What software are there to track which websites a wireless router user has visited?

warlord: What software are there to track which websites a wireless router user has visited?
I am looking for software that can track the websites and webpages a user has visited. For example, I am operating a wireless router that connects 5-7 users to the Internet. I am interested in what are these people are doing with my wireless service, as in are they abusing the wireless service that I am providing to them?

I am interested in how much time they are spending on the Internet, what websites they have visited or the webpages they are surfing and if they are downloading materials.

I know that such software are available on the open market but so far, I’m not sure where to find them. I am hoping for examples of such software that I can use.

Furthermore, I also wonder if the users on my wireless router can block such tracking software or If they can tack my attempts to follow them or if they will be aware if I am using such software to track them.

I undertsand that large networks and corporations routinely use such software. Are such software very expensive?

Answers and Views:

Answer by tj
One solution is to setup a transparent proxy.
https://www.squid-cache.org/
This can be done as to not interfere with access but can provide all sorts of data including every web access or you can restrict certain sites if you really want to. There are several add-ons that have been done for squid to provide reporting from the logs that it can keep. A side benefit is that using caching you can maximize bandwidth and make browsing effectively quicker for sites that are visited frequently or by multiple users.
This is basically a free solution. Any, say, old pentium machine with decent network cards, a fair amount of memory, HD space and Linux loaded on it can handle this.
You could also use something like tcpdump (a packet capture utility) which can monitor *all* traffic going through the network. This too is a free program.
https://en.wikipedia.org/wiki/Tcpdump
https://www.tcpdump.org/

The average user would have no idea if you were using any type of ‘tracking’ method. And all but the most knowledgable would be aware of certain methods (eg tcpdump can be quite difficult to determine if it is being used depending on how it is used). While it would be pretty easy for someone to realize that they are going through a proxy (eg. a random error with the proxy accessing a page) this can be excused as being in place for the speed benefit.

Many corporations probably use some commercial software, mainly because they have a budget and don’t care so much about cost as they do prettiness and nifty charts and reports that a program can make for them with ease. There is plenty of open source software that can do just as much. For more possibilities do a search on freshmeat or sourceforge.