My neighbor asked me if I wanted to share his network with me. Internet access is a little more expensive here than I am used to in my country. Before saying yes I wanted to know if I had risks in sharing my internet with him. He keeps the box and I will only have the wi-fi, which is enough for me, but about the security I don't want him to look at my bank passwords or something like that. I don't know if it's more risky than public wi-fi, but if someone can give me an idea or maybe advice.
You are certainly adding risk though whether that is enough to worry about may be difficult to calculate.
- Is it against the terms and conditions of use of the ISP? You both could get cut off. Low to medium risk, relatively low impact.
- Will someone in their household do something illegal that you might end up on the hook for - because you cannot prove you were not complicit. Illegal file sharing, child pornography or something else. Medium risk, terrible impact.
- You will be relying on their router being secure - it may well be now but will it always be? Medium risk but potentially high impact.
- You will be using a wireless connection between houses, will anyone else create a rogue Wi-Fi hotspot that will intercept your connection? An unlikely issue generally but quite high impact.
I would estimate that the risks of all of that are far lower than public Wi-Fi but they are certainly nowhere near zero.
UPDATE: You could help mitigate some of these risks fairly readily. You could have a written and signed agreement for example. You could make sure your neighbours router created a VLAN and you could give them your own Wi-Fi access point so that your traffic was segmented from theirs.
I think it comes down to how much you trust this person. Public Wifi can be dangerous because attackers can use things like packet sniffers to detect traffic and obtain passwords and other identifying information over the same network they're in. This guy could theoretically do the same without you knowing it. Depending on the network settings you have on your current system, he could have access to certain shares or drives you have created on your system that may be set to be accessible in a shared setup like that. That goes for anything you connect to the network too.
If you trust him, you have nothing to worry about. If you have any reservations, I'd probably hold off.