Re: SNAT before IPSec

[Jorge Davila <davila@nicaraguaopensource.com>]

Uhm ... well, may another approach works.

But, why reports another source IP address to the remote internal network???

Jorge Davila.

On Wed, 6 Jun 2007 01:40:34 +0300
  "noa levy" <noalevy@gmail.com> wrote:
> Yes, I want to change the source IP address of the original IP packet
> before encryption.
> 
> On 6/6/07, Jorge Davila <davila@nicaraguaopensource.com> wrote:
>> OK - Let me now if I'm wrong ...
>>
>> Are you trying to modify the source address of the packet before the 
>>packet
>> gets 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
>>
> 

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