Revision as of 21:34, 28 June 2014 by Thom (talk | contribs)

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This article applies to the following ZCS versions.

ZCS 8.0 Article ZCS 8.0

Best-Practice Recommendations for a Secure Zimbra Configuration

The following recommendations are provided to ensure a best-practice security configuration. This includes the following:

  • Require encrypted logins
  • Requiring secure interprocess communications

SSL Certificates

1. Be sure to have properly configure SSL Certificates

References: see these pages:

2. If possible, use only Commercial CA-Signed Certs


Most secure is to only allow secure methods of accessing the system; however, be careful in making these changes, as all processes need to be configured to connect only to upstream encrypted listeners.

1. Configure the proxy to offer only encrypted HTTPS protocols (run this on every proxy):

zmprov gs `zmhostname` zimbraReverseProxyMailMode
zmprov ms `zmhostname` zimbraReverseProxyMailMode https

2. Configure the mailstore to offer only encrypted HTTPS procotol:

zmprov gs `zmhostname` zimbraMailMode
zmprov ms `zmhostname` zimbraMailMode https

3. Require Proxy to connect to upstream via SSL

zmprov gs `zmhostname` zimbraReverseProxySSLToUpstreamEnabled
zmprov ms `zmhostname` zimbraReverseProxySSLToUpstreamEnabled TRUE

Encrypted Logins


zmprov gs `zmhostname` zimbraMailClearTextPasswordEnabled
zmprov ms `zmhostname` zimbraMailClearTextPasswordEnabled FALSE


zmprov gs `zmhostname` zimbraImapCleartextLoginEnabled
zmprov ms `zmhostname` zimbraImapCleartextLoginEnabled FALSE
zmprov gs `zmhostname` zimbraReverseProxyImapStartTlsMode
zimbraReverseProxyImapStartTlsMode: only


zmprov gs `zmhostname` zimbraPop3CleartextLoginEnabled
zmprov ms `zmhostname` zimbraPop3CleartextLoginEnabled FALSE

zmprov gs `zmhostname` zimbraReverseProxyPop3StartTlsMode
zimbraReverseProxyPop3StartTlsMode: only

Secure Interprocess Communication

1. Make sure LDAP is supporting STARTTLS - should be set to "1":

zmlocalconfig ldap_starttls_supported
zmlocalconfig -e ldap_starttls_supported=1

2. Require interprocess security - should be set to 1:

zmlocalconfig zimbra_require_interprocess_security
zmlocalconfig -e zimbra_require_interprocess_security=1

3. Require secure LDAP from mailboxd - should be set to "true":

zmlocalconfig ldap_starttls_required
zmlocalconfig -e ldap_starttls_required=true

References: see also TLS/STARTTLS_Localconfig_Values

== End-to-End Encryption

1. Use S/MIME

Reference: see SMIME_Certificates


1. Configure your firewall to allow *only* required ports:

Reference: see Ports

2. Restrict external ssh to use two-factor authentication.

The Google Authenticator is one option for this:

Verified Against: ZCS 8.0 Date Created: 06/28/2014
Article ID: Date Modified: 2014-06-28

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