My Internet IP address and ISP Gateway Address in two different networks

I'm living with a few relatives right now and we just happen to be sharing an internet connection. However, it's been down for the past three days and when we called to ask why they agreed to send someone out to take a look at the lines, but my cousin ( whose room houses the cable modem ) instructed me to remove the router I had installed to share the connection because the ISP doesn't know about it.

That got me thinking, can an ISP forbid you from sharing an internet connection? Are there mechanisms in place to auto-disconnect people who are found to be sharing internet connections? I always believed that they couldn't, because the only way around that when there are a group of people that need internet access living in the same house is to have (and pay for) separate connections for each of them.

Without even knowing anything about jurisdictional matters, or the name of your ISP, I think the following general principle should apply:

If the terms and conditions you agreed to when signing up with the ISP, said 'no sharing of internet connections' then you shouldn't do it.

And this was one of the conditions in the early days of the Internet, here where I live, but my current multi-port router was provided by my ISP, so sharing is now condoned, maybe even encouraged.

The difference might be that connections here tend to be broadband, and need only one ADSL line. I don't know about your situation.

I guess your cousin just wanted to avoid the ISP people from seeing the router path that would indicate the connection was shared.

Some ISPs 'suggest' that the connection should not be shared.
However, this is easier said then done (enforced).
Setting up a router can easily let you share the connection and will not let the ISP from noticing the difference.

But, it is not impossible to know that you are sharing the connection (if the ISP decided to check you out -- audit would be the word here). I think it would be a lot easier than the the government of some country trying to break into an encrypted communication.

Detecting connection-sharing boils down to analysis of the connections seen from your end by the ISP (no need to look at the data, just the way connections are being setup).

The reason they would not bother doing this will probably be similar to the reason most people do not get audited for taxes by their governments :-)

If I were the ISP -- my bottom line would be, its not worth it.

Most ISPs nowadays provide wireless routers that an entire family can use.

Unless the conditions of sale clearly state otherwise (which would astound me), what you buy with the line is the bandwidth, so you're totally at liberty to use the line you rented as you see fit.

Just be careful, because some ISPs also impose a monthly quota on downloaded bytes.

It all comes down to the agreement you accepted when ordering their connection. If the ISP demands you to accept their terms of service, it might include not sharing a connection.

HOWEVER, you can easily share a connection without your ISP being able to do anyting about it. It would be the first time ever they'd get a search warrant for that.

One decent router which can clone your registered MAC address will do.

The ISP can impose whatever restrictions they like on the service they supply, within the bounds of whatever laws your area has that govern un-fair contracts. Most ISP's allow for as many devices in your household as you want. So long as you stay within their bandwidth limits. They also normally prohibit sharing the connection with other households. Obviously because they want each house to be paying. However, alot of ISP's won't SUPPORT a shared connection. So if you want their tech support to help, you need to demonstrate the problem with a single PC connected using the modem that your ISP has supplied. Things are improving in the UK now with more ISPs supplying a router with the package and they support that router,although they often won't (or can't) help if you have changed the router.

I'm not saying that the ISPs should do more, mostly these are sensible troubleshooting steps.