HOW TO: Fix the annoying mw2 NAT problem

mobusta1

2[H]4U
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May 1, 2008
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I've noticed a few people are having problems with "Strict NAT" and having trouble playing online.

Various posts I've read on the web have recommended all sorts of things... I'm going to add my own 2 cents, as I have some major disagreements with most of what's being said.

The two most commonly recommended fixes (including the one from infinity ward themselves) are complete bull in my opinion.

Now infinity ward recommend that you enable UPnP on your router. Don't. In fact I'd go as far as saying "Fuck that." UPnP is a known vulnerability. If you configure your network properly, forward ports properly etc, you'll have a safer more reliable connection. But if you want to listen to the people who thought it'd be a good idea to remove dedicated servers and mods go to http://www.infinityward.com/nat.php

Other sites suggest adding your PC to the DMZ. Don't. DMZ stands for "DeMilitarized Zone". As such, anything in the DMZ is effectively NOT protected by the router in any way. This is fine for an Xbox360 or PS3, but I wouldn't do it with a PC. Again, a properly configured network connection, with properly forwarded ports is safer, and more reliable.

So what do I suggest? Well obviously properly configuring your network and forwarding the ports. But for the less tech savvy crowd that's easier said than done. There's not an awful lot of work involved, but there are many terms and phrases that may be confusing, and many of the guides out there offer faulty information.

Now to the point: I'm going to help you get your network/ports setup, and I'm going to give a few pointers on bits of the other guides out there that in my opinion are crap...

You will need to have access to your router's login details, and I'm writing this guide assuming you've already updated everything, including motherboard drivers (especially network drivers).

You also need to have your network setup in a standard configuration, for instance; Phoneline-DSL lead-modem (if yours is seperate from your router)-Router-ethernet lead-PC

Other configurations, such as connecting through another PC that inturn connects to the router, or going through multiple routers or a hardware firewall etc, will require more work.

This guide is here for informative purposes. It may contain errors, or because of your network setup it may not work for you. Some ISP's may even require that you have DHCP or UPnP enabled. If that's the case I can't help you. Some ISP's even block p2p connections, in which case you're SOL

This is how mine's setup, and it works flawlessly, NAT type "open"

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1. Disable DHCP, UPnP, and DMZ in your router. Make sure NAT is enabled.

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2. You need to set astatic IP for your PC. There's a guide on how to do this at Portforward.com configuring a static IP. Which is all well and good, but there's an awful lot of pointless junk in it. You don't need to open CMD for one thing, it's easier (and less daunting to the average user) to login to your router and get the info it would give you from there.

Make a note of your "Domain Name Server" IP addresses, these are the DNS numbers you'll want to put in the following section.

Make a note of your Router's IP address, also known as the "Default Gateway".

Now, using the guide for Windows 7 as an example, you want to open your Network and Sharing centre (right click network icon in the toolbar, select "Open Network and Sharing Center", then follow the portforward guide from step 7. Pay special attention to step 10.

3. Forward ports through your router. Now the guide at portforward I haven't used for MW2. In fact I haven't forwarded any ports specifically for MW2. I do however have the CoD4 ports forwarded, so use the CoD4 guide, and do the port range 28960-29000 for both UDP and TCP. When it asks which server you want to forward the connection to, that will be your PC's IP address

Note that the above range doesn't even include the ports that portforward.com suggest (27014-27050), but I've got an open NAT, and if you're reading this you probably haven't. In fact I don't even have them ports open for anything else either. I never forwarded any ports for MW2, or CoD:WaW either. The portforwarding rules for CoD4 have them both covered. So use the CoD4 guide, and forward the above ports for both directions

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Now if you've done all this correctly you should have an open NAT. If not, carry on reading:

4. Make sure iw4mp.iw4sp.exe's are allowed through your firewall. Depending on your firewall you may also have to forward the ports through it, do the same ports as you have in your router, again for both UDP and TCP (you want traffic to go both ways).

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5. Still having trouble? Make sure your antivirus software isn't blocking the game from accessing the web. You'll need to go into the AV advanced settings and add iw4mp/iw4sp.exe's to your exceptions, so that your antivirus just ignores them.

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Hopefully this guide will help at least some of you get connected properly
 
I agree absolutely do not put your PC in the DMZ that's just a massive secuirty weakness.

As for uPnP that's fine, UPnP allows applications on your network to request to connect through the router both incoming and outgoing, most applications will happily set up their own network connections through your router automatically providing uPnP is allowed on. It's practical benefit is massive as you basically don't have to configure anything, if you disable uPnP you might have to go through a great deal of other applications and make specific rules for them by hand which is a huge PITA.

Disabling DHCP is also a bad idea, this assigns network addresses to anyone connecting, it means that devices simply will no connect to the router until you've manually entered all the correct information on your computer, if you have lots of devices you need to make sure people connecting and leaving the network all have unique IP addresses and again this is just a big PITA.

If you want to give your PC a static IP address you can still do this with DHCP on, simply set the IP range of the router to be less than the total allowed so do like xxx.xxx.xxx.50 to xxx.xxx.xxx.255 and then anythng you want to assign a static IP to you can just make it less than 50.

This is quite bad advice IMO and doesn't stress the downsides of doing these things, it going to cause the average user who doesn't know much networking, a huge amount of fututre problems with things not connecting or working automatically.

My advice would be just to check your router and make sure uPnP is enabled, if it is and you can normally connect to the net then CoDMW2 should work, if it does not and the firewall is set to allow it then its a bug with the game and the developers will need to address it, you shouldn't be needing to forward ports on your router, again this is a security risk it doesn't just filter traffic for MW2 those ports are open 24/7 for any application to use. A potential security risk.
 
Thanks for posting this here. I need to do this but I have been too lazy so far :eek:.

Are you by any chance FunkyMonkey80? I remember seeing this post on another forum...
 
i wouldnt say its bad advice per say.. sure some of it is like the DHCP stuff is.. having upnp off and manually opening ports both have their security risks.. upnp = any program can open any port it wants while manually opening ports leaves them open 24/7.. so really whats the difference.. for the average user most of these suggestions dont help that much.. for a person that already knows what they are doing they really dont help that much either since we already setup our stuff the way we want it.. so its up to the person that reads it.. while it may not help some it may help others that dont have a router with UPnP support.. there are also routers like mine that use port triggers.. so unless a program application requests that specific port to be opened it stays closed.. similar to UPnP but leaves all the other ports closed even if a program requests one of the ports i dont have forwarded.. but generally doesnt matter for me since im lazy and leave UPnP enabled..

btw anyone that recommends some one using DMZ needs to be banned from ever using a computer, let alone one that has internet access..
 
Don't static IP your machine, that's noob networking right there. Setup IP reservation via Mac address.
 
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