I propose that the default 600s/10minute find time is a better test duration for this ban. The altered 120s findtime sounds reasonable until you consider that attackers can simply throttle to 3 attempts per minute and never be banned.
The remaining non default jail settings of maxretry = 7 and bantime = 3600 I believe are good.
Nginx should be connecting over the local interface, not to the IP the resolver gives it. Elsewhere in this file proxy_pass uses 127.0.0.1 as it should.
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.
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.
* Set ssl_stapling_verify to off per https://sslmate.com/blog/post/ocsp_stapling_in_apache_and_nginx ('on' has no security benefits).
* Set resolver to 127.0.0.1, instead of Google Public DNS, because we might as well use our local nameserver anyway.
* Remove the commented line which per the link above would never be necessary anyway.
OCSP seems to work just fine after these changes.
* Split the nginx templates again so we have just the part needed to make a domain do a redirect separate from the rest.
* Add server blocks to the nginx config for these domains.
* List these domains in the SSL certificate install admin panel.
* Generate default 'www' records just for domains we provide default redirects for.
Fixes#321.
* install the munin-node package
* don't install munin-plugins-extra (if the user wants it they can add it)
* expose the munin www directory via the management daemon so that it can handle authorization, rather than manintaining a separate password file
Redirect using the 'return' directive and the built-in
variable '$request_uri' to avoid any capturing, matching
or evaluation of regular expressions.
It's best practice. See: http://wiki.nginx.org/Pitfalls#Taxing_Rewrites
nginx/postfix use a new pre-generated dh2048.pem file. dovecot generates the bits on its own.
ssllabs.com reports that TLS_DHE ciphers went from 1024 to 2048 bits as expected. The ECDHE ciphers remain at 256 bits --- no idea what that really means. (This tests nginx only. I haven't tested postfix/dovecot.)
see https://discourse.mailinabox.email/t/fips-ready-for-ssl-dhec-key-exchange/76/3
This lets roundcube's manageseive plugin do cool things like vacation responses.
Also:
* Run the spam filtering sieve script out of a global sieve file that we'll place in /etc/dovecot. It is no longer necessary to create per-user sieve files for this. Remove them with a new migration. Remove the code that created them.
* Corrects the spam script. Backslashes were double-escaped probably because this script started embedded within the bash script. Not sure how this was working until now.
this adapts work by @h8h in #103
This re-implements part of PR #69 by @mkropat, who wrote:
By default, Postfix adds a Received header — on all mail that you send —
that lists the IP of the device you sent the mail from. This feature is
great if you're a mail provider and you need to debug why one user is
having sending issues. This feature is not so great if you run your own
mail server and you don't want every recipient of every email you send
to know the device and IP you sent the email from.
To limit this filtering to outgoing mail only, we apply the filters just
to the submission port. See these guides [1] [2] for more context.
[1] http://askubuntu.com/a/78168/11259
[2] http://www.void.gr/kargig/blog/2013/11/24/anonymize-headers-in-postfix/
Joshua Tauberer
anoma
Stefan Dimitrov
PortableTech
kri3v
Marc Schiller
bizonix
H8H
BiZoNiX
ikarus
Norman
David Piggott
jkaberg