I recently setup VSFTPD on my personal server for sharing files over FTP. In the vsftpd.log file, i see hundreds of failed attempts to login with usernames like "adminitrator" , "adminitrator1", "adminitrator2", "adminitrator123" etc.

I am surprised because i just setup my FTP server and i thought no one would know about its existence. I did not communicate it to anyone that my FTP server exists.

I guess with port scanning tools, one would have found FTP port is open. However i wonder how one would have got my IP. 

* I downloaded a torrent file, would that expose my IP address?
* Is it quite common for the attacker to harvest the ip address from torrent trackers or some other service? Any idea how attacker gets IP address? (like for spamming - spambots are used to harvest the email ID)
* Any general pointers for a new comer to secure the server (books, videos, totorials, blogs etc)