Re: SNAT before IPSec

[Jorge Davila <davila@nicaraguaopensource.com>]

Let me know if I'm wrong... Are you trying to modify the source address of 
the packets before the packets get encryption?

Jorge.

On Wed, 6 Jun 2007 00:29:51 +0300
  "noa levy" <noalevy@gmail.com> wrote:
> Thanks for all the help so far.
> Jorge - I'm actually using the native 2.6 kernel ipsec (netkey) and
> not KLIPS, so I don't have the "ipsecN" virtual interfaces and can't
> use that.
> In response to Grant's reply - I think I have a problem, since I'm
> using the 2.6.10 kernel (can't upgrade anytime soon). Can anyone point
> me to where I can find the relevant ipsec patches that enable the
> double passage through netfilter hooks?
> Thanks,
> Noa
> 
> On 6/5/07, Jorge Davila <davila@nicaraguaopensource.com> wrote:
>> I'm guessing that you can use the "normal" approach and apply the SNAT 
>>rules
>> to the outgoing traffic flowing in the ipsec interfaces.
>>
>> The ipsec encryption algorithm is a kernel space tool and iptables is a 
>>user
>> space tool to the netfilter kernel module.
>>
>> All traffic that pass the POSTROUTING chain in the NAT table is leaving 
>>the
>> firewall box (through a physical interface e.g.:eth0 or through a virtual
>> interface e.g.:ipsec0).
>>
>> Jorge Davila..
>>
>> On Tue, 5 Jun 2007 15:29:47 +0300
>>  "noa levy" <noalevy@gmail.com> wrote:
>> > Hi All,
>> >
>> > I have a setup where I need to SNAT traffic that will be going out via
>> > an IPSec tunnel. The NAT must take place before the IPSec
>> > encryption+encapsulation, so I need the packet to first go through
>> > SNAT and then match an IPSec policy. After being IPSec-ified, I need
>> > the packets to go through routing again.
>> > My question:
>> > SNAT takes place in POST_ROUTING. Can IPSec be applied after that? I
>> > have read that after IPSec the packet gets injected to LOCAL_OUT
>> > again, but when does the actual IPSec policy decision take place?
>> > Won't it happen *before* SNAT? Can I control it?
>> >
>> > Thanks,
>> > Noa
>> >
>> >
>>
>> Jorge Isaac Davila Lopez
>> Nicaragua Open Source
>> +505 430 5462
>> davila@nicaraguaopensource.com
>>
> 

Jorge Isaac Davila Lopez
Nicaragua Open Source
+505 430 5462
davila@nicaraguaopensource.com