This iterates over the directories in /var/www and runs Apache for each one, each with it’s own config file.

One interesting thing you can do here is make the user’s Apache process “nice” to fellow processes:

“nice” changes priority for tasks waiting on CPU, while “ionice” changes the priority for tasks waiting on IO (for example disk reads and writes).

This can keep one busy or misbehaving server from interrupting other sites or important background tasks; alternatively, you could set one site to be highest-priority.

AnyHosting currently uses Ubuntu Server (LTS) on a Rimuhosting.com virtual host. Ubuntu is very easy to install and use as a desktop, but if you haven’t done administration purely from the command line then Server can be a bit daunting. There are excellent starter guides and forums on the Ubuntu website.

Services

The following external services are provided (description followed by Ubuntu package name) :

• web server – apache2
• SMTP(+SSL) email server – postfix
• IMAP/POP(+SSL) email server – courier
• FTP – proftpd

Additionally, there are some internal services running, which are not visible from the internet (blocked by the “iptables” firewall):

• Database – mysql
• Monitoring/auto-recovery service – monit
• Automatic installation of security updates – cron-apt
• Log monitoring and reporting – logwatch logcheck
• Append-only network backups – rsync

Security

All unused ports are blocked. Any connection attempts are logged and reported. FTP and email services authenticate against the database, so clients do not need system or shell accounts.

For shared hosting, Apache is configured to proxy to chrooted installs which users have access to (as discussed previously). This is not as secure as having a real separate VM or better yet a separate machine for each web hosting client, but therein lies the dilemma of low-cost shared hosting versus moderate-to-high priced dedicated hosting.

The primary goal is to protect legitimate users from eachother; protecting the system from unauthorized intrusion (and detecting such intrustion) probably deserves it’s own series of articles, however the last few services listed in the “Services” section above should give some clues.

UPDATE link to secure shared hosting on ubuntu server part 1