Another recent question was a repeat of one I’ve answered a number of times. The person wanted to know if they should get a router when they get a cable broadband Internet service.
My answer, as always, is "Yes!"
Your cable company might tell you that you only need a router if you’re going to have a home network — or they’ll try to sell you on the horrible idea of buying a hub and multiple IP addresses from them — expensive and stupid!.
Remember that these are the same kind of people that used to tell us that we don’t need a firewall because they had one.
You DO need a router, even if you only have one computer that you’re connecting.
Think of it this way. Do you need a lock on your door?
The router functions to lock the Internet away from your computer. If your computer asks for something from the Internet, it asks the router. The router asks the IP address on the Internet.
The server at the other end can respond, and the router will know to which computer to route the response. But, no computer on the Internet side can INITIATE communications with your computer.
Your compute would not have an IP address on the Internet. It’s address would be on the local home network (even if that network is nothing but one router and one computer). The WAN port of the router is the only thing that has exposure to the Internet.
So, what’s the big protection if you’re already running a software firewall? The importance is that you simply are not accessible. Some of the Windows flaws have been such that Windows itself would be subverted before a firewall program ever had a chance to block an incoming connection. So, we prevent that incoming connection…
So, yes, you need a router. It’s a security issue.
See also: Hub or Router
You may also want to read the other networking articles linked from my Computer Tips page.