Linux Server Security, Second Edition

This is the Title of the Book, eMatter Edition

Copyright © 2007 O’Reilly & Associates, Inc. All rights reserved.

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Chapter 10

CHAPTER 10

Securing Web Servers

You’ve hardened your server from the bottom up, with an external firewall protect-

ing your DMZ, a local firewall blocking ports, and all the latest patches applied to

your operating system. Your fortress is impregnable. But then you blast a hole

straight through all these walls to a port on your server. Then you let anyone in the

world wander in and run programs on your server, using their own input. You’ve lost

touch with reality—and/or you’re a web administrator.

The Web continues to grow, and security problems follow. As firewalls and security

tools improve, attacks move up the food chain, particularly toward web applica-

tions. In this chapter, I assume that you are hosting web servers and are responsible

for their security. Although the examples discuss servers exposed to the Internet,

most of the discussion applies to intranets and extranets as well. The platform is still

LAMP: Linux, Apache, MySQL, PHP (and Perl). I’ll talk about A, M,andP here.

MySQL database server security is covered in Chapter 8, but database access from

Perl and PHP is discussed here. We’ll see how to protect your whole web environ-

ment—server, content, applications—and keep the weasels out of your web house.

Web Security

Bad things happen to good servers. Malice ...