[ Thanks to Kevin
Reichard for this link. ]
“The Apache Web server, like most if not all of the others in
common use today, lets you execute arbitrarily complex operations
through the use of CGI scripts. These can involve database lookups,
system administration functions, real-time control of machinery,
online payments, or almost anything else you can think of.”
“Ordinarily, all of these things occur in the context of the
user running the Apache server itself (typically nobody on Linux
systems). This is fine when you’re using a system that is owned and
used by a single entity…but what if you’re an ISP with multiple
companies being hosted on your system? Or an educational
institution with faculty who want to be able to execute their own
scripts? Either everything has to be accessible to the Apache
nobody user, or you have to run multiple instances of Apache on
multiple ports and IP addresses, one of each per user, with the
concomitant confusion of configuration files.”
“On the other hand, if the server is to be allowed to change
its identity, it needs to be done in a controlled manner, so that
the chance of compromising your system’s security is kept to a
minimum. (Remember, Apache is usually started as root and only
changes to nobody later!) The suexec (pronounced ‘SUE-ex-Ek’)
tool helps make this possible. It’s found in the src/support/
directory under your Apache source tree.”