Directly Connecting Two Computers

Updated: 28th December 2007

Connecting two computers together is not as straight forward as you might think, but it's not rocket science. This guide walks you though connecting two Windows XP machines via Ethernet using a cross-over cable.

Many homes nowadays have more then one computer, usually you can connect them via a wireless router that comes with your broadband connection, or via a switch, however if you have two computers that you want to connect without using a switch or Internet connection, then you'll need a cross-over cable.

Why Connect Directly?

Connecting two machines together without an Internet connection may seem a little pointless, but it's actually very useful if you need to transfer large amounts of data between the two, and they both have Gigabit Ethernet on board. Without other traffic to interfere, the two machines can use all the available bandwidth, and transfer data at near gigabit speeds.

What Is A Cross-over Cable?

In order to connect two machines directly to each other, you'll need a different type of ethernet cable then you'll normally use to connect to your router\switch\floor or wall port - a cross-over cable. A cross-over cable looks like any other standard ethernet cable, with one exception - the cables inside are twisted over to allow the transmitting pin to receive, and vice-versa. This removes the need for the switch, which normally does this conversion.

You can purchase cross-over cables at most IT related stores, or have them made out of normal Cat5 (or Cat5e) cable.

Connecting...

Physically, the connection is easy, Simply connect the cable to each Ethernet port on the machines. your Computers may inform you they are connected, but they will not speak to each other just yet. Remember to turn off any firewalls you might have on each machine. Since we are not connected to the Internet (unless your using Wireless also), they will just get in the way, so best to turn them off for now.

If you've read the guide on IP addressing, you'll know that each machine on a network (no matter how small), will need a unique IP address. Since IP addresses come from DHCP servers (Windows XP by default is not a DHCP server), then you'll need to manually configure each machine with an IP.

Let's assume for now that APIPA didn't get in the way and we are ready to proceed. Before you do, it's important to know if your machine already has a static IP, since we need to set one. If you know one or more of your machines already has a static IP, then you'll need to make a note of those settings, so you can put them back later.

Let's start by configuring the first machine, called Machine 1.

On the desktop, or in the Start Menu, should be an icon called 'My Network Places'. Right click it and select 'Properties'.

You should have an icon in the new Window which appears called 'Local Area Connection', and directly underneath it should be the name of your network adapter, mostly containing the text '10/100', and be shown as status 'Connected' (assuming you've connected the cable and it is indeed - a cross-over).

Right click the icon, and select 'Properties'. the new window which appears is the Local Area Connection Properties Window. It should look similar to the following:

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Within the list of items should be 'Internet Protocol (TCP/IP)'. Highlight this item, and click 'Properties'. (There are a lot of properties!).

You should see the screen below:

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This window shows you everything you need to know about your IP address details, if your machine has been left with default settings, then it will most likely be set to 'Obtain an IP address automatically', like the example above. However if it is set to 'Use the following IP address:', then your already configured for a static IP. Continuing will cause you connection problems on your main network should you change these settings. If you want to continue, make sure you write down the IP address, Subnet mask, Gateway, and DNS server addresses.

For this howto, we are going to use a private IP range which is commonly used in home networks, to make sure our machines don't conflict with other devices should they be connected to another network with our static IP's, we'll use addresses at the higher end of the range.

Enter the IP address details as shown below:

(Click on image to enlarge)

Let's go over the settings:

IP address: Each machine on the network needs a unique IP address. Machine 1 will use this one. Each IP address must contain 4 octets (x.x.x.x), any of which cannot be higher then 255.

Subnet mask: The subnet defines which network our IP addresses above belongs to. IP address ranges can be split into different subnets allowing for much larger complicated networks. For our small 2 PC network, we'll use the simplest subnet mask.

Default gateway: The default gateway tells our machine where to go if it cannot find any other machines. Since our network doesn't actually go anywhere, this address is irrelevant and could actually be anything.

Preferred DNS server: You can enter two DNS servers, but the second is optional, however for our network, we do not need DNS. DNS simply resolves IP address to names of machines, large networks and the Internet could not work without it, but since we know where our machines are, we don't need it.

That's all the settings we need. You'll also need to enter the details on Machine 2, with one difference. The IP address needs to be unique so we will change that. Repeat the above steps and enter the following for Machine 2:

(Click on image to enlarge)

Once you've OK'd each machines network properties, Windows should inform you it's connected:

You can go ahead and verify the machines IP addresses have been stored by Clicking Start -> Run, and typing in 'cmd'.

Once the black command prompt opens, type 'ipconfig'. You should receive the following output. The IP address has been highlighted so you can see what to look for:

(Click on image to enlarge)

That should be all there is to it. One final test is to 'ping' each machine to see if they really are talking. Using the same black prompt from before, enter the command 'ping' followed by the IP address of the other machine, you should see replies from the destination:

(Click on image to enlarge)

If however, they do not reply, and you receive packet loss errors, then the machines will not work on any other level, check back through the steps above.

If your ping replies, we are all set! Go ahead and see which shares are available, on any of the machines, click Start -> Run and type into the run box the IP address of the other machine, once you click OK, you'll either be presented with a username\password prompt, or a Windows folder detailing the shared drives on the machine.