Nat-pmp??

[fluttered]

After meeting and falling in love with utorrent I recently decided to try the 1.7 beta... all well and good and working (apart from my ISP capping my upload and throttling everything in an attempt to force me to change plans... *insert long explanatory vent here*! :icon_pale )

"...all well and good and working except for an error log saying "Unable to map NAT-PMP" every time I add a torrent.

I have no idea what nat-pmp is? I looked it up but still don't really understand what it is (beyond being mac program for windows?) or what it does...

Can any one assist my ignorance and tell me
a.) what it is?
b.) if my transfers will improve if I get it going
and c.) if b is yes then how would I go about doing that?

Muchas Gracias oh wise ones.... :)

x

[kaosfere]

NAT-PMP is an alternative to UPNP that works with Apple networking equipment. Both of these protocols are used to automatically configure NAT (Network Address Translation) on your network.

In short, when your machine is behind a router, it usually has an IP address that is different from your IP address on the internet. If this address, which is almost always in a "private" IP block that cannot be reached from the internet, were sent out in your traffic, no one would ever be able to respond to you. It is the router's job to take your internal IP address and change it to the outside one. Additionally, it needs to remember your traffic, so that when messages come back to your machine, it can pull out your public IP, put in your new one, and send them on to you. This whole process is called "Network Address Translation".

Usually, NAT only works for traffic that you originate: You make a request, it goes to the router, the router translates it for you, and gives the response from the remote host back to you when it comes. This is fine. However, things get more complex if you're trying to receive traffic without first sending -- such as when a P2P peer is trying to connect to you to get a file you have.

In this case, you have to preconfigure your router to know that when traffic comes in for it on a specific port, it is supposed to pass that on to you. If you don't do this, it will not respond to the incoming traffic, and you will effectively be unreachable to the world. In the "bad old days" this had to be done manually. Then a number of protocols came up (UPNP and NAT-PMP) which allowed applications which expected to receive incoming connections from the outside world to tell the router automatically, "Hey, I need to have traffic on port X sent to me", so that there was no need to set this information up by hand.

Now, as for your situation: if you don't have Apple hardware, you shouldn't need to have NAT-PMP enabled. The error is most likely because you have it turned on, and uTorrent is trying to talk to your router to set up a NAT-PMP config, then failing because your router doesn't talk NAT-PMP. If this is the case, it should be perfectly safe to turn this off. I've not used uTorrent, so can't give you the specifics on this, but a little bit of reading should give you the details.

You'll only see an improvement from using NAT-PMP if you're using network gear that uses this instead of UPNP -- which is pretty much just Apple gear, as I said. For most cases, UPNP, or no automatic NAT configuration at all, is all you need.

Hope this helps.