I wrote this little Python program a while ago and now people are starting to email me about it, asking for it to be part of the DenyHosts Debian packages so I figured I’d write a quick article on it.

If you’re like my developers, you’ll find yourself getting banned from servers all the time and have to come speak to someone like me (your sys engineer/admin), or maybe you are an admin and are sick of people banning themselves and want and easy way to unban them.

So give this a try:

https://github.com/kura/denyhosts-unban

From the GitHub page you can download either the tarballs, zipballs or a Debian .deb package. Install it using the instructions in the README and you’re good to go.

sudo denyhosts-unban 10.0.0.1 …

If like me you run in to issue when using OpenJDK, my issues come from it’s memory problems when you’re allocating and using large amounts of memory - mostly for Solr where we’re concerned but obviously I’d switch for other high memory usage instances too.

So without further ado, lets get the installation going.

You’ll need Debian’s “add-apt-repository”, on servers this doesn’t usually come by default so we’ll need to install it.

sudo apt-get install python-software-properties

Next we need to add Java’s PPA.

sudo add-apt-repository ppa:sun-java-community-team/sun-java6

Once this is done we’ll need to update our apt caches and install Java 6.

sudo apt-get install sun-java6-jdk

Now that this is installed we should get the Java version, remember it for future.

java -version

You’ll get something like this

java version "1.6.0_20" OpenJDK Runtime Environment (IcedTea6 1.9 …

You’ll need mkpasswd, on Debian 6 and Ubuntu 12.04 you can install this using:

sudo apt-get install whois

It is pretty weird that it comes with the whois package though…

And then run

mkpasswd -m sha-512

I have built and released an open-source email server in the past for testing send rates and speeds, this project was called SimpleMTA and is available here.

Recently I have rebuilt this project for an internal project at work using the Tornado framework. Sadly this project as a whole cannot be released but a version of this code will be released in the near future.

Until that is released I have launched a new service called blackhole.io

I’ve recently been toying with my Raspberry Pi mirror including moving it out on to Amazon’s S3. I’ve written an article on how to back up to S3, but that isn’t enough when it comes to serving data from S3.

I needed the ability to RSYNC data from the official Raspberry Pi servers on to mine and then in to S3 and for that I used s3fs and FUSE.

sudo apt-get install fuse-utils

24 hours of SSH attacks against a single server, visualised on a world map using Python.

When a country stays lit up for more than 1 tick of the clock in the left hand corner it means that multiple attacks are happening from different IP addresses. An attacker is banned after;

• 1 failed root login,
• 3 failed user logins (including invalid users) and
• 3 failed system logins.

I have several servers powering syslog including it’s Raspberry Pi mirror, load balancer and email servers. All of my servers are hosted using Linode in their London data centre and have Linode’s back-up system doing both daily and weekly snapshots.

For the app and database servers I do server-side backups storing each website and it’s database in it’s own folder within /backup in case I require a quick back-up to fix something, rather than the server has died.

This is all well and good but I like having an off-site backup too and for that I use S3…

The unattended-upgrades package used on Debian is based on the one from Ubuntu. It is generally pretty safe in my opinion but I only ever enable it for security upgrades.

apt-get install unattended-upgrades apticron

APT::Periodic::Enable "1";
APT::Periodic::Update-Package-Lists "1";
APT::Periodic::AutocleanInterval "7";
APT::Periodic::Unattended-Upgrade "1";
Unattended-Upgrade::Mail "**YOUR_EMAIL_HERE**";

// Automatically upgrade packages from these (origin, archive) pairs
Unattended-Upgrade::Allowed-Origins {
    "${distro_id} stable";
    "${distro_id} ${distro_codename}-security";
};

// Automatically reboot *WITHOUT CONFIRMATION* if a
 // the file /var/run/reboot-required is found after the upgrade
 Unattended-Upgrade::Automatic-Reboot "false";