trying to revive rtsp

Mickael Marchand marchand at
Sun Feb 19 15:13:53 CET 2006


I am really a newbie to the netfilter coding world, so please forgive
any stupid questions :)

I have mostly ported the old rtsp conntrack+nat code to recent 2.6
kernels, compiles and loads fine into the kernel,
but I have some problems to make it work now :)

the initial TCP connexion to the RTSP server:554 is correctly detected
and the expectation packet seems to be properly setup :
cat /proc/net/ip_conntrack_expect
255 proto=17 src= dst= sport=0 dport=33302 is the RTSP server, is the client, is
the netfilter box.

so once the TCP connexion has been established, we expect a UDP stream
from the server going to the client port 33302.

my problem is that the expected packet does not get through the
netfilter box, I can see the UDP stream coming from the RTSP server and
going to my netfilter box,
the expectation packet seems to get removed of
/proc/net/ip_conntrack_expect as well (so basically it looks all good)
but the netfilter box does not forward packets to
so it looks like a NAT problem to me, maybe the UDP packets are not
getting NAT-ed back to the client.

my first question would be :
is it expected to see in the expected paquet ?
should not it be my external IP instead ?

any tips in what direction I could look ? :)

thanks for any help

(Please CC-me in answers :)

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