I've recently received a spam email that links to a website of legally doubtful content. How can I find out the Internet provider for the site, such that I can complain about the site? The whois-service gives some information, but the data seems to be about the domain registration, not the actual hosting provider or ISP. Is there some other service where I can find out who to complain to? Or am I just reading the whois output wrong?
The question is a bit tricky. Whois is normally a good place to start as it gives you a feel for the site, including the nameservers which, if often, but not always give you a hint about the hosting provider.
In order to work out where a site is located, you need to get its IP address. This is as easy as doing a "ping" to the site. Even better, if you use traceroute it will show you all the hops between your computer and that site - and usually the hops immediately before will give you a clue of their ISP's router. Importantly, using traceroute will do a reverse lookup on the domains and this will help you work out who their ISP is. You can then google the results to try and find a contact detail for their domain name.
Another technique might be to look and see how mail is handled for the site, and see if there is a link (again, not always). To do this you need to do a DNS lookup for the MX record for the site. (Googling "MX Lookup") should help you come up with a tool for this. If they are farming their mail out to an ISP, you should be able to do a WHOIS to find more about the ISP and contact them.
Once you find out IP, you have to go to the right Organisation. Now ICAAN have designated IPv4 range to huge organisation like apnic.net (for asia pacific) and ripe.net (for europe region). You can WHOIS search and find out to which organisation does the IP belongs to? And Later you may contact to corresponding organisation. I hope they might help.