Wednesday, October 17, 2007

Manual initial configuration of a router (Part 1)

Many routers in the consumer and SOHO price range come with little documentation and a CD which you are supposed to use for the installation of the router: you simply insert the CD and the software on the CD will automatically guide you through the whole installation process.

Sometimes this does not work, though. For instance, you only have a Mac and the software on the CD is usually only for Windows. Sometimes the software is just not intelligent enough to figure out why it is not working and never succeeds.

However, there is no need to use this CD or the software on the CD to configure a standard router. Most routers (I think even all except Apple Airport Express/Extreme) have a web based configuration interface through which you can make all necessary adjustments to get the router running on your internet connection. You can access this interface with a normal browser like Firefox or Internet Explorer which has JavaScript enabled. (Please note that some software firewalls tend to block the JavaScript making the interface inoperable.)

The initial configuration of a router is fairly simple, in fact, with some pitfalls on the way (into which the CD software likes too fall, too, I think) which you can get around quickly if you properly guided. As quite often people need at some point access to the web interface anyway to make more advanced setting there is no reason why you should not start with that right from the beginning and configure your router yourself. That way, you know what you did, learn more about your router and its workings and thus may get full "control" of your router instead of relying on some software on some CD which does all those initial settings hidden from you in the background.

Thus, let's start now to do the basic configuration of your router. You'll check first what kind of modem you have and a few settings on your computer and how it establishes its internet connection at the moment. Then you'll set up the internet connection on the router and check if it is working. If not, you can make a few tests and changes to find out why it is not working and how to fix it. Next, some basic security configurations of the router which are highly advisable during the initial setup in particular if you have a wireless router.

The modem connection
O.K. You have your router in the box. Before you hook it up, let's do some checks on your current internet connection and your modem. Connect your computer to the modem and make sure you have a working internet connection. Please note that you have to connect the computer with an ethernet cable and use the ethernet port on the modem. You cannot and should not test this with an USB connection if your modem has a USB port as well. Moreover, if your modem only has a USB port then this procedure will most likely not work for you. Most routers only connect with ethernet to the modem. You won't get your router running together with a USB modem. At least not the way it is supposed to be used and how the following procedure requires.

The ISP internet connection
To configure the internet connection correctly you should know the following things which you usually find in the documentation from your ISP. You may also call them to ask what of this applies to your internet connection. Later we'll double check most of these things thus it is not absolute necessary that you have this information at hand. However, it would help a lot if you did.
  • Internet connection type: Usually DHCP or PPPoE. Some providers use PPPoA instead of PPPoE. If it is PPPoA please make sure that your router does really support PPPoA. Many routers do not support PPPoA. An other rare option is a static IP address. If you have a static IP address please check with your ISP if this is really a simple static IP address to be used or if it is PPPoE with static IP address. Both are different. For the latter you still have to configure PPPoE as connection type. Be warned: some routers (most Linksys routers for instance) do not support PPPoE with a static IP address supplied on your side. You can only configure normal PPPoE and the ISP should assign your connection the static IP address automatically. But you cannot configure the static IP address with PPPoE connection on your router then. (The "Static IP" option as internet connection type is something different as it does not use PPPoE.)
  • If it is DHCP there is usually no further information needed to connect.
  • If it is PPPoE you usually need a user name and password. This may be the standard user name and password you use to access other resources at your ISP. Some ISPs require a special form for the username to be used on the internet connection. Check the documentation or ask your ISP.
  • PPPoA is similar to PPPoE.
  • Static IP (i.e. the option static IP without PPPoE) requires an IP address, subnet mask, default gateway IP address and one or more DNS server IP addresses.
  • PPPoE with static IP requires the same information as the previous static IP plus a user name and password.
Modem check
Now make the modem check. The first thing to take note of is whether those two IP addresses mentioned in the check are in fact identical or not. There is another router with network address translation (NAT) somewhere in the path between your computer and the internet. Most often, this is the modem itself which also has a router component built-in. If you live in an apartment building and use the internet connection supplied in the building it is probably somewhere in the building. If you use some other shared internet connection with others they probably already have a router somewhere.

If both addresses are not identical please take a note of the IP address and subnet mask. You must later know that to avoid IP address conflicts in case your router uses the same IP addresses you found on your computer now. If they are not equal you usually see IP addresses like 192.168.0.*, or 192.168.1.*, etc. with a subnet mask of If it is your modem which has those router functions as well you should consider putting the modem into "bridge" mode, i.e. turning off those router functions. That way your router will have a direct internet connection which is usually easier to use. But this is not covered in this blog entry. In the following configuration we leave the modem/router device you have just like it is.

If both are addresses are identical then your computer is directly connected to the internet. There are a few rare instances (I think some satellite modems) where this is not true but it should not matter here.

Some more information from ipconfig /all
If you have a printer you may consider to print out the full output of the "ipconfig /all" from the modem check before. There are a few things you can check to verify that the information collected above for your internet connection are in fact correct. First, take a look which ethernet adapter is the one which has the IP address on the computer. If it is the PPP adapter you use PPPoE or PPPoA on your internet connection (many DSL providers use PPPoE or PPPoA). You have entered the username and password when you have created the connection in Windows.

If it is the Local Area Connection or similar then you have a normal connection, i.e. without PPPoE or PPPoA. ipconfig shows whether you have DHCP enabled or not. If it is enabled then you have a normal DHCP internet connection (e.g. many cable TV ISPs use this). If DHCP is disabled you seem to have a static IP address on your computer.

Also take a note of the default gateway and DHCP server IP address. If you found two different IP addresses in the previous modem check then the default gateway IP address is the IP address of the next router on your path to the internet. In that case you will see identical IP addresses for the DHCP server and default gateway which means that the next router is also running a DHCP server.

Disconnect the internet connection
If you use PPPoE or PPPoA on the internet connection please disconnect the connection now. You can usually click on the network connection in the network connections control panel and click disconnect or choose disconnect from the right-click context menu. Disconnect the the network connection and once it shows that the disconnected state unplug the cable from the modem. Please also make sure that your computer does not automatically reconnect. Check in the internet options control panel. On the Connections tab you should have the choice whether or not to "dial" a connection. Please make sure you have "Never dial a connection" selected here.

For DHCP connections you may use the ipconfig command in a command prompt window like before. Enter "ipconfig /release *" to release all DHCP IP addresses. You have to be administrator on the computer to do this.

For static IP address connections (without PPPoE) you have to reconfigure the network adapter for DHCP as you need DHCP behind the router. You have to change that in the properties of the local area connection in the network connections control panel in the properties for the IP protocol element. Set IP address and DNS servers to be received automatically.

Now you have cleaned up your the internet connection.

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