What exactly is a router?

[haqking]

I allways explain a router as a sound mixer in reverse,instead of mixing signals from several devices into one output,you have one input and several outputs. Except they are bidirectional !
If you only have one PC then you wont need a Router. Unless your into carpentry-but thats a different route.

eddie

Loads of people use a router with one PC. I would suspect a large majority of the readers of this forum are using or have only one PC connected to a router.

For the benefits of the firewall, NAT, logs etc.

You also dont "need" a router with more than one PC.

I cant believe this thread has got so complicated, good job nobody asked about Layer 3 switches, Bridges, hubs (active and passive), Netbios and IPX/SPX routing....LOL

I think it would be beneficial to alot of people to read up on the OSI layers and watch the net warrior video in my post number #4

[offgridguy]

The OP appears not to have been back to this thread for a few hours. A summary might be in order.

• A router is a device that supervises and controls traffic on your network. Its role is similar to to a telephone exchange, which manages connections between telephones.
• A modem is a device that allows you to transmit digital data across a medium, such as a phone line, that is better suited to analogue data. You don't normally need one to connect to your Local Area Network (LAN)
• A Network Interface Card (sometimes referred to as an NIC) is a device that lets you physically connect to a network, usually through a router
• A WiFi card is a form of NIC that uses radio signals instead of a wire to access a router

In the interests of brevity, this summary is somewhat simplified.

Nice factual explanation. Thanks.

[Zill]

...I cant believe this thread has got so complicated, good job nobody asked about Layer 3 switches, Bridges, hubs (active and passive), Netbios and IPX/SPX routing...

A good point!

My understanding is that a "typical" home router actually rolls up five main functions into one box.

1. DSL modem to connect to the phone line
2. NAT firewall to translate IP addresses
3. DHCP server to allocate LAN dynamic IP addresses
4. Hub to distribute signals via one or more ethernet ports
5. wifi access point

[OrangeVixen]

Nowadays some modems are having inbuilt router,

What is confusing me is that a couple of howtos on IP masquerading (NAT) have different references to "router". Some are saying it's a Linux with a modem, others are describing it to something similar to what you described.

I have one Linux with a ppp0 interface using dialup. I'm not sure where the "router" goes.

I also found references to "switch" and "hub", I need to connect computers within the LAN to the Linux box with the dialup so they can access the net too. The Linux box has an ethernet card (a eth0 interface)

Do I connect the Linux box's eithernet card to a router or is the Linux box "is" the router in this case? where does the switch and hub come in?

[OrangeVixen]

So a router is a device (dedicated device or a dedicated PC) which is used to connect multiple PC's or devices that can interact with each other over the local network and also share the internet connection.

Thanks, I think I am beginng to understand what a router is now.

Since I am using dialup (and no, seriously, I'm at my relative's place in the middle of no where, we're lucky to have telephone, power, water, and food), the Linux box is using dialup to connect to the net, hence I am able to post this.

There are two other computers (a Mac and a Windows box) I want connect to the net, the Linux box has a ethernet card and so do the other two computers (they all have one) so I guess in this case the Linux box IS the router?

If so, then all I need is a switch or hub to connect the other computers to the "router" which is the Linux box?

[Cheesemill]

If so, then all I need is a switch or hub to connect the other computers to the "router" which is the Linux box?

Sounds good to me.
You also have to set up your linux box as a router that provides NAT and DHCP (not essential but makes configuring the other machines a lot easier).

I've used this tutorial successfully plenty of times (in your case replace eth0 with the name of your dial up interface):
http://codeghar.wordpress.com/2012/0...d-dhcp-server/

[OrangeVixen]

Sounds good to me.
You also have to set up your linux box as a router that provides NAT and DHCP (not essential but makes configuring the other machines a lot easier).

Thanks so I just need to get a switch, I got the NAT part, but do I really need to set up DHCP?

I have /etc/resolv.conf set properly on my Linux box (the "router") to use the ISP's domain name servers, do my subnet computers (the Mac and the Windows box) need DHCP?

Btw, the tutorial I'm going by is https://help.ubuntu.com/community/In...nectionSharing (which got my confused about "routers" in the first place).

[Cheesemill]

DHCP is optional. If you don't use it it just means that you have to set up networking (IP address, netmask, gateway and DNS settings) on the other client machines manually instead of it being automatic.

[redmk2]

Thanks so I just need to get a switch, I got the NAT part, but do I really need to set up DHCP?

I have /etc/resolv.conf set properly on my Linux box (the "router") to use the ISP's domain name servers, do my subnet computers (the Mac and the Windows box) need DHCP?

Btw, the tutorial I'm going by is https://help.ubuntu.com/community/In...nectionSharing (which got my confused about "routers" in the first place).

It might be helpful to think of the Linux machine as a stack of services. The routing part handles the inter-networking of different IP networks (e.g. packet forwarding). The switch (or hub) handles the inter-connection of machines on THE SAME network. The other items are enhancements to IP networking in a single network (LAN).

If you think of you dial-up connection as the interface to the wider world (WAN) and the Ethernet connection as the interface to the local network, then the router is the machine that forwards (back and forth) the traffic from the LAN to the WAN and visa versa.

The NAT is just translating the IP addressing for the machines on the LAN to the single Ethernet interface IP address on the Linux machine. When the data traffic is flowing you need a source and a destination. NAT handles that in a router with LAN addressing.

DHCP just automates IP addressing as has been stated preciously.

[davidtrounce]

Possibly because many of the wireless Modems come with a router built in.