XinCom Dual WAN Router Review

Networking 64 Page 3 of 13 Published by

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Intro to Networking 2

Back to the networking primer!
Along with IP addresses, there are also MAC addresses. MAC addresses can be referred to as physical addresses as they are usually only accessible on local networks (lets keep it simple eh), and few MAC addresses can be changed. In fact, MAC addresses are set by the manufacturer of the hardware and should be unique. Although MAC addresses are used heavily in routing, we will only cover them here for simple uses.

The first time you should have come across a MAC address (if you are on something like cable) is when you registered your modem. You would have had to tell a server somewhere (via an operator maybe) that this modem exists and requires service. With a router, you need to clone the MAC address of the modem for NAT to work properly. After that, the WAN side of the router needs to have its IP address set (usually automatically), which leaves the realm of MAC addressing so we stop there!

The next time you may see MAC addressing is when you are dealing with local machines. Like we discussed earlier, many routers have administration functions, for instance blocking access to the net for one or many computers. This is very easy to do, and in one form or another uses MAC addressing.

Every network card also has a MAC address, the router can control what access is allowed via these MAC addresses because every request must go through the router.

In a generic example, a router dishes out IP addresses to clients via a DHCP service (how ISPs work for 100% of dialup users). A simple use of MAC addressing, is to split the IP range up and assign the same IP address(es) to a / many selected PC(s). Whats the use of that I hear you ask. Well this means now, that if any ports need to be opened on the firewall, you can open the port to only one machine, and therefore not exposing anyone else on the network to this open port. Because you have made the machine(s) in question have the same address, you can be 100% sure that it is only those machines that you are distributing service to. This is also a handy reference because a MAC address is hard to remember, where as a 3 digit number is much easier in comparison. Only 3 digits because most routers only assign 253 IP addresses, e.g. 192.168.0.1 -> 192.168.0.253 so you only need to remember the last three octets.

Anyway, that is the basic set of networking that you really need for this review. Have a look at the networking section in our forums if you have any other questions, there is a few links for general information, or you can ask questions if you are still unsure of a few points.

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