This is the third part of a five part tutorial that will show you how to install a full featured email server on your Raspberry Pi. This tutorial covers how to set up Webmail with Squirrelmail.

The parts are:
The Introduction & Contents Page (read first)
Raspberry Pi Email Server Part 1: Postfix
Raspberry Pi Email Server Part 2: Dovecot
Raspberry Pi Email Server Part 3: Squirrelmail
Raspberry Pi Email Server Part 4: Spam Detection with Spamassassin
Raspberry Pi Email Server Part 5: Spam Sorting with LMTP & Sieve

Installing Apache

If you don't already have apache installed (you might if you've followed my wordpress tutorial), then install it now.

sudo apt-get update
sudo apt-get install apache2

Enable the SSL apache module so that you can use HTTPS:

sudo a2enmod ssl

There are some "pre-made" virtualhost configurations that come with apache. This command will enable the "default-ssl" virtualhost, by creating a symbolic link from /etc/apache2/sites-available/default-ssl to /etc/apache2/sites-enabled/default-ssl:

sudo a2ensite default-ssl

Now reload apache to make the changes take effect:

sudo service apache2 reload

If you type the IP address or hostname of the pi into a web browser now, you should see the default Apache test page:

If you try the https version, you'll get a certificate error because you are using a self-signed SSL certificate. If you like, you can follow my CAcert tutorial to get a free SSL certificate for your domain, or you can just store an exception for the certificate and generate a proper one later.

That's it for Apache. If you want to know more about setting up Apache for multiple websites, subdomains, and SSL configurations, I suggest you read my tutorial explaining Apache's VirtualHost files.

Installing Squirrelmail

Now we need to install squirrelmail:

sudo apt-get update
sudo apt-get install squirrelmail

The basic configuration for squirrelmail is really easy, and can be done with the setup script. To run the script, use this command:

sudo squirrelmail-configure

Choose “D” for pre-defined settings

Now type “dovecot” and hit enter

Press enter to continue, then save and quit (press Q and save when prompted, or press S then Q).

The configuration script creates a configuration file for apache in /etc/squirrelmail/apache.conf. You need to create a symbolic link so that Apache2 will load your Squirrelmail apache configuration file when it starts up.

On Raspbian Wheezy, the command is:

sudo ln -s /etc/squirrelmail/apache.conf /etc/apache2/conf.d/squirrelmail.conf

On Raspbian Jessie, the apache configuration directory structure is more like ubuntu, with separate folders for configuration files that are available and files that are enabled. This command will create a symlink from the directory where enabled configuration is stored, to squirrelmail's apache configuration file:

sudo ln -s /etc/squirrelmail/apache.conf /etc/apache2/conf-enabled/squirrelmail.conf

On a related note, there's a convenience command a2enconf that works similarly to a2ensite: it creates a symlink from the conf-available directory to the conf-enabled directory. You should use this in situations where config already exists in conf-available, e.g. sudo a2enconf squirrelmail would create a symlink for a file called squirrelmail.conf.

Now reload Apache one more time so that it reads the config file we just symlinked:

sudo service apache2 reload

Now visit the IP address or hostname of your Pi again, but add /squirrelmail to the path, e.g. 192.168.1.174/squirrelmail, you should see the login page:

The squirrelmail configuration file just adds an alias that should affect every virtualhost, so if you install a wordpress site or something like that on your pi, you will be able to get to the squirrelmail login page by visiting yourdomain.com/squirrelmail.

Redirect http to https for secure login

Since you don't want to send your login details and confidential information over the internet without SSL, it's best to redirect all http URLs to https.

The default squirrelmail apache configuration file at /etc/squirrelmail/apache.conf contains some rewrite rules we can use, we just need to uncomment them. Open the file and uncomment the lines by removing the # at the start of each so that it looks like this:

<IfModule mod_rewrite.c>
  <IfModule mod_ssl.c>
    <Location /squirrelmail>
      RewriteEngine on
      RewriteCond %{HTTPS} !^on$ [NC]
      RewriteRule . https://%{HTTP_HOST}%{REQUEST_URI}  [L]
    </Location>
  </IfModule>
</IfModule>

This configuration makes sure that the rewrite and ssl modules are enabled, and does nothing if they aren't. We already enabled the ssl module earlier, so all we need to do now is enable the rewrite module:

sudo a2enmod rewrite

And reload Apache:

sudo service apache2 reload

Now if you visit the HTTP page, you should be redirected to HTTPS.

Optional: Configuring Apache to serve Squirrelmail on a subdomain

If you would like to move the login page to the root of your domain (i.e. so that yourdomain.com would serve the login page for squirrelmail), or if you would like to serve it on a subdomain like mail.yourdomain.com, you can edit the configuration file. If not, you can skip this section.

By default, this line in /etc/squirrelmail/apache.conf means that http://www.yourdomain.com/squirrelmail will load squirrelmail:

Alias /squirrelmail /usr/share/squirrelmail

If you would rather have webmail on a subdomain like mail.yourdomain.com then you could edit the /etc/squirrelmail/apache.conf file to look like this (comment out the rest):

<VirtualHost *:80>
  DocumentRoot /usr/share/squirrelmail
  ServerName mail.yourdomain.com


<Directory /usr/share/squirrelmail>
  Options FollowSymLinks
  <IfModule mod_php5.c>
    php_flag register_globals off
  </IfModule>
  <IfModule mod_dir.c>
    DirectoryIndex index.php
  </IfModule>

  # access to configtest is limited by default to prevent information leak
  <Files configtest.php>
    order deny,allow
    deny from all
    allow from 127.0.0.1
  </Files>
</Directory>
</VirtualHost>

Note that if you want to serve mail on a subdomain, then that subdomain needs a DNS record, so edit your records with your DNS provider accordingly.

However, the virtualhost code above only does HTTP. You also want an HTTPS virtualhost for the subdomain on port 443:

<IfModule mod_ssl.c>
<VirtualHost *:443>
  DocumentRoot /usr/share/squirrelmail
  ServerName mail.yourdomain.com

<Directory /usr/share/squirrelmail>
  Options FollowSymLinks
  <IfModule mod_php5.c>
    php_flag register_globals off
  </IfModule>
  <IfModule mod_dir.c>
    DirectoryIndex index.php
  </IfModule>

  # access to configtest is limited by default to prevent information leak
  <Files configtest.php>
    order deny,allow
    deny from all
    allow from 127.0.0.1
  </Files>
</Directory>

ErrorLog ${APACHE_LOG_DIR}/error.log
LogLevel warn
CustomLog ${APACHE_LOG_DIR}/ssl_access.log combined

SSLEngine on
SSLCertificateFile    /etc/ssl/certs/your-ssl-certificate.crt
SSLCertificateKeyFile /etc/ssl/private/your-ssl-certificate-keyfile.key


</VirtualHost>
</IfModule>

If you use this configuration, the rewrite rules from the "rewrite to HTTPS" section (the ones from the default config file) won't work. If you want an HTTPS-only solution, you can replace the virtualhost for port 80 with this:

<VirtualHost *:80>
ServerName mail.yourdomain.com
<IfModule mod_rewrite.c>
  <IfModule mod_ssl.c>
    <Location />
      RewriteEngine on
      RewriteCond %{HTTPS} !^on$ [NC]
      RewriteRule . https://%{HTTP_HOST}%{REQUEST_URI}  [L]
    </Location>
  </IfModule>
</IfModule>
</VirtualHost>

As before, make sure you have the rewrite module enabled:

sudo a2enmod rewrite

Now reload apache:

sudo service apache2 restart

If you get an error like this:

[....] Restarting web server: apache2[Fri Dec 06 15:54:04 2013] [warn] _default_ VirtualHost overlap on port 443, the first has precedence

Then add NameVirtualHost *:443 to the start of the SSL VirtualHost block, i.e.:

NameVirtualHost *:443
<IfModule mod_ssl.c>
<VirtualHost *:443>
  DocumentRoot /usr/share/squirrelmail
  ServerName mail.yourdomain.com
...

For more info on HTTP and HTTPS VirtualHost configuration on Apache2, see this tutorial of mine.

If all went to plan then you can navigate to mail.yourdomain.com and you should see the squirrelmail login page (you might need to forward some ports on your router if you haven't already - see the next section):

Port Forwarding

Squirrelmail will log in to your IMAP server on port 143 to display your emails. It doesn’t need to authenticate because it’s in your network (remember the permit_mynetworks parameter from the previous tutorials?). You don’t need to worry about it being an unencrypted connection, because the data isn't actually travelling over any insecure networks (the connection is internal). Similarly, you don’t need to open port 143 (“plain” imap without SSL/TLS) on your router because the connection happens within the Pi, and the content is actually served to you, the user, on port 443 (https).

So you do need to open ports 80 and 443 for http and https like below:

Testing

Before you start testing your webmail, make sure that the permit_mynetworks parameters are uncommented in your postfix confuguration file /etc/postfix/main.cf (in both your smtpd_recipient_restrictions and smtpd_helo_restrictions).

Now reload your postfix configuration:

sudo service postfix reload

Try sending and receiving emails from within Squirrelmail. You should have no problems, but if you do please post a comment and I’ll try to help you out.

Customising the Squirrelmail Login

To customise the login page, run the configuration wizard:

sudo squirrelmail-configure

1. Select “1″ (organisation preferences)
2. Select “7″ and change to your domain (e.g. http://www.samhobbs.co.uk)
3. Select “8″ and change to you/your organisation’s name

Squirrelmail Plugins

There are loads of plugins available for Squirrelmail, for all kinds of things. On most systems, these plugins are installed by downloading a .zip file to your server, unzipping the plugin to the right location and then tinkering with the settings manually.

Thankfully, some of the most commonly used plugins are available from the Raspbian repositories, so installation is much simpler. Here is a list of the plugins in the repo:

1. squirrelmail-compatibility
2. squirrelmail-decode
3. squirrelmail-locales
4. squirrelmail-lockout
5. squirrelmail-logger
6. squirrelmail-quicksave
7. squirrelmail-secure-login
8. squirrelmail-sent-confirmation
9. squirrelmail-spam-buttons
10. squirrelmail-viewashtml

The one I think is most useful and the one I’m going to use as an example is lockout.

To use the lockout package, we need to install the compatibility package, which basically makes sure that plugins built for different versions of squirrelmail can still work with the version you are running.

sudo apt-get update
sudo apt-get install squirrelmail-compatibility

Now we need to enable the plugin:

sudo squirrelmail-configure

1. select “8″
2. select “compatibility”
3. select “S” (to save)
4. select “Q” (to quit)

That’s all you need to do for the compatibility plugin. Now we can install the lockout plugin:

sudo apt-get install squirrelmail-lockout

Now for the configuration:

sudo squirrelmail-configure

Make sure that lockout is enabled

Now we can manually edit some settings. Before starting, I like to back up the default config files for reference:

cd /etc/squirrelmail
sudo cp lockout-table.php lockout-table.php.BAK
sudo cp lockout-config.php lockout-config.php.BAK

Now edit the lockout-table.php file. Read the comments in the file for an explanation of how the table works. I wanted to disable logins for the user “admin”, so I commented out the examples at the end of the file and replaced them with this:

user:		admin		locked_out.php

Now edit lockout-config.php and set $use_lockout_rules = 1; to turn on lockouts.

Now try and log in as the user you locked out, and you should get this message: “Access Denied / Please contact your system administrator”.

We can also lock out IP addresses of users who enter incorrect username/password combinations repeatedly. To do this, open lockout-config.php and set $max_login_attempts_per_IP = '3:5:0'.

The first number in this parameter is the number of incorrect attempts that are allowed before a ban. The second number is the time frame for these incorrect attempts, and the last number is the amount of time the ban lasts for when activated (0 is forever).

So, the setting I gave you above means that anyone who makes 3 incorrect attempts to authenticate in 5 minutes is permanently banned.

When a successful login is made, the count is reset to 0.

Data on current bad login attempts and bans is stored here: /var/lib/squirrelmail/data/lockout_plugin_login_failure_information

The plugin will add entries like this to keep track of bad logins:

999.999.99.99_login_failure_times=1386774015:1386774034:1386774053
999.999.99.99_TOO_MANY_FAILED_LOGIN_ATTEMPTS=PERMANENT

…where 999.999.99.99 is the offending IP address

If you accidentally ban yourself, you’ll have to log in via SSH and edit this file to remove those lines.

That’s it, you’re done! Have fun exploring the other plugins!

The next two tutorials, Part 4 and Part 5 deal with spam detection and filtering.