>On Sat, 6 Apr 2002, Crist J. Clark wrote:
>> On Sat, Apr 06, 2002 at 01:57:44PM -0600, Nick Rogness wrote:
>>
>>> On Fri, Apr 05, 2002 at 06:48:09PM -0600 I heard the voice of
>>> On Fri, 5 Apr 2002, Matthew D. Fuller wrote:
>>>
>>> You MIGHT be able to use ipfw divert/pipe rules to somehow shove the
>>> packets into a program on their way out, and write a program that
>>> would use raw sockets to hand-assemble the IP datagram on the way out;
>>> I'm not sure if the kernel would try to outsmart you on that.
>>
>> Yeh, I thought of that. The problem is packets never leave
>> anywhere since the route for the other NIC is not "OUT" any
>> interface...it is the machine itself.
>
> They never go over a _physical_ inteface, but they _do_ cross an
> interface, lo0, the internal loopback.
>
> ipfw fwd <external gateway> ip from <ip_if0> to <ip_if1> in via lo0
AFAIK, the route to get from 1 interface to the other is not
through the lo0. I'm not sure if the kernel sends these packets
across lo0 (internally) or not. But the routing table would
suggest not. Here is a snapshot of a machine with 3 network cards
in it:
lightning# netstat -rn
Routing tables
Internet:
Destination Gateway Flags Refs Use Netif
default 10.0.1.17 UGSc 6 472 tl0
10.0.1.16/28 link#1 UC 0 0 tl0 =>
10.0.1.17 0:a0:c9:5e:6:6 UHLW 7 273 tl0
10.0.1.31 ff:ff:ff:ff:ff:ff UHLWb 1 31965 tl0
10.0.3/24 link#3 UC 0 0 de1 =>
10.0.3.255 ff:ff:ff:ff:ff:ff UHLWb 1 31965 de1
10.0.5/24 link#2 UC 0 0 de0 =>
10.0.5.255 ff:ff:ff:ff:ff:ff UHLWb 1 31965 de0
127.0.0.1 127.0.0.1 UH 0 5288 lo0
Nick Rogness <[EMAIL PROTECTED]>
- Don't mind me...I'm just sniffing your packets
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