Talk:Port forwarding
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BLA Can someone expand this entry to give a general description of how to set up port forwards? In particular, is there software that can forward UDP (as well as TCP) ports? With a general application, what's the best way to determine the ports that need to be forwarded?
- Yes, UDP can be forwarded just like TCP can. The article just says "network port", it doesn't exclude UDP. It wouldn't be wise to answer the first and the third question in the article, because Wikipedia is not a place for HOWTOs or cookbook entries that go this much beyond the main topic of the article. Well, the first answer would be borderline, but the second is way off-topic. --Joy [shallot] 21:51, 30 Dec 2004 (UTC)
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- The software you are talking about is found in the router. You access is through some IP (for example 10.0.0.138), you find NAPT or NAT and add an entry there. What I think is very relevant to this article though is UPnP, available in Windows XP, which enables programs to map these ports by themselves without user intervention. VodkaJazz 01:16, 13 January 2006 (UTC)
[edit] "can't see"
Hi! Can anyone confirm that the destination machine within the LAN "can't see" the sender of forwarded packets? I'm no expert, but AFAIK, in port forwarding the router only changes the destination IP so that a packet can reach a private IP -- it doesn't change the sender. That's part of the router acting as gateway. Thus, when the receiving end of the first packet responds, it sends a packet with the proper destination IP through the router acting as gateway. The latter, then, will appear as the sender of the packet, but it won't need to change the destination IP.
In other words, the machine within the LAN can clearly reach the one outside of it. It is the external machine which can't directly "see" the machine in the LAN.
I don't have much theoretical background, here, yet I can easily see the sender of a packet on my NATted, "port forwarded" machines. A router acting as gateway doesn't appear as the sender of a packet to NATted machines. Aside 21:05, Mar 21, 2005 (UTC)
Actually, it depends on how exactly the port forwarding was set up. The simplest setup is to change only the destination address (and possibly port). This works fine for connections originating from the exterior interface of the router, but does not work for connections from LAN to LAN - if A connects to router:80, which is rewritten to B, then B will reply directly to A, which is expecting a reply from the router and discards the packet. The rewriting of the source address is to fix this problem. It should only be done to packets originating from the LAN, however. DanielDeGraaf 02:30, 13 April 2006 (UTC)
[edit] port address translation
What is the difference between port forwarding and port address translation? — Omegatron 15:44, August 23, 2005 (UTC)
- The latter refers to a specific use of port forwarding, on gateways that also do network address translation. Those devices do a series of forwardings of ports to various destinations in the internal network. --Joy [shallot] 01:54, 24 August 2005 (UTC)
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- there is no port-forwarding (except on the same host) without NAT, because otherwise the destination host wouldn't accept the packets because they're addressed to him. PT and port forwarding are the same.--Penosa22 23:01, 19 February 2007 (UTC)
[edit] Information for Macintosh Users?
IF someone has some information on how to do this for macintosh users, I think it would be very helpful to add, either here or in another entry. thank you.
[edit] Keep The Articles Separate
"Port Forwarding" should remain a separate article because people look for it. Everyone has seen "port forwarding" in a firewall, but who has even heard of "port address translation?" Even if by arcane logic "Port Forwarding" is a subset of "Port Address Translation," an encyclopedia needs to have the aritcles people seek and "Port Forwarding" is a big topic in itself. The articles could be cross referenced. —The preceding unsigned comment was added by 70.22.209.112 (talk) 03:11, 17 March 2007 (UTC).
