Any luck in adding the host to security.tls.insecure_fallback_hosts ?

You can open the about:config page via the location/address bar and use its search bar to locate this pref:

• security.tls.insecure_fallback_hosts

You can double-click the line to modify the pref and add the full domain to the value of this pref. If there are already websites (domains) in this list then add a comma and the new domain (no spaces). There should only be domains separated by a comma in the Value column (example.com,www.example.com).

• https://developer.mozilla.org/en-US/Firefox/Releases/36/Site_Compatibility#Security
• https://developer.mozilla.org/en-US/Firefox/Releases/37/Site_Compatibility#Security
• https://developer.mozilla.org/en-US/Firefox/Releases/38/Site_Compatibility#Security

hi, thanks for the reply.

still no luck. do I have to restart firefox before trying again? I am using the nightly channel ( x64) could it be that the algorithm in question have been removed from the build?

You can check what cipher suite and TLS version is used in older Firefox versions and check if the used cipher suite prefs are still present in about:config. The list of available cipher suites gets shorter and shorter with each release as vulnerable suite are removed.

See also:

• SSleuth: https://addons.mozilla.org/firefox/addon/ssleuth

form what I see with this addon the server in question have a certificate with signature MD5/RSA with key of 512 bits only. another server with SHA/RSA and 1024 bits key is OK. I could not find in about config a way to set the minimum key length or to enable MD5.