Apache User Authentication

A guide to setting up user authentication for the Apache web server running on Linux, using the plaintext file method.
Potential Slowdowns

Using a plaintext file to maintain user names and passwords is easy and straightforward. Nevertheless, employing this method with a large number of users causes a lot of processing at the server side to search the file for the credentials in question; this adds to the server load. Moreover, processing has to be done for every request inside the protected area; even though the user only enters their password once, the server has to re-authenticate them on every request due to the stateless nature of HTTP. Therefore, the server does not remember any information about a request once it has finished and must resend the user name and password on each request.

Faster Access

Much faster access is possible using DBM format files. This allows the server to do a very quick lookup of names, without having to read through a large text file. The slight drawback of this method is the complexity of managing DBM files as compared to managing plaintext files. There are various add-on modules which allow user information to be stored in databases. Aside from the DBM format (mod_auth_dbm), user and group lists can be stored in DB format files (mod_auth_db). Full databases can also be used such as mSQL (mod_auth_msql), Postgres95 (mod_auth_pg95) or any DBI-compatible database (mod_auth_dbi).

Security Issues

There are a couple of security considerations regarding the password files managed by htpasswd. First, files containing users' information such as /etc/httpd/users, should be outside the web space of the server—they must not be fetchable by a browser. Secondly, the use of the -b flag with htpasswd as shown in Figure 4, is discouraged since when used, the unencrypted password appears on the screen.


Authentication is vital and necessary for most web servers. Apache has proven its reliability, and has an excellent record of stable performance and trustworthy security. Using Apache's authentication features, we can combine a cost-effective way to secure our documents using the most popular web sever running on Linux.


email: ibrahim.haddad@lmc.ericsson.se

Ibrahim F. Haddad (ibrahim.haddad@lmc.ericsson.se) is a senior member of technical staff at Ericsson Research Canada based in Montréal. He researches distributed-object technologies and web servers performance at Concordia University as a D.Sc. Candidate. Ibrahim would like to take this opportunity to thank his parents for all their help and support, not to mention the countless sacrifices, in the last twenty-five years.