While not widely supported, there are some browser addons that can
validate DNSSEC and TLSA for additional out-of-band verification of
certificates when browsing the web. Costs nothing to implement and
might improve security in some situations.
Recidive can be thought of as FAIL2BAN checking itself. This setup will monitor the FAIL2BAN log and if 10 bans are seen within one day activate a week long ban and email the mail in a box admin that it has been applied . These bans survive FAIL2BAN service restarts so are much stronger which obviously means we need to be careful with them.
Our current settings are relatively safe and definitely not easy to trigger by mistake e.g to activate a recidive IP jail by failed SSH logins a user would have to fail logging into SSH 6 times in 10 minutes, get banned, wait for the ban to expire and then repeat this process 9 further times within a 24 hour period.
The default maxretry of 5 is much saner but that can be applied once users are happy with this jail. I have been running a stronger version of this for months and it does a very good job of ejecting persistent abusers.
Explicitly set the timings and counts for the dovecot jail rather than change the global [DEFAULT] and inherit it for this one jail. These settings are far too safe so a future PR should increase security here.
Reverts the remaining FAIL2BAN settings to default: findtime 600 and maxretry 3. As jail settings override default settings this was hardly being used anyway so it is better to explicitly set it per jail as and when required.
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This is a minor update to v0.11, which was a major update. Please read v0.11's advisories.
* The administrator@ alias was incorrectly created starting with v0.11. If your first install was v0.11, check that the administrator@ alias forwards mail to you.
* Intrusion detection rules (fail2ban) are relaxed (i.e. less is blocked).
* SSL certificates could not be installed for the new automatic 'www.' redirect domains.
* PHP's default character encoding is changed from no default to UTF8. The effect of this change is unclear but should prevent possible future text conversion issues.
* User-installed SSL private keys in the BEGIN PRIVATE KEY format were not accepted.
* SSL certificates with SAN domains with IDNA encoding were broken in v0.11.
* Some IDNA functionality was using IDNA 2003 rather than IDNA 2008.
Modify outgoing_mail_header_filters and mail-postfix.sh
files to result in the primary hostname, and the public
ip of the server showing in the first mail header route
instead of unknown and 127.0.0.1. This could help lower
the spam score of mail sent from your server to some
public mail services.
Ban time was too low for preventing ssh brute force attacks, this change also allows to keep the auth.log more clean and avoid wasting cpu and i/o on this.
Bots eventually will flag your IP as secure and move along.
No legitimate admin will require 20 login attempts. The default 6 is a sane middle ground especially since in 10 minutes they can try again or immediately from another IP anyway.
A 60 second/1 minute ban time is not long enough to counter brute force attacks which is the main purpose of fail2ban for mail in a box. The default bantime of 10 minutes is still sane and I think we have proven fail2ban is reliable enough not to cause problems in general. It is not worth sacrificing security for the rare case where an admin locks themselves out for 10 minutes.
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Advisories:
* Users can no longer spoof arbitrary email addresses in outbound mail. When sending mail, the email address configured in your mail client must match the SMTP login username being used, or the email address must be an alias with the SMTP login username listed as one of the alias's targets.
* This update replaces your DKIM signing key with a stronger key. Because of DNS caching/propagation, mail sent within a few hours after this update could be marked as spam by recipients. If you use External DNS, you will need to update your DNS records.
* The box will now install software from a new Mail-in-a-Box PPA on Launchpad.net, where we are distributing two of our own packages: a patched postgrey and dovecot-lucene.
Mail:
* Greylisting will now let some reputable senders pass through immediately.
* Searching mail (via IMAP) will now be much faster using the dovecot lucene full text search plugin.
* Users can no longer spoof arbitrary email addresses in outbound mail (see above).
* Fix for deleting admin@ and postmaster@ addresses.
* Roundcube is updated to version 1.1.2, plugins updated.
* Exchange/ActiveSync autoconfiguration was not working on all devices (e.g. iPhone) because of a case-sensitive URL.
* The DKIM signing key has been increased to 2048 bits, from 1024, replacing the existing key.
Web:
* 'www' subdomains now automatically redirect to their parent domain (but you'll need to install an SSL certificate).
* OCSP no longer uses Google Public DNS.
* The installed PHP version is no longer exposed through HTTP response headers, for better security.
DNS:
* Default IPv6 AAAA records were missing since version 0.09.
Control panel:
* Resetting a user's password now forces them to log in again everywhere.
* Status checks were not working if an ssh server was not installed.
* SSL certificate validation now uses the Python cryptography module in some places where openssl was used.
* There is a new tab to show the installed version of Mail-in-a-Box and to fetch the latest released version.
System:
* The munin system monitoring tool is now installed and accessible at /admin/munin.
* ownCloud updated to version 8.0.4. The ownCloud installation step now is reslient to download problems. The ownCloud configuration file is now stored in STORAGE_ROOT to fix loss of data when moving STORAGE_ROOT to a new machine.
* The setup scripts now run `apt-get update` prior to installing anything to ensure the apt database is in sync with the packages actually available.
* Add a migration to delete any existing DKIM key so that existing machines get a fresh 2048-bit key. (Sadly we don't support key rotation so the change is immediate.)
* Because the DNS record for a 2048-bit key is so much longer, the way we read OpenDKIM's DNS record text file had to be modified to combine an arbitrary number of TXT record quoted ("...") strings.
* When writing out the TXT record value, the string must be split into quoted ("...") strings with a maximum length of 255 bytes each, per the DNS spec.
* Added a changelog entry.
Currently MiaB creates 1024 bit keys which is seen as a minimum standard
by several providers such as Google who already uses a 2048 bit key.
Increasing the keysize beyond 2048 is an issue as it often goes beyond
supported DNS record sizes.
