Protecting the Web server
By Stephen Mencik
SearchSecurity site expert Stephen Mencik offers his advice for securing a Web server in this Ask the Expert Q&A.
Q: How can we protect our Web server from external attack?
There are a number of things you can do to protect yourself against external attacks.
First, the Web server should have only those services running that are absolutely needed.
Second, the operating system and applications should all have the most recent security patches installed. The OS should be "hardened" as much as possible. A paper that is OpenBSD centric, but has some application to hardening all operating systems, can be found at
Third, it should sit behind a firewall that only allows those ports needed for operation. For example, if it is purely a Web server that does not need any access from the outside other than via http and https, then only ports 80 and 443 need to be open. However, if you are running a Web hosting company, your clients need to be able to upload files and more. So you'll probably need to enable the ports for FTP and Telnet. If you are combining this with e-mail services, you'll need to open the ports for POP and SMTP, or whatever protocols you use for mail. (For more information on ports, go to
Fourth, all form input should be validated by the script that handles the form. Buffer overflows are a favorite type of attack. A good reference for CGI script security is located at
Fifth, make use of audit logs. Use
where you can.
Sixth, make regular backups. Even the best security planning is not perfect. Someone still might find a way to break in. And even if there is no security break-in, you might lose a hard drive. So, you still want to have regular backups.
Essentially, you want to do everything you can think of to improve the security of the machine. You can do some Web searches for security information on your particular combination of OS and Web server application and find lots of good advice on the best things to do to make the server as secure as possible.
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Administrating Web servers, security and maintenance
By Eric Larson & Brian Stephens
Publisher Name: Prentice Hall
Date published: Dec. 1999
Cover Type: Soft Cover
This book is designed to provide individuals with the core skills needed to meet the demands of the Web development and Internet community. This user-friendly interactive text provides competency in three key skill areas: 1. Web Business Management, from financial issues to project management and marketing. 2. Content Management, including user interface, authoring languages, multimedia and graphics. 3. Technical Management involving administration, protocols, performance and security.