You can inspect the HTTP request headers being sent into Nexus Repository Manager.
This is especially helpful to prove that your reverse proxy is sending Nexus the correct header values.
Nexus request logging utilizes Logback Access and therefore the log lines printed inside the request.log can be customized by adjusting the PatternLayout.
The pattern can be changed to print additional inbound request headers. Once you change the pattern, restart repository manager for it to pick up the changes.
If a header is being sent to Nexus, it's value should display in the logs.
If a header is not being sent to Nexus a single dash ( - ) will display instead.
HTTP header names and therefore the header pattern names are case insensitive.
RUT Auth involves having a server sending a header to repository manager which contains a userid. The header name is configured inside Nexus in a RUT Auth capability.
Change the logback-access.xml pattern value so that the header with the userid is printed in the logs - here we use the example header name REMOTE_USER.
...and then save the file, and restart Nexus.
With this pattern, each line will print the value of the remote_user header at the end. If the request successfully mapped to a valid user, then the third field on each line ( %user ) will print the same userid.
If request log lines do not end in https ( and instead just - ), then the reverse proxy is not sending the expected X-forwarded-proto HTTP request header that Nexus needs if the reverse proxy is terminating a HTTPS connection.