I’ve just connected to the internet via an ethernet router in place of a usb modem. During the changeover Comodo popped up with a message saying “New LAN detected” along with options that I’m not knowledgable enough to understand:
“I would like to be fully accessible to other PCs on the network”
I’m using a single home computer and didn’t know what to do so I closed the window and carried on (I thought maybe every other user on the internet would have access to my files).
When you connect your PC to the internet via a router, you have actually created a local area network (LAN) consisting of your PC and the router. This is the new network that CIS detected. When you get this alert in future, you should select ALLOW and REMEMBER.
In laymans terms, a router is a computer in itself with two network cards, one inwards facing (this is the connection to your PC) and one outwards facing (this is the connection to the internet). When your PC requests a web page, your request is forwarded to the router. The router records your requests, changes the IP address from the strictly internal address of your PC to the public IP address assigned to the outward facing network card and sends the request out to the internet.
When the response is received on the outward facing network card, it is transferred to the internal network card and the IP address is changed back to the internal IP address of your PC. The response is then forwarded back to your PC. There is, naturally, a lot more to it than this.
In a nutshell, the router handles communications to and from your PC with its inwards facing network card. It also handles communications between itself and the internet (on your behalf). It sort of acts as an intermediary or filter between you and the internet.