Difference between revisions of "SecureConfiguration"

m
(reorder items a little and reorganize a bit along with some wording changes)
Line 12: Line 12:
 
* Requiring secure interprocess communications
 
* Requiring secure interprocess communications
 
* Use end-to-end encryption with S/MIME
 
* Use end-to-end encryption with S/MIME
 +
 +
== Firewall ==
 +
 +
* Configure your firewall to allow '''only''' required [[Ports]].
 +
* Restrict SSH and admin access via a VPN or known IP addresses only.
 +
* Configure SSH to use [https://en.wikipedia.org/wiki/Two-factor_authentication two factor authentication].  References:
 +
** https://www.digitalocean.com/community/tutorials/how-to-protect-ssh-with-two-factor-authentication
 +
** https://sysconfig.org.uk/two-factor-authentication-with-ssh.html
  
 
== SSL Certificates ==
 
== SSL Certificates ==
  
1. Be sure to have properly configure SSL Certificates
+
1. Be sure to have properly configure SSL Certificates. Follow these references:
 
 
References: see these pages:
 
 
* [[Administration_Console_and_CLI_Certificate_Tools]]
 
* [[Administration_Console_and_CLI_Certificate_Tools]]
 
* [[SSL_certificates_per_domain]]
 
* [[SSL_certificates_per_domain]]
  
 
2. If possible, use only Commercial CA-Signed Certs  
 
2. If possible, use only Commercial CA-Signed Certs  
 +
 +
== 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: [[TLS/STARTTLS_Localconfig_Values]]
  
 
== Services ==
 
== Services ==
Line 44: Line 69:
 
  zmprov ms `zmhostname` zimbraReverseProxySSLToUpstreamEnabled TRUE
 
  zmprov ms `zmhostname` zimbraReverseProxySSLToUpstreamEnabled TRUE
  
== Encrypted Logins ==
+
== Encrypted Authentication ==
 +
 
 +
All authentication must be done over TLS/SSL.  Restart services after making these changes.
  
1. HTTPS
+
=== HTTP ===
  
 
  zmprov gs `zmhostname` zimbraMailClearTextPasswordEnabled
 
  zmprov gs `zmhostname` zimbraMailClearTextPasswordEnabled
  zmprov ms `zmhostname` zimbraMailClearTextPasswordEnabled FALSE
+
  zmprov ms `zmhostname` zimbraMailClearTextPasswordEnabled FALSE # if not already
  
2. IMAP4-SSL
+
=== IMAP4 ===
  
 
  zmprov gs `zmhostname` zimbraImapCleartextLoginEnabled
 
  zmprov gs `zmhostname` zimbraImapCleartextLoginEnabled
  zmprov ms `zmhostname` zimbraImapCleartextLoginEnabled FALSE
+
  zmprov ms `zmhostname` zimbraImapCleartextLoginEnabled FALSE # if not already
  
 
  zmprov gs `zmhostname` zimbraReverseProxyImapStartTlsMode
 
  zmprov gs `zmhostname` zimbraReverseProxyImapStartTlsMode
 
  zimbraReverseProxyImapStartTlsMode: only
 
  zimbraReverseProxyImapStartTlsMode: only
  
3. POP3-SSL
+
=== POP3 ===
  
 
  zmprov gs `zmhostname` zimbraPop3CleartextLoginEnabled
 
  zmprov gs `zmhostname` zimbraPop3CleartextLoginEnabled
  zmprov ms `zmhostname` zimbraPop3CleartextLoginEnabled FALSE
+
  zmprov ms `zmhostname` zimbraPop3CleartextLoginEnabled FALSE # if not already
  
 
  zmprov gs `zmhostname` zimbraReverseProxyPop3StartTlsMode
 
  zmprov gs `zmhostname` zimbraReverseProxyPop3StartTlsMode
 
  zimbraReverseProxyPop3StartTlsMode: only
 
  zimbraReverseProxyPop3StartTlsMode: only
  
== Secure Interprocess Communication ==
+
=== SMTP ===
 
 
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
 
  
 
  zmprov gs `zmhostname` zimbraMtaTlsAuthOnly
 
  zmprov gs `zmhostname` zimbraMtaTlsAuthOnly
 +
zmprov ms `zmhostname` zimbraMtaTlsAuthOnly TRUE # if not already
  
If not already, set to "TRUE":
+
Use opportunistic outbound STARTTLS.  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:
 
 
zmprov ms `zmhostname` zimbraMtaTlsAuthOnly TRUE
 
 
 
2. Use opportunistic outbound STARTLS
 
  
 
  zmlocalconfig postfix_smtp_tls_security_level
 
  zmlocalconfig postfix_smtp_tls_security_level
 +
zmlocalconfig -e postfix_smtp_tls_security_level=may # if not already
  
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:
+
Use opportunistic inbound STARTTLS.  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
 
  zmprov gs `zmhostname` zimbraMtaTlsSecurityLevel
 
+
zmprov ms `zmhostname` zimbraMtaTlsSecurityLevel may
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:
 
 
 
  zmprov ms `zmhostname` zimbraMtaTlsSecurityLevel may
 
 
 
4. Restart the postfix MTA
 
 
 
  zmmtactl restart
 
  
 
== End-to-End Encryption ==
 
== End-to-End Encryption ==
Line 125: Line 118:
  
 
[https://www.zimbra.org/extend/items/view/zimbra-openpgp-zimlet Zimbra OpenPGP Zimlet]
 
[https://www.zimbra.org/extend/items/view/zimbra-openpgp-zimlet Zimbra OpenPGP Zimlet]
 
== 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/
 
  
 
----------------------------------------------------------------------------------------------------------------------------
 
----------------------------------------------------------------------------------------------------------------------------

Revision as of 18:49, 5 February 2016

Best-Practice Recommendations for a Secure Zimbra Configuration

   KB 21032        Last updated on 2016-02-5  




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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

Firewall

SSL Certificates

1. Be sure to have properly configure SSL Certificates. Follow these references:

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

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: TLS/STARTTLS_Localconfig_Values

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

Note: it is possible to use "redirect" here, which will redirect HTTP requests to HTTPS using a "302 Redirect" response code. Please note, however, that some clients (such as ActiveSync devices) will not honor a 302 Redirect, and may try to pass unencrypted login information. It is recommended to use only https here for highest security.

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 Authentication

All authentication must be done over TLS/SSL. Restart services after making these changes.

HTTP

zmprov gs `zmhostname` zimbraMailClearTextPasswordEnabled
zmprov ms `zmhostname` zimbraMailClearTextPasswordEnabled FALSE # if not already

IMAP4

zmprov gs `zmhostname` zimbraImapCleartextLoginEnabled
zmprov ms `zmhostname` zimbraImapCleartextLoginEnabled FALSE # if not already
zmprov gs `zmhostname` zimbraReverseProxyImapStartTlsMode
zimbraReverseProxyImapStartTlsMode: only

POP3

zmprov gs `zmhostname` zimbraPop3CleartextLoginEnabled
zmprov ms `zmhostname` zimbraPop3CleartextLoginEnabled FALSE # if not already
zmprov gs `zmhostname` zimbraReverseProxyPop3StartTlsMode
zimbraReverseProxyPop3StartTlsMode: only

SMTP

zmprov gs `zmhostname` zimbraMtaTlsAuthOnly
zmprov ms `zmhostname` zimbraMtaTlsAuthOnly TRUE # if not already

Use opportunistic outbound STARTTLS. 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 postfix_smtp_tls_security_level
zmlocalconfig -e postfix_smtp_tls_security_level=may # if not already

Use opportunistic inbound STARTTLS. 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:

zmprov gs `zmhostname` zimbraMtaTlsSecurityLevel
zmprov ms `zmhostname` zimbraMtaTlsSecurityLevel may

End-to-End Encryption

1. Use S/MIME

Reference: see SMIME_Certificates

2. As an Open Source alternative, you can use as well the OpenPGP Zimlet, by Barry de Graaff

Zimbra OpenPGP Zimlet


Verified Against: ZCS 8.0 Date Created: 06/28/2014
Article ID: https://wiki.zimbra.com/index.php?title=SecureConfiguration Date Modified: 2016-02-05



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