Apache HTTP Server Version 2.0

Authentication

• Introduction
• The prerequisites
• Getting it working
• Letting more than one person in
• Possible problems
• What other neat stuff can I do?
• More information

Authentication

Authentication is any process by which you verify that someone is who they claim they are. Authorization is any process by which someone is allowed to be where they want to go, or to have information that they want to have.

Introduction

If you have information on your web site that is sensitive or intended for only a small group of people, the techniques in this article will help you make sure that the people that see those pages are the people that you wanted to see them.

This article covers the "standard" way of protecting parts of your web site that most of you are going to use.

The prerequisites

The directives discussed in this article will need to go either in your main server configuration file (typically in a <Directory> section), or in per-directory configuration files (.htaccess files).

If you plan to use .htaccess files, you will need to have a server configuration that permits putting authentication directives in these files. This is done with the AllowOverride directive, which specifies which directives, if any, may be put in per-directory configuration files.

Since we're talking here about authentication, you will need an AllowOverride directive like the following:

    AllowOverride AuthConfig

Or, if you are just going to put the directives directly in your main server configuration file, you will of course need to have write permission to that file.

And you'll need to know a little bit about the directory structure of your server, in order to know where some files are kept. This should not be terribly difficult, and I'll try to make this clear when we come to that point.

Getting it working

Here's the basics of password protecting a directory on your server.

You'll need to create a password file. This file should be placed somewhere not accessible from the web. This is so that folks cannot download the password file. For example, if your documents are served out of /usr/local/apache/htdocs you might want to put the password file(s) in /usr/local/apache/passwd.

To create the file, use the htpasswd utility that came with Apache. This be located in the bin directory of wherever you installed Apache. To create the file, type:

        htpasswd -c /usr/local/apache/passwd/passwords rbowen

htpasswd will ask you for the password, and then ask you to type it again to confirm it:

        # htpasswd -c /usr/local/apache/passwd/passwords rbowen
        New password: mypassword
        Re-type new password: mypassword
        Adding password for user rbowen

If htpasswd is not in your path, of course you'll have to type the full path to the file to get it to run. On my server, it's located at /usr/local/apache/bin/htpasswd

Next, you'll need to configure the server to request a password and tell the server which users are allowed access. You can do this either by editing the httpd.conf file or using an .htaccess file. For example, if you wish to protect the directory /usr/local/apache/htdocs/secret, you can use the following directives, either placed in the file /usr/local/apache/htdocs/secret/.htaccess, or placed in httpd.conf inside a <Directory /usr/local/apache/apache/htdocs/secret> section.

        AuthType Basic
        AuthName "Restricted Files"
        AuthUserFile /usr/local/apache/passwd/passwords
        require user rbowen

Let's examine each of those directives individually. The AuthType directive selects that method that is used to authenticate the user. The most common method is Basic, and this is the method implemented by mod_auth. It is important to be aware, however, that Basic authentication sends the password from the client to the browser unencrypted. This method should therefore not be used for highly sensitive data. Apache supports one other authentication method: AuthType Digest. This method is implemented by mod_auth_digest and is much more secure. Only the most recent versions of clients are known to support Digest authentication.

The AuthName directive sets the Realm to be used in the authentication. The realm serves two major functions. First, the client often presents this information to the user as part of the password dialog box. Second, it is used by the client to determine what password to send for a given authenticated area. So, for example, once a client has authenticated in the "Restricted Files" area, it will automatically retry the same password for any area on the same server that is marked with the "Restricted Files" Realm. Therefore, you can prevent a user from being prompted more than once for a password by letting multiple restricted areas share the same realm. Of course, for security reasons, the client will always need to ask again for the password whenever the hostname of the server changes.

The AuthUserFile directive sets the path to the password file that we just created with htpasswd. If you have a large number of users, it can be quite slow to search through a plain text file to authenticate the user on each request. Apache also has the ability to store user information in fast database files. The mod_auth_dbm module provides the AuthDBMUserFile directive. These files can be created and manipulated with the dbmmanage program. Many other types of authentication options are available from third party modules in the Apache Modules Database.

Finally, the require directive provides the authorization part of the process by setting the user that is allowed to access this region of the server. In the next section, we discuss various ways to use the require directive.

Letting more than one person in

The directives above only let one person (specifically someone with a username of rbowen) into the directory. In most cases, you'll want to let more than one person in. This is where the AuthGroupFile comes in.

If you want to let more than one person in, you'll need to create a group file that associates group names with a list of users in that group. The format of this file is pretty simple, and you can create it with your favorite editor. The contents of the file will look like this:

        GroupName: rbowen dpitts sungo rshersey

That's just a list of the members of the group in a long line separated by spaces.

To add a user to your already existing password file, type:

        htpasswd /usr/local/apache/passwd/password dpitts

You'll get the same response as before, but it will be appended to the existing file, rather than creating a new file. (It's the -c that makes it create a new password file).

Now, you need to modify your .htaccess file to look like the following:

        AuthType Basic
        AuthName "By Invitation Only"
        AuthUserFile /usr/local/apache/passwd/passwords
        AuthGroupFile /usr/local/apache/passwd/groups
        require group GroupName

Now, anyone that is listed in the group GroupName, and has an entry in the password file, will be let in, if they type the correct password.

There's another way to let multiple users in that is less specific. Rather than creating a group file, you can just use the following directive:

        require valid-user

Using that rather than the require user rbowen line will allow anyone in that is listed in the password file, and who correctly enters their password. You can even emulate the group behavior here, by just keeping a separate password file for each group. The advantage of this approach is that Apache only has to check one file, rather than two. The disadvantage is that you have to maintain a bunch of password files, and remember to reference th right one HTTP/1.1 200 OK Date: Mon, 07 Jul 2025 05:20:58 GMT Server: Apache/2.0.42 (Win32) PHP/5.2.10 Content-Location: auth.html.en Vary: negotiate,accept-language,accept-charset TCN: choice Accept-Ranges: bytes Content-Length: 16019 Keep-Alive: timeout=15, max=99 Connection: Keep-Alive Content-Type: text/html; charset=ISO-8859-1 Content-Language: en

Apache HTTP Server Version 2.0

Authentication

• Introduction
• The prerequisites
• Getting it working
• Letting more than one person in
• Possible problems
• What other neat stuff can I do?
• More information

Authentication

Authentication is any process by which you verify that someone is who they claim they are. Authorization is any process by which someone is allowed to be where they want to go, or to have information that they want to have.

Introduction

If you have information on your web site that is sensitive or intended for only a small group of people, the techniques in this article will help you make sure that the people that see those pages are the people that you wanted to see them.

This article covers the "standard" way of protecting parts of your web site that most of you are going to use.

The prerequisites

The directives discussed in this article will need to go either in your main server configuration file (typically in a <