pam_realm

If you're in need of a software tool that checks user names for specific attributes, then pam_realm may be just what you need. This tool checks to ensure user names are in the proper format of user@realm, where the realm is inputted as an argument. Should this check pass, the "@realm" part of the username is removed and control is passed to the next module.

Thankfully, pam_realm provides users with a number of helpful options to customize the tool to fit their needs. For instance, the debug option doesn't actually do anything at present, but may be useful in future updates or for those working to understand the tool's programming.

Another great option is realm=realm, which allows you to specify the realm you want to check usernames against. This is particularly helpful since usernames vary from realm to realm and this option ensures your username check is tailored to your specific use case.

pam_realm also includes the allowbare option, which allows you to broaden the scope of your username check by including usernames without the "@realm" portion. Meanwhile, the nostrip option can be helpful for those who need to check the format of a username without removing the "@realm" portion.

As an example, you might use pam_realm in the following way:

auth requisite pam_realm.so realm=mail.example.com
auth require pam_unix.so.

Overall, pam_realm is a solid tool for any software developer in need of user name checking functionality.