Last night I had some free time to play with my network, and I ran  tcpdump out of curiosity. For a while, I’ve been interested to analyze what traffic is going through my home network, and the result of my test pushed me to get to work. I have a bunch of Raspberry Pi devices in my drawers, so, the simplest thing that I can do is get one and install Elastic SIEM on it. For those of you, who don’t know what SIEM is, it stands for Security Information and Event Management. My hope was that with it, I will be able to get a better understanding of the traffic on my home network.

Installing Elastic SIEM on Raspberry Pi

The first thing I had to do is to install the ELK stack on a Raspberry Pi. There are not too many good articles that explain how to set up Elastic SIEM on your Pi. According to Elastic, Elastic SIEM is generally available in Elastic Stack 7.6. So, installing the Elastic Stack should do the work.

A couple of notes before that:

  1. The first thing to keep in mind is that 8GB is the minimum requirement for the ELK stack. You can get around with 2GB Pi, but if you want to run the whole stack (Elasticsearch, Logstash, and Kibana) on a single device, make sure that you order Raspberry Pi 4 Model B Quad Core 64 Bit with 4GB[ad]. Even this one is a stretch if you collect a lot of information. A good option would be to split the stack over two devices: one for Elasticsearch and Kibana, and another one for the Logstash service
  2. Elastic has no builds for Raspbian. Hence, in the instructions below, I will use Debian packages and will describe the steps to install those on the Pi. This will require some custom configs and scripts, so be prepared for that. Well, this article is how to hack the installation and no warranties are provided 🙂
  3. You will not be able to use the ML functionality of Elasticsearch because it is not supported on the low-powered Raspbian device
  4. Below steps assume version 7.7.0 of the ELK stack. If you are installing a different version, make sure that you replace it accordingly in the commands below
  5. Last but not least (in the spirit of no warranties), Elasticsearch has a dependency on libc6that will be ignored and will break future updates. You have to deal with this at your own risk

Here the steps to follow.

Installing Elasticsearch on Raspberry Pi

  1. Set up your Raspberry Pi first. Here are the steps to set up your Rasberry Pi. The Raspberry Pi Imager makes it even easier to set up the OS. Once again, I would recommend using Raspberry Pi 4 Model B Quad Core 64 Bit with 4GB[ad] and a larger SD card[ad] to save logs for longer.
  2. Make sure all packages are up to date, and your Raspbian OS is fully patched. 
    sudo apt-get update
sudo apt-get upgrade
  3. Install the ZIP utility, we will need that later on for the Logstash configuration. 
    sudo apt-get install zip
  4. Then, install the Java JRE because Elastic Stack requires it. You can use the open-source JRE to avoid licensing troubles with Oracle’s one. 
    sudo apt-get install default-jre
  5. Once this is done, go ahead and download the Debian package for Elasticsearch. Make sure that you download the package with no JDK in it. 
    wget https://artifacts.elastic.co/downloads/elasticsearch/elasticsearch-7.7.0-no-jdk-amd64.deb
  6. Once this is done, go ahead and install Elasticsearch using the package manager. 
    sudo dpkg -i --force-all --ignore-depends=libc6 elasticsearch-7.7.0-no-jdk-amd64.deb
  7. Next, we need to configure Elasticsearch to use the installed JDK. 
    sudo vi /etc/default/elasticsearch

    Set the JAVA_HOMEto the location of the JDK. Normally this is /usr/lib/jvm/default-java. You can also set the JAVA_HOMEto the same path in the /etc/environmentfile but this is not required.

  8. Last thing you need to do if to disable the ML XPack for Elasticsearch. Change the access mode to the /etc/elasticsearchdirectory first and edit the Elasticsearch configuration file. 
    sudo chmod g+w /etc/elasticsearch
sudo vi /etc/elasticsearch/elasticsearch.yml

    Change the xpack.ml.enabledsetting to falseas follows:

    xpack.ml.enabled: false

The above steps install and configure the Elasticsearch service on your Raspberry Pi. You can start the service with:

sudo service elasticsearch start

Or check its status with:

sudo service elasticsearch status

Installing Logstash on Raspberry Pi

Installing Logstash on the Raspberry Pi turned out to be a bit more problematic than Elasticsearch. Again, Elastic doesn’t have a Logstash package that targets ARM architecture and you need to install it manually. StackOverflow posts and GitHub issues were particularly helpful for that – I listed the two I used in the References at the end of this article. Here the steps:

  1. Download the Logstash Debian package from Elastic’s repository. 
    wget https://artifacts.elastic.co/downloads/logstash/logstash-7.7.0.deb
  2. Install the downloaded package using the dpkg package installer. 
    sudo dpkg -i logstash-7.7.0.deb
  3. If you run Logstash at this point and encounter error similar to logstash load error: ffi/ffi -- java.lang.NullPointerException: null get Alexandre Alouit’s fix from GitHub using. 
    wget https://gist.githubusercontent.com/toddysm/6b4b9c63f32a3dfc476a725561fc23af/raw/06a2409df3eba5054d7266a8227b991a87837407/fix.sh
  4. Go to /usr/share/logstash/logstash-core/lib/jars and check the version of the jruby-complete-X.X.X.X.jarJAR
  5. Open the downloaded fix.sh, and replace the version of the jruby-complete-X.X.X.X.jaron line 11 with the one from your distribution. In my case, that was  jruby-complete-9.2.11.1.jar
  6. Change the permissions of the downloaded fix.shscript, and run it. 
    chmod 755 fix.sh
sudo ./fix.sh
  7. You can run Logstash with. 
    sudo service logstash start

You can check the Logstash logs in /var/log/logstash/logstash-plain.logfor information on whether Logstash is successfully started.

Installing Kibana on Raspberry Pi

Installing Kibana had different challenges. The problem is that Kibana requires an older version of NodeJS, but the one that is packed with the Debian package doesn’t run on Raspbian. What you need to do is to replace the NodeJS version after you install the Debian package. Here the steps:

  1. Download the Kinabna Debian package from Elastic’s repository. 
    wget https://artifacts.elastic.co/downloads/kibana/kibana-7.7.0-amd64.deb
  2. Install the downloaded package using the dpkg package installer. 
    sudo dpkg -i --force-all kibana-7.7.0-amd64.deb
  3. Move the redistributed NodeJS to another folder (or delete it completely) and create a new empty directory nodein the Kibana installation directory. 
    sudo mv /usr/share/kibana/node /usr/share/kibana/node.OLD
sudo mkdir /usr/share/kibana/node
  4. Next, download version 10.19.0 of NodeJS. This is the required version of NodeJS for Kibana 7.7.0. If you are installing another version of Kibana, you may want to check what NodeJS version it requires. The best way to do that is to start the Kibana service and it will tell you. 
    wget https://nodejs.org/download/release/v10.19.0/node-v10.19.0-linux-armv7l.tar.xz
  5. Unpack the TAR and move the content to the nodedirectory under the Kibana installation directory. 
    sudo tar -xJvf node-v10.19.0-linux-armv7l.tar.xz
sudo mv ./node-v10.19.0-linux-armv7l.tar.xz/* /usr/share/kibana/node
  6. You may also want to create symlinks for the NodeJS executable and its tools. 
    sudo ln -s /usr/share/kibana/node/bin/node /usr/bin/node
sudo ln -s /usr/share/kibana/node/bin/npm /usr/bin/npm
sudo ln -s /usr/share/kibana/node/bin/npx /usr/bin/npx
  7. Configure Kibana to accept requests on any IP address on the device. 
    sudo vi /etc/kibana/kibana.yml

    Set the server.hostsetting to 0.0.0.0like this:

    server.host: "0.0.0.0"
  8. You can run Kibana with. 
    sudo service kibana start

Conclusion

Although not supported, you can run the complete ELK stack on a Raspberry Pi 4[ad] device. It is not the most trivial installation, but it is not so hard either. In the following posts, I will explain how you can use the Elastic SIEM to monitor the traffic on your network.

References

Here are some additional links that you may find useful: