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Background: I have tried to use routers, but so far all of them can't handle the bandwidth, number of connections eventually limited by the hardware resources, so overall the home routers are decreasing the internet speed. I went through DD-WRT and stuff like that.

Question: What I want is to use my Windows7 PC as router. It has 2 LAN cards. I'm going to connect to this router another desktop 2 pcs and notebook through wireless router. The main question is what is the most efficient way to turn this Windows7 box(and I need Windows for native NTFS support) into router with NAT/Routing/Firewall functionality?

Is there any routing software recommended for this purpose or I should just use windows native "Internet Sharing"? I'm going to run SIP phones in the LAN, so I need friendly NAT(Full cone perhaps). Also I'm going to have FTP server on that Windows7 "server" PC.

As firewall I'm thinking about Comodo. Need to drop all incoming, unless explicitly allowed.

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up vote 1 down vote accepted

Nobody actually answered the question so far.

You can do this using 2 possible approaches.

  1. Use internet connection sharing on your Win7 PC. (I last set this up on XP but I think it is much the same).This effectively turns your PC into a router doing NAT. You set this up so that one adapter is shared to the other, normally its used to make a gateway PC on a LAN, where there are 2 LAN cards - one connected to your ISP through a modem (or another router). The other is connected to your LAN. I have had such an arrangement running in a small commercial enterprise for several years and it works fine.

  2. For just plain routing of packets between 2 DIFFERENT networks, there is a registry hack you can google which will enable packet routing in Windows. You need to ensure that both adapters have different network numbers. For example, if both as Class C networks (subnet mask, then you might have adapter 1 (and all IP addresses therein) set to and adapter 2 (and all IP addresses therein) set to I had this arrangement working for several years on my home LAN because I was too tight to buy a switch but I had a cheap spare LAN card. It can get a bit messy but it does work.

When all this turns to custard, Wireshark is your friend for snooping packets!

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A Registry hack which I can google. Nice! Is that the reason I came here to find out that? This is not an answer, it's a redirect. – Thomas Jul 6 at 13:10

Using a PC will actually be slower. It's not designed to route traffic. It's better to have a dedicated device to do so. Look at some Linksys equipment, and if that doesn't cut it, look at some of the low/mid range Cisco routers.

  • What's your Internet connection speed?
  • What are the network cards/adapters being used in your PCs?
  • Are you using torrents? Those tend to establish a high number of active connections if not configured properly.
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My network connection is 100Mbit/sec, actual download speed average is about 2-4MByte/sec from different locations. Network cards are Realtek gigabit and built in adapters. Yes, I'm actively using torrents and I need to have multiple connections. Those are private torrents, not public, so all connections are actually increasing my rating. When PC connected directly to internet, there is no issue, while with router overall speed is decreasing dramatically and I can see router CPU/Mem usage is going to peak. I would prefer to use existing PC based hardware. – Pablo Aug 19 '10 at 4:41
There's a balance that has to be struck with the number of connections that are initiated by your torrent client. Too few, and your download/upload speeds suffer. Too many, and you start seeing networking issues. Using a PC as a router will not solve this issue. Configure your torrent client properly, see here for some suggestions: – Force Flow Aug 19 '10 at 12:07
I agree with Force Flow. I think you'd be wasting your time trying to use a PC as a router. – MetalMikester Dec 22 '10 at 0:42

Maybe you should consider Linux instead of Windows 7. Windows 7 is not designed to be a router OS. There are many Linux distributions that can handle your complex requirements.

Also, Windows 7 is expensive, if you use it as a router. Linux is normally free.

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I wouldn't say my requirements are complex. All I need is native NTFS support and uTorrent client. Not sure if can find similar client under Linux. FTP server is fine, even had one installed on router. The thing is I already have Windows 7. – Pablo Aug 19 '10 at 4:46

If you want to do it on windows, you can add a static route to each of your interfaces.

Note: make sure your NICs can handle the bandwidth.

You'll have to add static routes to the IP Networks at each NIC from command prompt (or make a batch file to use only when required) :

route add destination-address mask subnet-mask gateway-ip


route add destination-address mask subnet-mask interface-index-number

Or if you want to simulate a high end router like cisco or juniper, u'll need to use GNS3, you can try this out.

You can stop here if you already know how.

Place a router and connect two clouds to two of the router's interfaces. At the cloud configuration, assign each cloud an NIC from your PC. So now you have one cloud connected to each of the PCs NIC cards. Assign IP addresses on router and clouds. This basically results in both networks at your PC's NICs being connected to your router in GNS3.

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Adding a route does not help. It will only route packets that are already inside the PC. The problem is that packets which are outside the PC will not get inside that easily, because the PC thinks it's not for him. – Thomas Jul 6 at 13:09
Did you set the gateway IP address at the other PCs/devices at both LANs as the IP at the corresponding LAN interfaces at the 'router' PC? – Nithin Kumar Jul 14 at 11:05

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