Tutorial:Static Internal IP Router

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A -VERY- important part of setting up a Static IP address on your computer is CHOOSING an appropriate number to assign to the computer as its permanent, “static” IP address.

There’s more to it than just picking any old number at random, and the number your computer has been using up until now may NOT be an appropriate choice.

This is because some routers may have trouble forwarding ports to IP addresses which conflict with their DHCP server address range. That is, if the IP address on the computer is the same as one which the DHCP server might assign, the Port Forwarding may FAIL.


So the FIRST step in setting up a Static IP address is to find out what range the DHCP server is set up for, and choosing a number that will NOT conflict with that range.


Log into your router and look for a page that tells what the DHCP Server configuration is. This is usually found under “Advanced Configuration” and then “LAN” (or similar wording).

Once you’ve found the DHCP Server page there should be one of two different ways of displaying the RANGE of addresses in the server.


The first is the simplest. It gives the “Starting Address” and the “Ending Address” (or “Low” and “High”)

Thus for example if you see:

 
Starting Address 192.168.0.100 
Ending Address  192.168.0.150 

The “Range” of the DHCP server is FROM 192.168.0.100 TO 192.168.0.150


The second way the DHCP Server range can be displayed is to give the “Starting Address” and the “Number of Clients” (or “Number of Addresses”)

Thus for example if you see:

Starting Address : 192.168.0.10 
Number of Clients:  50 

The “Range” of the DHCP server is FROM 192.168.0.10 TO 192.168.0.60 (50 addresses, starting at 10)


You must choose a number from 2 through 254 which does NOT fall within the DHCP server range, and which does NOT duplicate the address already being used by the router (the IP address you type to log into the router)..


So in the first example you would be safe choosing a Static IP Address for your computer of 192.168.0.151

And in the second example you could safely choose 192.168.0.61, because these numbers are OUTSIDE of the DHCP Server range.


NOTE- This is important!

The "Range" of the DHCP server is INCLUSIVE.

That means when we say (just for example, your router will probably be different) :

 
Start address 192.168.0.100 
End   address 192.168.0.150 

It means you CAN'T USE .100 OR .150 OR ANY of the numbers between them.



In most cases, all you’ll need to do is check the “range” of the DHCP server and pick a safe IP address outside that range for your computer.

BUT- there IS one situation which will require you to make a change to the ROUTER setup BEFORE you can go on.


If you discover the DHCP server is set to use ALL possible IP addresses, then that leaves NO safe addresses for YOU to use.

Starting Address 192.168.0.2 Ending Address 192.168.0.254 <-- This leaves NO addresses free for YOU to use.


If the DHCP server is set to use the entire range, from .2 through .254 then you will have to CHANGE the higher figure to something lower in order to free up some addresses that will be safe for YOU to use.


On the DHCP server page, CHANGE the “Ending Address” from .254 to something like .200

Starting Address 192.168.0.2 Ending Address 192.168.0.200 <-- This leaves 54 addresses free for YOU to choose.


That will make the “range” of the DHCP server from .2 through 200 then you can choose any address higher than .200, in this example, 192.168.0.205

Click the “Apply” or “OK” button, then if necessary, REBOOT the router to make the change take effect.


NOTE: VERY IMPORTANT!! We are picking the LAST set of digits in the IP address ONLY..!

The FIRST THREE sets of digits MUST be the SAME as the ones the router and the DHCP server uses.

Thus, if YOUR router uses 192.168.2.1, then you MUST pick a Static IP address that begins with 192.168.2

If YOUR router uses 10.0.0.1, then you MUST pick a Static IP address that begins with 10.0.0

Again- we’re ONLY changing the LAST set of digits.



Now that you’ve decided on a compatible Static IP address to use for your computer, follow this link for a guide to setting up the IP address on your computer-

However- SKIP the first few steps that tell you to look in IPCONFIG for the IP address, and just use the compatible IP address you've chosen with this guide.

Skip ahead to the step (#5 in the Windows XP guide) that tells you to open the Control Panel and follow the instructions from there.



http://portforward.com/networking/staticip.htm


Once you've finished this procedure, the address you decided on, and configured in Windows TCP/IP Network Properties will be your "Static IP Address".

Whenever anything asks for your computer's Static IP Address, this number is what it's asking for.



NOTE- If your Internet connection stops working when you change Windows to a Static IP address, the reason usually is that you need to find out what your "DNS Server" addresses are.

If you have this problem, read THIS guide for help on that:


http://forum.portforward.com/YaBB.cgi?board=Knowledge;action=display;num=1116580819