IP number tracking

[mamainmichigan]

I am so dumb with this stuff so I apologize if this is a stupid question. But I run a forum. It is a very small forum with less than two hundred members. Today I looked and noticed that I had nine members registered with the exact same IP number. I don't really understand how this works. They are with AOL. Am I being paranoid or does it seem highly unlikely that there would be nine members out of about 150 with the exact same IP number? I don't want to make assumptions but I am very suspicous. How do you track IP #s. I use invision board and I know it has cookies enabled but I haven't got a clue how cookies work. I have been trying to figure this out myself by searching but thus far I am still confused. Please help.

[ronburk]

I looked and noticed that I had nine members registered with the exact same IP number. I don't really understand how this works.

Works roughly like this. There are more things that want to use TCP/IP than there are IP addresses. Some of these things have to share. I'm not sure you really want any more technical detail than that.

Slightly more technical: a connection via TCP/IP is not identified merely by two IP addresses (the client and the server). If it were, then it would indeed be mystifying how two different AOL users could talk to you via the same client IP address. In fact, however, a TCP/IP connection also requires a source port and destination port to distinguish it from all other connections. You might think of port numbers as "channels", and in a TCP/IP connection, each side knows what channel the other side is using to transmit. There can be a whole lot of channels for a single pair of IP addresses that are talking (about 64,000).

I can connect to your web server because I can translate your DNS name (www.whatever.com) to an IP address AND I know that web servers generally listen on port 80. When I "connect" to your IP address on port 80, I transmit both my IP address and the "ephemeral" port that I decided to use for this conversation. If it accepts my request to connect, your web server will also pick an ephemeral port that it sends back to me to use in future packets.

If you were able to look at the packets going to your web server in detail, you would see that IE clients often have two different connections open to your web server at the same time -- using two different sets of ephemeral ports. Just as my client browser can open two different connections with only one client IP address, so the AOL proxy machines can use a single IP address to proxy requests from a large number of internal AOL clients.

How do you track IP #s. I use invision board and I know it has cookies enabled but I haven't got a clue how cookies work. I have been trying to figure this out myself by searching but thus far I am still confused.

I cannot tell what you actually want to do. If you want to count IP addresses, just take the ol' weblog and count'em up (but why?). Perhaps you want to count "unique visitors", even though there is no foolproof method for doing so. You could use cookies for this, which of course will not count people who have cookies disabled. URL rewriting (such as Amazon uses) is probably the method that works in the largest percentage of cases. How you do any of these will depend on what facilities you have available. Sounds like you're using a particular package that presumably has a forum somehwere dedicated to supporting it.