I recently upgraded a Splunk cluster from v6.5.2 to v7.0.1. There was one thing that wasn't covered in the release notes. After upgrading my first host (master node), I couldn't execute CLI commands. Splunk threw the following error:
$ splunk enable maintenance-mode
Couldn't complete HTTP request: error:14077410:SSL routines:SSL23_GET_SERVER_HELLO:sslv3 alert handshake failure
Splunk Support admitted that they have some SSL bugs in the new release, and that this was one of them. To workaround this, you can make the following edits in server.conf:
sslVersions = *,-ssl2
sslVersionsForClient = *,-ssl2
cipherSuite = TLSv1+HIGH:TLSv1.2+HIGH:@STRENGTH
Once this is done, restart Splunk and try the CLI again. You should be back in business.
I had to update server.conf on most of my Splunk server hosts (master node, search heads, deployers, deployment server, license master, etc.) but for some reason not on my indexers. I'm not sure why as both my indexers and search heads run the same OS and had the same OpenSSL package installed. Hopefully this helps anyone out there with a similar issue.