SecureConfiguration

Revision as of 21:46, 28 June 2014 by Thom (talk | contribs)
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Article Information

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:

  • Run services only on secure channels
  • Require encrypted logins
  • Requiring secure interprocess communications
  • Use end-to-end encryption with S/MIME

SSL Certificates

1. Be sure to have properly configure SSL Certificates

References: see these pages:

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

Services

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

1. HTTPS

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

2. IMAP4-SSL

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

3. POP3-SSL

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

SMTP

1. Disallow plaintext SMTP AUTH logins

zmlocalconfig -e postfix_smtpd_tls_auth_only=yes
postconf -e smtpd_tls_auth_only=yes

2. Use opportunistic outbound STARTLS

zmlocalconfig postfix_smtp_tls_security_level

If not already, set to use "may". Note that it is not usually possible to use "encrypt" here, as you cannot require remote MTAs to use encryption:

 zmlocalconfig -e postfix_smtp_tls_security_level=may

3. Use opportunistic inbound STARTTLS

zmprov gs `zmhostname` zimbraMtaTlsSecurityLevel

If not already, set to use "may". Note that it is not usually possible to use "encrypt" here, as you cannot require remote MTAs to use encryption:

 mprov ms `zmhostname` zimbraMtaTlsSecurityLevel may

4. Restart postfix

 zmmtactl restart

== End-to-End Encryption

1. Use S/MIME

Reference: see SMIME_Certificates

Firewall

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: http://www.howtogeek.com/121650/how-to-secure-ssh-with-google-authenticators-two-factor-authentication/



Verified Against: ZCS 8.0 Date Created: 06/28/2014
Article ID: https://wiki.zimbra.com/index.php?title=SecureConfiguration Date Modified: 2014-06-28



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