If somehow an intruder becomes aware of the IP address of my system:
- What information can he obtain from my system or about my network?
- What type of harm he can do to my system remotely?
If somehow an intruder becomes aware of the IP address of my system:
Anything, and yes I do mean it, between everything and nothing. Completely depending on the security of your system.
Directly, a port scan can give many technical informations and/or denial of service.
Indirectly, Whois database can give administrative informations which can be injected into Google to get other data potentially useful for intruders.
It depends on the configuration of your system. For example, if you had a wide open router and ISP, and had certain services running (VNC, Remote Desktop, Telnet, SSH, FTP, SFTP, etc.) and the attacker could guess the password (or the password was disabled), they would have full access to everything on your machine which your account has access to.
However, if you have a default router setup like your ISP gave you, and you don't enable any special services, then the IP is most likely worthless to an attacker unless there is a vulnerability in your operating system.