Jenkins: Jenkins is fully up and running but no dashboard is presented

Question

I have installed jenkins-2.401.2-1.1.noarch.rpm and java-17-openjdk on an empty RedHat 8.8 server. After starting the Jenkins server I can connect with the browser to port 8080, I'm asked for the first time admin password from the file /var/lib/jenkins/secrets/initialAdminPassword and after providing this in the browser there are only three vertical small bars spinning up and down. The log file says only:

# tail /var/log/jenkins/jenkins.log
74565d94443f4ed08790bf86da7953fd

This may also be found at: /var/lib/jenkins/secrets/initialAdminPassword

*************************************************************
*************************************************************
*************************************************************

2023-07-24 11:45:26.217+0000 [id=34]    INFO    jenkins.InitReactorRunner$1#onAttained: Completed initialization
2023-07-24 11:45:26.228+0000 [id=25]    INFO    hudson.lifecycle.Lifecycle#onReady: Jenkins is fully up and running

Any ideas what I am missing or could have done wrong?

Answer 1

After a lot of debug and tcpdump tracing it was dicovered that the Jenkins server connects with the URL http://www.google.com/... something at Google with the only motivation to see that for the update of the plugins the Internet can be contacted. While the server for the latter was answering fine, the connect to Google did not worked which could be proved also with the following command:

openssl s_client -connect www.google.com:443

which hung for ever. The host in question is behind some paloalto firewall and there it is not enough to enable "ssl" passthrough, but also some kind of "App-ID google-base". After enabling this, all was fine.