|Title||Fix "HTTP header authentication"|
|Checkmk Edition||Checkmk Raw Edition (CRE)|
|Compatibility||Incompatible - Manual interaction might be required|
The HTTP header authentication can be enabled in the Global Settings using the option "Authenticate users by incoming HTTP requests". In case you do not use this authentication method, you are not affected by this issue.
It is mostly used in some reverse proxy setups where the Checkmk apache is located behind an authentication service. The authentication service only tells Checkmk the authenticated username and the user interfaces allows the user to enter without further authentication.
The user name is handed over as HTTP header with each HTTP request to the site apache and forwarded to the GUI.
With Checkmk 1.5 or older in connection with apache 2.4 and Checkmk 1.6 with all apache versions this feature can not be used anymore using HTTP header variables containing other characters than A-z, a-z, 0-9 and -. For example X-Remote-User is still working, while REMOTE_USER (which uses the not allowed _) is not working anymore.
This 1.6.0b3 release fixes an issue in this header variable processing and changes the default setting in the GUI to X-Remote-User.
If you configured this before with 1.5, you will have to check your configuration and change the HTTP header variable in the reverse proxy and Checkmk configuration to make it work with the new variable syntax.