How can someone hack into a Linux server ?

[ParanoiaUser]

Hi!

I have a debian linux VPS and i am wondering how would someone be able to hack into it , in what ways ?

I've asked a more knowledgeable friend and he said the only way someone would be able to get into my VPS is via FTP or SSH, are there some other ways someone can enter my machine ?

I have extremely strong passwords for all the accounts enabled and use fail2ban as well to ban SSH and FTP attackers.

I don't use apache,mysql,email accounts and update the server as often as possible.

Would appreciate if some of you guys could tell me, in what ways can my machine be compromised ?

Thanks.

[jpeps]

I'm extremely doubtful whether a server exists that can't potentially be compromised. Perhaps someone could intercept the password, or find some other way to open a port. The most secure system would be off the internet entirely.
If you're really concerned, you would need a staff that continuously monitors all activity.

[Karl Godt]

I have a debian linux VPS

Probably ask in debian forums ?