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I have a home wireless network and two laptops. My primary laptop is normal, and runs Windows 7. My secondary laptop has no wireless capability, and I have no access to the IP settings on my account. How can I access the internet on my secondary computer through my primary computer using a crossover cable or something similar? In other words, how can I make my primary computer produce a connection that my secondary computer will find indistinguishable from normal ethernet?

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why do you have no access to the ip settings? –  ubiquibacon Oct 22 '10 at 23:47
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3 Answers

Simply bridge the wired and wireless network connections of your primary laptop then connect the LAN ports of your two laptops via an Ethernet cable.

Bridging is easy, simply highlight your LAN connection and wireless connection in the Network Connections menu of your primary laptop, right click one of them and select Bridge Connections.

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Thanks for your replies. I tried this, but it didn't seem to work. Is there any reason this wouldn't work when plugging the second computer directly into the router does? –  jhioj Oct 22 '10 at 14:46
    
Make sure your second computer is set to get an ip address automatically. You shouldn't have any manual settings entered in the network configuration of the second computer. –  ubiquibacon Oct 22 '10 at 18:09
    
Won't the OP need a crossover cable for this? –  horatio Dec 30 '10 at 22:02
    
@horatio nope, regular Ethernet cable will work, the bridge will figure it out. –  ubiquibacon Dec 30 '10 at 23:00
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On a Windows computer with two network interfaces, it is also possible to turn on NAT using netsh. This used to work in Windows XP, not sure about newer ones, since I'm not using Windows anymore.

netsh NAT example

"external" - name of the external interface

"internal" - name of the internal interface

netsh> routing ip nat
netsh routing ip nat> install
netsh routing ip nat> add int "external" full
netsh routing ip nat> add int "internal" private
netsh routing ip nat> exit

Start the service "Routing and remote access"

You do this on the computer that has access to the internet. Set up a local IP like 10.x.x.x or 192.168.1.x on the internal interface of that computer. Set up a local IP from the same network on the second computer, also some valid DNS servers. At this point both computers should be able to ping each other, the second computer will get access to internet.

Should you need to do port forwarding to the second computer, it is also possible with netsh:

netsh port forwarding example

"external" - name of the external interface

"internal" - name of the internal interface

192.168.1.10 - IP address on internal interface

192.168.1.11 - IP address of LAN host

22222 - port to be forwarded

netsh routing ip nat add portmapping external tcp 0.0.0.0 22222 192.168.1.11 22222
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"Set up a local IP from the same network on the second computer, also some valid DNS servers." One of my difficulties is I can't change any settings on the second computer. –  jhioj Oct 22 '10 at 14:19
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You may want ICS (Internet Connection Sharing), though to be honest it'll probably be easier in the long run to purchase a USB wireless adapter.

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This is a way, but not the easiest way. Internet Connection Sharing is more appropriate when the connection needs to be shared with multiple computers. For his purposes simply bridging the network connections of his primary laptop should suffice. –  ubiquibacon Oct 22 '10 at 7:18
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