After performing the last Cisco CallManager update we were unable to login into Cisco Call Manager 8.5 via the web interface. When we attempt to login we received the following message:
Secure Connection Failed An error occurred during a connection to YOUR IP. SSL received a weak ephemeral Diffie-Hellman key in Server Key Exchange handshake message.
(Error code: ssl_error_weak_server_ephemeral_dh_key)
The page you are trying to view cannot be shown because the authenticity of the received data could not be verified. * Please contact the website owners to inform them of this problem.
The Cause:
Since the 30th of June of 2015, Mozilla Firefox doesn't support connections to a server with weak Diffie-Hellman ciphers anymore (Mozilla Release Notes:)
The Resolution:
Perform at your own risk. Accidental adjustment may effect Firefox's performance. To fix type about:config in your Firefox web browser, in the address bar. Change the next settings with the next values:
security.ssl3.dhe_rsa_aes_128_sha=false
security.ssl3.dhe_rsa_aes_256_sha=false
The values should be true by default. Click on them to change to "false."
That's it! You should now be able to login to Cisco Call Manager.