What application are you using to setup the RTP stream? If you are using RTSP, I posted an RTSP NAT module for kernel 2.4.21-preX a couple of weeks ago that may solve your problem. On Sun, Apr 27, 2003 at 08:24:31AM +0200, Nils Ohlmeier wrote: > Hello, > > i try to NAT RTP streams with my own application (i do not use iptables to > insert the rules -> should i go to netfilter-devel?). > > Scenario: > 192.168.0.114 <-----> 192.168.0.2 > Netfilter NAT > 217.224.223.167 <--------------> 195.37.77.110 > > The result is that packets go from private to public but not vice versa. And > the ruleset looks like this (empty chains omitted, ruleset is only for > debuging, masquerade rule is for keeping my existing connections): > > Chain FORWARD (policy ACCEPT 237 packets, 47356 bytes) > pkts bytes target prot opt in out source > destination > 0 0 ACCEPT udp -- * * 195.37.77.110 > 192.168.0.114 udp spts:18554:18555 dpts:8766:8767 > 399 79648 ACCEPT udp -- * * 192.168.0.114 > 195.37.77.110 udp spts:8766:8767 dpts:18554:18555 > > Chain PREROUTING (policy ACCEPT 3481 packets, 552K bytes) > pkts bytes target prot opt in out source > destination > 0 0 DNAT udp -- * * 195.37.77.110 > 217.224.223.167 udp spts:18554:18555 dpts:32790:32791 > to:192.168.0.114:8766-8767 > > Chain POSTROUTING (policy ACCEPT 660 packets, 52480 bytes) > pkts bytes target prot opt in out source > destination > 0 0 SNAT udp -- * * 192.168.0.114 > 195.37.77.110 udp spts:8766:8767 dpts:18554:18555 > to:217.224.223.167:32790-32791 > 9 1835 MASQUERADE all -- * * 192.168.0.0/23 0.0.0.0/0 > > What i do not understand is why the packets from internal hit the rule in > FORWARD but do not hit the same rule in POSTROUTING. > The second strange thing is that packets come in on the external interface > (observed with ngrep) but to not hit the PREROUTING rule. > I fear i missed something obvious :-( > > Any help/ideas appreciated. > > Greetings > Nils Ohlmeier -- Guilty until proven innocent: abusing the legal system in the name of the war on terror. http://www.wired.com/news/conflict/0,2100,58326,00.html
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