UDP forwarding trouble

UDP forwarding trouble

[Pierre JUHEN]

I have a problem with iptables.

This is the configuration

+---------+                 +---------+                 +---------+
|         |                 |         |                 |         |
|    A    +-----------------+    B    ++----------------+    C    |
|         |                 |         |                 |         |
+---------+                 +---------+                 +---------+

A sends UDP packets (ports p1, p2, p3) to C through B.

There is a continuous flow of UDP/p1 packets (10 packets/s) whilst
p2 and p3 are more seldom.

When I activate a rule to  redirect all UDP packets from A to B
the rule seems to be applied only to p2 and p3 ports, p1 packets
are still forwarded directly.

Is there a form of caching mechanism that explains the fact that
the packets are treated differently ?

Thanks for your help

Regards,

Pierre JUHEN

Re: UDP forwarding trouble

[Nick Drage]

On Mon, Jul 25, 2005 at 09:28:28PM +0200, Pierre JUHEN wrote:
> I have a problem with iptables.
> 
> This is the configuration
> 
> +---------+                 +---------+                 +---------+
> |         |                 |         |                 |         |
> |    A    +-----------------+    B    ++----------------+    C    |
> |         |                 |         |                 |         |
> +---------+                 +---------+                 +---------+
> 
> A sends UDP packets (ports p1, p2, p3) to C through B.

If the packets are being sent from A to C...

> There is a continuous flow of UDP/p1 packets (10 packets/s) whilst
> p2 and p3 are more seldom.
> 
> When I activate a rule to  redirect all UDP packets from A to B
> the rule seems to be applied only to p2 and p3 ports, p1 packets
> are still forwarded directly.

...why do you need to redirect packets?

Are you sure that the three rules ( presumably ) dealing with the three
ports are all the same?  Can you post the rules here, with the necessary
obfuscation of course.

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