Is it reliable to use the IP address to identify a user on your website?

Question

Here is my situation. I am part of a project creating a P2P charity website, where users connect and can give money to one another. Because of the nature of the site, we kno

Answer 1

No, it is not reliable. Because:

1. Residential customers who aren't specifically paying for a static IP address will often see their addresses change frequently. I'm on AT&T DSL and I see my IP address change roughly twice per month on average
2. People legitimately sharing an internet connection, whether they're using different workstations in the same office with a T1 line, or they're all connected to the same Wi-fi hotspot at Starbucks, will all have the same IP address.
3. Related to the above, people who are mobile, such as people who use laptops to connect to Wi-fi at coffee shops, airports, hotels, etc, will have a different IP address for each location they visit.
4. Even people who stay in one place with a static IP address can spoof your system by using a proxy server or a proxy tool like Tor. This makes IP restrictions trivial to bypass.