Static DHCP Offers Consistent Remote Access

You may not know this, but upgrading the near-legendary Linksys WRT54G series routers with free, often open-source firmware is one of the best bargains going. Replacement firmware typically offers a plethora of advanced router and firewall features rarely found on sub-$100 hardware.

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  1. Make a note of the pool of addresses the router uses when assigning dynamic IPs. Here, we see a pool of 100 addresses, beginning at 192.168.0.100 and ending at 192.168.0.200. It will be important later that your static DHCP address assignments fall outside this pool. (If you make any changes here, be sure to save your settings.)

  2. Go to the page Administration/Services. Here’s where the action is. Below the “Static Leases” heading, click the “Add” button to create a new DHCP entry field.

  3. Enter three values: the MAC address of your client machine’s network adapter, a host name for the machine, and the IP address you want it to be assigned. Choose any host name you like, such as “Webserver” or “gameserver”. Choose an IP address which follows the same pattern as those in your DHCP address pool (in our example, 192.168.0.x). Choose a number for x which is outside the address pool seen in step 3 (in our example, 201).

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You can find the MAC address for your network adapter in either Windows XP or Mac OS X with a few clicks.

Windows XP
Click Start/Settings/Control Panel/Network Connections and click the name of your network connection. Wired connections are typically named “Local Area Connection,” while wireless connections are called “Wireless Connection”. In the Status window, click Support, and in that window, click Details. Your MAC address is the series of hexadecimal pairs labeled “Physical Address”. Use colons rather than dashes to separate the pairs in the DD-WRT interface.

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Mac OS X
Go to the Dock/System Preferences/Network. Click the Ethernet tab. Your MAC address is labeled “Ethernet ID”.

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  1. With your MAC address, host name and chosen IP address entered into DD-WRT, be sure to click Save Settings at the bottom of the page. If you want to add another static DHCP entry, you must save your settings first, then click Add to create a new entry.

  2. If you like, add a port forwarding entry for your new static DHCP address. In our example, we set up a Web server on our client PC. Our Web server listens for traffic on the default port 80. But our ISP blocks incoming traffic to port 80, because they don’t want us running Web servers (ours is for private personal use, we totally swear). Go to Applications & Gaming/Port Forwarding in the DD-WRT menu. Click Add to create a new forwarding entry. We enter an identifier into the “Application” field, in this case, “Webserver”. The router will listen for traffic on port 8088, so that we can connect from outside without being blocked by the ISP. Our destination IP address is the static DHCP entry created in step 5, and our destination port is where our Web server is actually listening, port 80. Be sure to check Enable for this definition to take effect. And, of course, Save Settings.

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You are now, as they say in the new Taco Bell ads, which are vastly inferior to the ones with the talking Chihuahua, “good to go.” Even if you don’t run Web, game or other servers on your local machines, you never know when a stable, predictable IP address will come in handy.

Adapted from wi-fiplanet.com.

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