Hi, So I have to track or get information for someone i sent emails with on Gmail. The only IP's I can find are: 10.163.168.149 157.55.2.9 I can track the last one but I'm not sure if it's his. He should be living in the Netherlands. I can't track the first one, can anyone help me with that? Would really appreciate it.
You can't track the first one because that's ot a public IP-address. It's an internal one, most likely from Gmail itself. The whole 192.x.x.x and 10.x.x.x-series are internal (not for public use). So no, it's not trackable. Tracking IPs are usually useless anyway, since they change often (most IP-addresses not in use by actual websites and/or login-services are dynamic, and change over time). If you have a problem, report it to the police, have them do a forensic investigation (or, rather, most likely, have them say "sorry, we can't help you").
To add to what PoPSiCLe said, usually forensics will fall short even if they try to help you. Anonymous VPNs (Virtual Private Networks), Tor Browser, and Proxychains do a fairly decent job of making tracking people a pain in the ass (not impossible, by any means, but a pain). I mean with linux I can be on a VPN, using proxychains on the Tor Browser. In addition, it becomes even harder if the individual filters through a proxy that is hosted in a country that doesn't give jurisdiction to your country. In the US, it's common practice for hackers to use proxies from china and russia, as both of them tend not to want to give information to the US on a good day.
Public IPs: Any IP-address not starting with 10.0.0.x, 192.168.x.x,172.16.x.x - 172.32.x.x - those are the private ones, which are NOT public, and not trackable - they are used inside a network using NAT (Network Address Translation), and will not be able to be used on the public internet. They are strictly for use inside private networks.