packet should go through the 
ipsec tunnel. Similar route in
the other direction has to be used on 10.2.0.1.

Cheers,
Andreas

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