[LARTC] Re: iptables rule not matching after stream begins

[Bob Beers]

Trying again, after re-subscribing:

On 11/20/06, Bob Beers <bob.beers at gmail.com> wrote:
> Hello,
>
> I want to dynamically create DNAT rules for
>  RTP streams (port-mapping for a SIP proxy).
>
> If my proxy adds the rule before the first packet
>  of the RTP stream hits the port, all is well.  But, if
>  the stream begins arriving before my rule is in
>  place, it never matches.  I cannot always be
>  sure that the info for setting up the rule
>  arrives sufficiently ahead of the stream.
>
> I suspect if there is a simple resolution to my
>  problem.  Does anyone else see this behavior,
>  and will share with me the solution?
>
> Apologies if there is a better place to seek an
>  answer to this question, please redirect me as
>  necessary.
>
> I am using kernel 2.6.15.4, and iptables 1.3.3.
>
> My rules are similar to this:
> iptables -I PREROUTING -t nat -p UDP \
>   -d<public_ip> --dport <public_port> \
>    -j DNAT --to-destination <private_ip:port>
> iptables -I FORWARD -p UDP \
>    -d <private_ip> --dport <private_port>
>
-- 
-Bob