Caution

Do not use /etc/passwd as a user list for authentication. When you're using Basic Authentication, passwords and usernames are sent as base64-encoded text from the client to the serverwhich is just as readable as plain text. The username and password are included in each request that is sent to the server. So, anyone who might be snooping on Net traffic would be able to get this information!

To create a user file for Apache, use the htpasswd command. This is included with the Apache package. If you installed using the packages, it is in /usr/bin. Running htpasswd without any options produces the following output:

Usage:

htpasswd [-cmdps] passwordfile username htpasswd -b[cmdps] passwordfile username password htpasswd -n[mdps] username htpasswd -nb[mdps] username password -c Create a new file.

-n Don't update file; display results on stdout. -m Force MD5 encryption of the password. -d Force CRYPT encryption of the password (default). -p Do not encrypt the password (plaintext). -s Force SHA encryption of the password.

-b Use the password from the command line rather than prompting for it. -D Delete the specified user. On Windows, TPF and NetWare systems the '-m' flag is used by default. On all other systems, the '-p' flag will probably not work.

As you can see, it isn't a very difficult command to use. For example, to create a new user file named gnulixusers with a user named wsb, you need to do something like this:

sudo htpasswd -c gnulixusers wsb

You would then be prompted for a password for the user. To add more users, you would repeat the same procedure, only omitting the -c flag.

You can also create user group files. The format of these files is similar to that of /etc/groups. On each line, enter the group name, followed by a colon, and then list all users, with each user separated by spaces. For example, an entry in a user group file might look like this:

gnulixusers: wsb pgj jp ajje nadia rkr hak

Now that you know how to create a user file, it's time to look at how Apache might use this to protect web resources.

To point Apache to the user file, use the AuthuserFile directive. AuthuserFile takes the file path to the user file as its parameter. If the file path is not absolutethat is, beginning with a /it is assumed that the path is relative to the serverRoot. Using the AuthGroupFile directive, you can specify a group file in the same manner.

Next, use the AuthType directive to set the type of authentication to be used for this resource. Here, the type is set to Basic.

Now you need to decide to which realm the resource will belong. Realms are used to group different resources that will share the same users for authorization. A realm can consist of just about any string. The realm is shown in the Authentication dialog box on the user's web browser. Therefore, you should set the realm string to something informative. The realm is defined with the AuthName directive.

Finally, state which type of user is authorized to use the resource. You do this with the require directive. The three ways to use this directive are as follows:

• If you specify valid-user as an option, any user in the user file is allowed to access the resource (that is, provided she also enters the correct password).

• You can specify a list of users who are allowed access with the users option.

• You can specify a list of groups with the group option. Entries in the group list, as well as the user list, are separated by a space.

Returning to the server-status example you saw earlier, instead of letting users access the serverstatus resource based on hostname, you can require the users to be authenticated to access the resource. You can do so with the following entry in the configuration file:

<Location /server-status>

SetHandler server-status AuthType Basic AuthName "Server status" AuthuserFile "gnulixusers" Require valid-user </Location>

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