I am going to offer web hosting soon using LxAdmin and I am wondering, what should I do to keep anyone from hacking it or anything.
1. Research Servers a little more carefully, you have totally over looked a large amount of cost - server administrator. 2. You will need to employ a server administrator to manage the server and its security needs. 3. IDS & Account Security will need to be implemented. 4. Security threats are a major concern when running a hosting business. 5. Security Insurance, can you afford it? If not, are you a limited liability company? if not, you need to be.
Basic Linux Security Guide - http://mysql-apache-php.com/basic-linux-security.htm (D)DOS Deflate - http://deflate.medialayer.com/ Suhosin - http://www.hardened-php.net/suhosin.127.html CSF (http://www.configserver.com/) is probably the #1 thing. This is a start. Good luck.
Don't forget off-site backups. Make sure that if something happens at least you can restore things. Also count on users asking for files back that they deleted themselves - of course you can charge for that.
the most important step would be DELAY your hosting offer until YOU KNOW security else you are a walking liability just waiting to happen there are plenty of hosts who care a sh.. about security and know even less learn first what you want to do before you do it as a host YOU are playing with the welfare and future of your customers then when you KNOW all follow the steps by SSANZ above