Group-Office on separate mail- and webserver howto

I'm going to show an ideal setup of a separate mailserver and Group-Office server.

On both servers we'll install a minimal Debian 6.

Secure access

First we'll secure the remote access on both servers:

Install fail2ban. This is a program that will monitor various log files and blocks users who make more then 3 failed login attempts.

apt-get install fail2ban

Install sudo to allow normal users to execute root commands:

apt-get install sudo

Then add a personal user:

adduser <username>
adduser <username> sudo

Generate an ssh keypair for your username on your own machine. We don't cover this here.

Add the public key to:

/home/<username>/.ssh/authorized_keys

Set the right permissions:

chmod 700 /home/<username>/.ssh/
chmod 600 /home/<username>/.ssh/authorized_keys

Now test the SSH login with your keypair and make sure it works because we're going to disable any other login method. Make sure this user can use sudo too.

When this works disable root login through SSH and disable login with normal passwords:

Change /etc/ssh/sshd_config:

PermitRootLogin no
PasswordAuthentication no
ChallengeResponseAuthentication no

Enabling SSL

This is for a self-signed certificate. You probably want to purchase a real one.

mkdir /etc/apache2/ssl && /usr/sbin/make-ssl-cert /usr/share/ssl-cert/ssleay.cnf /etc/apache2/ssl/apache.pem

Edit /etc/apache2/sites-enabled/000-default:

SSLEngine On
SSLCertificateFile /etc/apache2/ssl/apache.pem

Change the VirtualHost port from *:80 to *:443.