accessing computers behind routers over the internet

[doritoman]

I was wondering how exactly routers know which computers to direct what traffic to? I mean if four people are using myspace from the same router how come they don't see what the other person is doing on myspace?
thanks,
doritoman
edit: is this section for wireless networking only ?
if so my bad I didn't see the wireless sign on the index

[Goatboy]

I was wondering how exactly routers know which computers to direct what traffic to? I mean if four people are using myspace from the same router how come they don't see what the other person is doing on myspace?
thanks,
doritoman
edit: is this section for wireless networking only ?
if so my bad I didn't see the wireless sign on the index

Although the title of the forum says Wireless, this is for all networking. We aren't past cables yet =)

As for how routers work, here is a short summary:

-A packet of information is sent, containing the payload (actual info) and a header (routing info)
-The header contains info such as who sent the packet, where it is destined, etc.
-The router reads the header and determines where to send the packet

Think of the header as the address information on an envelope, and the payload as the letter inside.

Example:

Router - 192.168.1.1
Computer A - 192.168.1.101
Computer B - 192.168.1.102
Computer C - 192.168.1.103

Computer A wants to access MySpace, so it sends a packet through the router with "192.168.1.101" in the header as the "Return address" and "63.135.80.46" as the "Destination address" MySpace receives the packet, disassembles it into the header and payload, does some other magic stuff, and then sends a response back to the router with the original "Return address" as the new "Destination address" The Router then sends the response packet back to Computer A.

If Computer B wants to talk to Computer C, it still must use the router. The big difference here is that the packet is not going all over the Internet; it simply goes from B to router to C. The router has a table it consults of the IP addresses of each computer and where it is located on the network. It uses this table to determine where to send each packet.

In each case, the router is smart enough to send the data only to where it needs to go. Imagine if every packet sent or received went to each computer. In a network of 3 computers, this may not be a problem. But if 100 computers are all getting 100x more info than they need, this would crash the network.

That is the way oversimplified version. I left out a lot of technical details so you can just get the concept. Now, as for your MySpace question, I am a little confused as to what you are asking. A router does not allow you to see what other people are doing on your network, at least not directly. You can't (easily) see their screens, for example. You could, however, monitor the inbound and outbound traffic.

If you want a more in-depth view, http://www.howstuffworks.com has some great tutorials. In this example, I mainly used internal IP addresses, which are addresses only from within your network. Your router does not look like "192.168.1.1" to the Internet. It may look something like "175.49.66.129"

[r0y4lty]

Wow explanation Goatboy, I give you thumbs up helped me out to understand routers better

[Goatboy]

Wow explanation Goatboy, I give you thumbs up helped me out to understand routers better

Glad I can help. That's what I'm here for.