[Live-devel] A network problem

[fung ka luen]

In my case, almost all NAT will not allow the RTP packet pass-through. I do believe that the NAT(router) actually don’t know where the packet should send to. 
Before the server(S) sent the RTP packet to the client(C) , S-C only have a TCP connection for RTSP. The NAT (router) can’t read the RTSP (application layer). Therefore, it will not do everything else to help the RTP.  In this case, all the RTSP runs OK but nothing on RTP can be received.
 
Solutions:
1)      If you have access to the NAT device, the port “forwarding” can help. A pair of RTP/RTCP port in your client had to be fixed first and set the port-forwarding in the NAT. 
2)      If only one client is needed to receive the RTP packet, the client can put in DMZ. ( all port forwarded to the PC(Client) in the DMZ)
3)      According to the RFC 3550, it has mentioned an item called “translator”. it can help to connect the S-C in the firewall or NAT protected environment. I think it have to read the RTSP information and create a tunnel for those blocked incoming RTP/RTCP (S->C). 
Actually, I am not 100% sure what the translator is. I know what it should do but not know how it works and how to construct or any open-source is available in the world. I am working on right now. By using this Translator, I do believe that a technique called “Hole Punching” would help. If “Hole Punching” used as a keyword, Tons of documents can be found in the web. 
 
Hope it information may help.
 
KL Fung

 
> ----------------------------------------------------------------------> > Message: 1> Date: Mon, 3 Mar 2008 17:13:31 -0600> From: xcsmith at rockwellcollins.com> Subject: Re: [Live-devel] A network problem> To: LIVE555 Streaming Media - development & use> <live-devel at ns.live555.com>> Message-ID:> <OF2C2943F0.2787B92F-ON86257401.007E23EF-86257401.007FF8FA at rockwellcollins.com>> > Content-Type: text/plain; charset="us-ascii"> > > In general, you cannot expect RTSP/RTP to work over a NAT. However,> > because your server is really on the Internet, then you might be > > able to get RTP-over-TCP streaming to work, even though your client > > is not really on the Internet.> > Is the IP address the only problem with NAT? Couldn't routers with > correct port forwarding (on either end of the RTSP connection) take care > of this?> Also, I notice a lot of posts about UDP transfer problems. Is the primary > reason that firewalls are often blocking UDP? RFC 2326 1.4 Claims that > passing the Transport Initialization Information in the RTSP messages > allows routers to open the firewall as necessary. Do any commercially > available routers/firewalls actually allow this for RTP? Based on posts > so far, it sounds like if you have a firewall, you're SOL without > RTP-Over-TCP.> > RFC 2326, Section 1.4 Protocol Properties> " Proxy and firewall friendly:> The protocol should be readily handled by both application and> transport-layer (SOCKS [14]) firewalls. A firewall may need to> understand the SETUP method to open a "hole" for the UDP media> stream."> -------------- next part --------------> An HTML attachment was scrubbed...> URL: http://lists.live555.com/pipermail/live-devel/attachments/20080303/500863a8/attachment-0001.html > 
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