Difference between revisions of "Disabling the use of weak DH keys in Zimbra Collaboration mailboxd"
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=How to fix Mozilla Firefox error - ssl error weak server ephemeral dh key= | =How to fix Mozilla Firefox error - ssl error weak server ephemeral dh key= | ||
==Purpose== | ==Purpose== | ||
| − | Since the 30th of June of 2015, Mozilla Firefox doesn't support | + | Since the 30th of June of 2015, Mozilla Firefox doesn't support connections to a server with weak DH ciphers anymore, as per [https://www.mozilla.org/en-US/firefox/39.0/releasenotes/ Mozilla Release Notes]: |
* Removed support for insecure SSLv3 for network communications | * Removed support for insecure SSLv3 for network communications | ||
* Disable use of RC4 except for temporarily whitelisted hosts | * Disable use of RC4 except for temporarily whitelisted hosts | ||
Revision as of 15:01, 6 July 2015
- This article is a Work in Progress, and may be unfinished or missing sections.
 Article Information |
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| This article applies to the following ZCS versions. |
How to fix Mozilla Firefox error - ssl error weak server ephemeral dh key
Purpose
Since the 30th of June of 2015, Mozilla Firefox doesn't support connections to a server with weak DH ciphers anymore, as per Mozilla Release Notes:
- Removed support for insecure SSLv3 for network communications
- Disable use of RC4 except for temporarily whitelisted hosts
You will see the next error message trying to connect a Zimbra Collaboration 7.x or previous versions:
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.
Resolution
You have different steps to resolve the issue:
- 1.- The first, and recommended, one is upgrade to a Supported Zimbra Collaboration version, 8.x, as Zimbra Collaboration 7.x is EOL since March this year.
If you want to Upgrade, we had an special Webinar that will help you with the process - https://community.zimbra.com/collaboration/f/1884/t/1139230
- 2.- The second one is disable the new introduced option in Mozilla Firefox, you need to do it in each Web Browser that uses your Zimbra Collaboration Server:
Type about:config in your Firefox web browser, in the address bar. Be careful as you can break your Firefox Configuration easier. Change the next settings with the next values:
security.ssl3.dhe_rsa_aes_128_sha=false security.ssl3.dhe_rsa_aes_256_sha=false
- 3.- Not recommended, you can set the zmtlsctl to both, to enable HTTP traffic to your server, users will be able to connect using Firefox 39, previous or above versions using HTTP.
Like zimbra user:
zmtlsctl both zmcontrol restart
Additional Content
- Mozilla Firefox Release Notes for the version 39 - https://www.mozilla.org/en-US/firefox/39.0/releasenotes/
- Mozilla Firefox Bugzilla 587407 about the change - https://bugzilla.mozilla.org/show_bug.cgi?id=587407
