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LDAP authentication on the F5 BigIP without Access Policy Manager

Intro
I recently received revised guidelines for dmz best practices which mentioned a requirement to implement application-independent authentication using the F5 web application firewall. I had never heard of it and didn’t think it was possible without buying the very expensive APM license. They insisted it was possible and even easy to do. So I investigated and found they were right!

The details
This is a feature added around version 11.4.

On the F5, go to Local Traffic|Profiles|Authentication|Configurations and create a new configuration. Here you put in the essential LDAP information and give these settings a name such as myLDAP. I needed to set Login Attribute to cn. Then go to …Authentication|Profiles and create a new one. Set parent profile as LDAP and associate the configvuration myLDAP to it. Rule can be _sys_auth_ldap.

In the virtual server Properties tab look for the section Authentication Profiles. Pick the profile you created.

That’s it! Your virtual server now has application-independent authentication using your preferred LDAP source.

So far I only tested against an LDAP source that doesn’t require an ldap bind. But I did successfully test against an ldaps source (which runs on port 636 and encrypts the communication using SSL. I got that to work setting SSL to Enabled and essentially taking the other SSL-related default values.

Conclusion
We show how to implement application-independent authentication on an F5 BigIP which only has the local traffic manager (LTM) license. We used an LDAP directory for the authentication source. I believe a certificate mechanism would also have been possible. As it happens our LDAP source was not an Active Directory (AD) tree, but I believe it would be possible to use that as well. We also did not limit access to any specific group, but that is probably possible as well.

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