Static DHCP Offers Consistent Remote Access
Open source router firmware such as DD-WRT does things the factory-installed stuff never offers. For example, you can give a computer the same IP address every time so you'll always have remote access.
by Aaron Weiss
By now, you probably know that 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.
DD-WRT, a free, open-source firmware coded and distributed by “BrainSlayer,” has emerged as one of the leading, most powerful and also user-friendly firmware replacements for the WRT54G series. DD-WRT is available for an increasingly wide range of routers besides the WRT54G, including models by Asus, Belkin, Buffalo Devices, Motorola and Siemens.
There are caveats to upgrading your router, and the process is not without risk, so beware. We'll assume you've got DD-WRT successfully installed, and forge ahead...
In this first detailed look at new features you can get from open source router firmware, prepare to be dazzled by the capabilities of... the Dynamic Host Configuration Protocol (DHCP).
Out of the box, most routers and PCs are designed to manage their IP addresses automatically. The PC, whether wired or wireless, requests an IP address and related network parameters from the router using the DHCP protocol. The router plucks an unused address from its pool of available addresses, hands it to the client, and everyone is smiling.
This process results in what is called a “dynamic IP address” – every time the PC connects to the router (on boot-up, for example, or wireless association), it is assigned a new IP address. The router may assign the same address it assigned in the previous session. Or it may not. You don’t know and, usually, you don’t care.
There are cases, though, when you want your client to receive a predictable, consistent IP address. The most common scenario is when you run a server on your client PC. Suppose you run a Web site on a PC at home, and you need access to this server from elsewhere – work, school, your laptop in the park. Your router “hides” your server from the outside world, which is normally a good thing for security. This is why a higher power invented Port Forwarding
Your router will allow you to forward traffic destined for a specified port to a specific machine. In its simplest form, you can configure your router to forward incoming traffic destined for port 80 – the default port number for Web traffic – to the IP address of the PC running your Web server.
What is your Web server PC’s IP address? If it receives its address automatically from the router – you don’t know for sure. It could change, and your port forwarding would become unreliable.
One solution is to manually assign your Web server its IP address and network parameters, rather than use DHCP. However, this may limit your ability to easily connect that machine to other networks — a more likely problem for laptops. If your ISP changes name servers on occasion, this could also break your manual network configuration.
Ideally, if you continue using DHCP on your client yet can rely on always receiving the same IP address, you’re having your cake and eating it, too. Which begs the question – why would you have a cake if you weren’t going to eat it? Isn’t that the purpose of cake?
Fortunately, DD-WRT makes it easy to create static DHCP addresses for your network. Combining the best of both worlds, a static DHCP address allows your clients to continue receiving their network parameters automatically, yet you know exactly which IP address will be assigned.
You can find the MAC address for your network adapter in either Windows XP or Mac OS X with a few clicks.
Mac OS X
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.
Article courtesy of Wi-Fi Planet.
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