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What kind of device is the router?

In most home networks there are several computers, printers and there is a router. But what is a router and what is its functionality?

In most small networks like a home network it is a small hardware device. In a larger network like in a company it can also be software on a server. Here we explain it in form of a hardware device which is often used at home.

It is a device which connects two or more networks together. For example in a home situation it connects a home network to the internet. You can see it as a connecting device for data packets from the one network to the other network.

How to use a router?

Here you see a home network with 2 computers, a laptop and a printer connected to a computer connected to each other by the router. This router is the device which connects the computers in the network to the internet.

Routers as shown in the picture above have mostly also a DHCP-server in it. A DHCP server means that it can assign IP-addresses to every computer or other devices such as network printers etc. so they can communicate with each other over the TCP/IP protocol.

A DHCP server automatically assigns IP-addresses to every computer which is connected to the router which have made the setting to ‘Obtain an IP address automatically’ in the network connection.
Also the routers have often a firewall function in it to protect the home network against attacks from the internet.

I will discuss one which is often used in a home network and I will discuss about its functionality. This one has almost every functionality that others have also. So read the information below and you will understand how they work, what the functionalities are and the settings you can make in them.

What kind of device is the router?

The one I will discuss is a Wireless D-Link DSL router which is a popular home router for home or office use.

I will discuss one by one its functionalities so I hope you can understand what most can do. The functionalities this one, and many other routers, have are:

  • 4-port switch
  • Router function
  • Wireless network available
  • Speed up to 11 Mbps over the Wireless network using 2,4 Ghz Band
  • NAT with VPN pass through (Network Access Translation)
  • MAC filtering
  • IP filtering
  • URL blocking
  • Domain blocking
  • Encryption

Now what does all above mean? Below I will explain it to you.

4-port switch
This means that this device can connect up to 4 computers over the Local Area Network (LAN). The switch function means that it can switch between different network speeds. This router (as shown above) can work with network speeds up to 100 Mbps. The switch function in it can switch between speeds from 10 Mbps and 100 Mbps. For example if you have 2 computers. One has a network card with a maximum speed of 10 Mbps and the other computer has a network card of 100 Mbps. Now the switch function can handle both speeds. A hub for example cannot switch between different speeds. So a switch is a bit ‘smarter’ then a hub.

Router function
This function is the main function of this device, that’s why it is called a router.It searches, to find the right outgoing port, for the destination address of the packet which is coming in, in the routing table. A routing table consists of a table with IP addresses or grouped IP addresses (like a subnet), and the next accessory junction.When the destination address routable is (so if it exists in the routing table), the router will use the next junction to determine the outgoing port. Now the incoming IP-packet will be send to the outgoing port.

Wireless network
If a router has a wireless interface it is often called a wireless router. This means you can connect to it using a wireless network interface. Further it works the same as you connect to it over a cable which is connected to it but now wireless.The antenna on the router has the functionality to send and receive packets over the wireless network and you can for example go and sit outside the house and you can access the internet over the wireless network via your router.

What kind of device is the router?

Speed
There is a difference of speed between the local area network (cable) and the wireless network. A connection over a network cable is faster then the wireless network. This one (and many others) has over the LAN a speed of 100 Mbps (Mega bit per second) connection and over the wireless connection a speed of 11 Mbps. The speed over the wireless network is often also 54 Mbps. The speed of the connection depends on the device.

NAT (Network Access Translation) with VPN pass through
NAT means Network Access Translation. This means the translation of IP addresses from one series to the other.
This function is often used in home networks. This is often used to connect home networks to the internet. Using this function you can connect a complete network to the internet by using just 1 public IP address. For example:
At home you have IP address like 175.18.x.x. Now the router, which connects the two networks together, translates the local addresses to a valid public address and vice versa.

VPN pass through means that this one can handle VPN connections. A VPN connection is a Virtual Private Network which is a private network over the public one. It’s done with encryption. Your data is encapsulated and secure in transit, this creates a virtual tunnel to connect for example to a private network over the internet such as a company network.So using this router you can set up a VPN connection.

MAC Filtering
MAC (Media Access Control) filtering means that you can filter MAC addresses which are trying to access your wireless network. You enter the MAC addresses you want to have access to your network in the MAC Filter Access Control list. The listed MAC addresses have access to the wireless network and other MAC addresses don’t. So if someone is trying to access you wireless network from the outside he can’t come in because the router compares the MAC address of the computer which is trying to access the network with the MAC addresses in the Access Control list and these are not corresponding so he doesn’t have access to the network.

So you can enter every MAC address of the Wireless network cards of computers in de network you want to have access to the network.

IP filtering
IP filtering works just like MAC filtering. The only difference is that the router now filters on IP address instead of the MAC address. Using IP filtering you can for example deny some IP addresses in the network to have access to the internet.

URL blocking
URL means Uniform Resource Locator. A URL is location of an information resource like a website, a file or a picture on the internet. An example of a URL is http://www.google.com.A URL is not only a http request but it can also be:

  • FTP
  • TFTP
  • IRC
  • HTTPS (secured http)

So what is now URL blocking? URL blocking means that you can block some URL’s so that users in your network can’t go to that URL. In this router you can enter a list of words you want to block. For example: You are in a situation at home and you have children. You don’t want that they can visit pornographic or discriminating websites. You can enter the words in the list or the URL’s you want to block, like ‘sex’, ‘porn’, ‘Nazi’, etc.So now if you want to visit the website http://www.sex.com, this will be blocked by the router and the website can not be shown. The same works for something like http://www.ilikeporn.com, because here is also the word ‘porn’ in the URL and this will be blocked.

Using URL blocking you can make sure your children or someone else in the network can not visit such websites.

Domain blocking
Domain blocking means that you can block an entire domain. It works the same as URL blocking but the difference is that by URL blocking you can block URL’s with a specific word in the URL and by domain blocking you give up an entire domain like http://www.sex.com. This website is now unreachable.You can choose for the option to block every domain except the domains you entered in the ‘Permitted domains’ list or you can choose to allow every domain except the domains in the ‘Blocked domains’ list.

Encryption
encryption is the process of obscuring information to make it unreadable without special knowledge, sometimes referred to as scrambling.

Encryption can be used to ensure secrecy, but other techniques are still needed to make communications secure, particularly to verify the integrity and authenticity of a message; for example, a message authentication code (MAC) or digital signatures. Another consideration is protection against traffic analysis.

The encryption in this router means the WEP encryption of your wireless network. Using WEP encryption you can encrypt your wireless network to secure this network against people from the outside which are willing to try to access your network.WEP encryption is an encryption which can be set up as 64 bit or 128 bits and you can choose for hexadecimal or ASCII code.For 64 bit ASCII encryption you must enter a WEP key of 5 characters and for a 128 bit ASCII encryption you must enter a WEP key of 13 characters. So a 128 bit encryption is more secure then a 64 bit encryption.

In much routers you can also enter a pass phrase and the router generates a WEP key automatically.
If you use a WEP encryption and you are trying to connect to the wireless network you will be asked to enter the WEP key. Without this key you cannot access the network so someone outside the network who does not know the key can’t access your network.Of course you don’t want to enter the WEP key every time you want to connect to the wireless network, so you can enter this key on your computer at the particular wireless network and then you won’t be asked to enter the key every time.

To enter the key on your computer just follow the next steps.

How to store the encryption key on your computer?

Step 1:
Click Start -> (Settings) -> Control Panel -> Network Connections

Step 2:
Here you click right mouse button on your wireless network connection and you click ‘Properties’.

Step 3:
Here you click the ‘Wireless Networks’ tab.

Step 4:
In this screen you see your wireless network. Select your wireless network and click ‘Properties’.

Step 5:
Here you can choose which network authentication is being used and which data encryption. Here you choose the WEP encryption. At the ‘Network key’ box you enter the WEP key you entered in the router. After you set up all this you click the ‘Ok’ button.Now when you connect to your wireless network the router compares the WEP key in the router with the WEP key on the computer and if they match the connection will be established.