Ubuntu Linux and OpenVPN Client, using UFW to force traffic via VPN tunnel interface

Updated 24/07/17; included startup configuration to ensure automatic docker container connectivity via VPN post reboot/ startup.

First, you’ll need to obtain your “.ovpn” configuration file from your VPN provider. Find and replace <config file> with the name of the file excluding the file extension.

There are two stages to this guide:

  1. VPN Client Connection/ Configuration
  2. UFW Firewall Configuration (to ensure traffic can only use VPN and prevent DNS Leak)

If you are using docker containers be sure to check the considerations at the end of this article.

VPN Client Connection/ Configuration

Prepare the configuration file:

# Disable IPv6
echo "#disable ipv6" | sudo tee -a /etc/sysctl.conf
echo "net.ipv6.conf.all.disable_ipv6 = 1" | sudo tee -a /etc/sysctl.conf
echo "net.ipv6.conf.default.disable_ipv6 = 1" | sudo tee -a /etc/sysctl.conf
echo "net.ipv6.conf.lo.disable_ipv6 = 1" | sudo tee -a /etc/sysctl.conf
sudo sysctl -p

# Move config file to /etc/openvpn
mv <config file>.ovpn /etc/openvpn/<config file>.conf

# Create .secrets file
echo '<username>' >> /etc/openvpn/.secrets
echo '<password>' >> /etc/openvpn/.secrets
chmod 600 /etc/openvpn/.secrets

# Modify config file
vi <config file>.conf

# Ensure you have no other auth-user-pass lines defined
auth-user-pass .secrets

# Add redirect-gateway to force traffic down TUN interface

# Add DNS server update script execution to config file
script-security 2
up /etc/openvpn/update-resolv-conf
down /etc/openvpn/update-resolv-conf

# Save/close config file

We’ll now configure OpenVPN client to automatically connect to this VPN interface on startup:

# Edit /etc/default/openvpn, un-comment AUTOSTART="all" then save/close 
vi /etc/default/openvpn

# Start / enable openvpn service at boot
sudo systemctl start openvpn
sudo systemctl enable openvpn

Confirm the VPN tunnel is up and public IP is that of the VPN provider:

# Look for a tun0 interface, if found you are connected!

# Check public IP is "hidden"/ different vs. machine not on the VPN
curl ipinfo.io/ip

UFW Firewall Configuration

We’ll configure UFW to allow only allow outbound traffic to the VPN provider (“tun0” in this example) interface.

First we must enable forwarding:

vi /etc/default/ufw

Next we’ll configure the necessary UFW rules to facilitate the outbound traffic to the VPN provider, but block everything else. You’ll need to change:

  • <VPN Server IP> to IPv4 address as-per the “remote xx.xx.xx.xx” line in your OpenVPN configuration file.
  • <port> to the remote OpenVPN port  (usually 1194 or 443)
  • <LAN subnet> to network/subnet that represents your network – i.e.
# Defaults
ufw default deny incoming
ufw default deny outgoing

# Allow SSH from local LAN
ufw allow from <LAN subnet> to any port 22

# UFW rule to ensure we only hit the VPN
ufw allow out to <VPN server IP> port <VPN server port>
ufw allow out to <LAN subnet>
ufw allow out on tun0

# Enable the firewall
ufw enable

If DNS lookups on the client fail you’ve missed the configuration lines from your OpenVPN configuration file, as above, you want to force DNS lookups over the VPN otherwise you’re leaking DNS requests, reducing the privacy value of your VPN.

# Add DNS server update script execution to config file 
script-security 2 
up /etc/openvpn/update-resolv-conf 
down /etc/openvpn/update-resolv-conf

Considerations when using Docker Containers

If you want your docker containers to sit behind the VPN, ensure you use the–net=host” argument. As per: https://docs.docker.com/engine/userguide/networking/default_network/container-communication/

If your containers have no internet connectivity at startup it is likely because docker started before the VPN connection was established. Credits for this solution here.

sudo mkdir /etc/systemd/system/docker.service.d/
sudo touch /etc/systemd/system/docker.service.d/depend.conf
sudo vi /etc/systemd/system/docker.service.d/depend.conf

# New conf file should only contain lines below

# Now save the file and exit vim

sudo systemctl daemon-reload

# Test container connectivity following a reboot

Docker’s forward rules permit all external source IPs by default.

By default containers will use the docker0 interface and thus when your VPN goes down, they will still have external/ internet access. This statement only applies when using the default docker0 interface, not when binding the container to the “host” interface.

My experience shows that the default docker forward rule associated with the docker0 interface  overrides any UFW rule (i.e. as defined above).

You can test container connectivity using the commands below:

# Test there is NO connectivity from container when VPN is down
systemctl stop openvpn
docker exec -it <container_name> /bin/bash

# Test this IS connectivity from container when VPN is up
systemctl start openvpn
docker exec -it <container_name> /bin/bash

Running guacamole from a Docker Container on Ubuntu 16.04 LTS / 16.10

Updated Feb 2017 to reflect guacamole/guacd and guacamole/guacamole Docker images, rather than the glyptond images.

Updated 26/05/17 to include Tomcat hardening, as-per https://www.owasp.org/index.php/Securing_tomcat

Want to get multi-factor authentication? Check out my post here for Docker support/ deployment of Duo MFA for Guacamole.

I’ve been looking at how I can move some/ all of my QEMU virtualised workloads to docker containers – the main drivers behind this being:

  • Reducing the administrative overhead of updating an additional operating system
  • Reducing the compute overhead of running an additional operating system on top of the host O/S

I also looked at whether this solution wold run in a docker-enabled Ubuntu 16.04 LXD container and, whilst the mysql and guacamole images downloded, the guacd image failed with an “operation not permitted error” meaning I was unable to use the image inside an LXD container.

I use Apache guacamole for remote access to my infrastructure and, on finding there were guacamole containers for the client and server elements, I thought I would look to move this workload from a dedicated Ubuntu Server 16.04 LTS Virtual Machine to a docker container.

This guide assumes you have installed docker as outlined here: http://www.cb-net.co.uk/linux/installing-docker-on-ubuntu-16-04-lts-16-10/

Downloading / Deploying the Container

Be sure to define/ update the commands below with:

  • A new mysql root user password (find and replace <root password> )
  • A new mysql guacamole user password (find and replace <guac user password> )

We will now create/ configure and start three containers:

  1. A mysql database instance: guac-mysql
  2. A guacamole-server container: guacd
  3. A guacamole-client container: guacamole
# Pull the guacamole (and related) docker images
sudo docker pull guacamole/guacd
sudo docker pull guacamole/guacamole
sudo docker pull mysql 

# Create script to prepare MySQL Database
docker run --rm guacamole/guacamole /opt/guacamole/bin/initdb.sh --mysql > initdb.sql

# Make a scripts folder to pass-through to container
mkdir /tmp/scripts
cp initdb.sql /tmp/scripts

# Create/ start mysql instance
docker run --name guac-mysql -v /tmp/scripts:/tmp/scripts -e MYSQL_ROOT_PASSWORD=<root password> -d mysql:latest 
history -c

# Create mysql db, user and prepare mysql instance for guacamole
docker exec -it guac-mysql /bin/bash

mysql -u root -p'<root password>'
CREATE USER 'guacamole' IDENTIFIED BY '<guac user password>';

cat /tmp/scripts/initdb.sql | mysql -u root -p'<root password>' guacamole
history -c

# Now ctrl-d to exit docker container shell

# Start guacd 
docker run --name guacd -d guacamole/guacd

# Start guacamole client
docker run --name guacamole --link guacd:guacd --link guac-mysql:mysql \
-e MYSQL_DATABASE='guacamole' \
-e MYSQL_USER='guacamole' \
-e MYSQL_PASSWORD='<guac user password>' \
-d -p 8080:8080 guacamole/guacamole

# Harden tomcat, as-per https://www.owasp.org/index.php/Securing_tomcat
sudo docker exec -it guacamole /bin/bash

sed -i 's/redirectPort="8443"/redirectPort="8443" server="" secure="true"/g' /usr/local/tomcat/conf/server.xml

sed -i 's/<Server port="8005" shutdown="SHUTDOWN">/<Server port="-1" shutdown="SHUTDOWN">/g' /usr/local/tomcat/conf/server.xml
rm -Rf /usr/local/tomcat/webapps/docs/
rm -Rf /usr/local/tomcat/webapps/examples/
rm -Rf /usr/local/tomcat/webapps/manager/
rm -Rf /usr/local/tomcat/webapps/host-manager/
chmod -R 400 /usr/local/tomcat/conf

You can now browse to http://<docker host IP>:8080/guacamole/ and login using the credentials guacadmin/guacadmin.

Managing the Containers

Replace “guac-mysql” below with the other container names used above to manage guacd, guacamole or guac-mysql independently:

# Start a container
sudo docker start guac-mysql
# Stop a container
sudo docker stop guac-mysql
# Hard-stop a container
sudo docker kill guac-mysql
# Restart (and auto-update) a container
sudo docker restart guac-mysql
# List all running containers
sudo docker ps
# List all running AND non-running containers
sudo docker ps -a
# Remove a container
sudo docker rm guac-mysql
# Remove the mysql docker image
sudo docker rmi mysql
# Review logs for container
sudo docker logs -f guac-mysql

Running Plex from a Docker Container on Ubuntu 16.04 LTS / 16.10

Updated 24/12/16 : Plex now have an official Docker container, this guide has been updated to use this.

Updated 28/03/17 : Automatic updates not working on your container when restarting? Make sure you specify the correct tag for the docker image. If you are a plexpass subscriber pull the “plexinc/pms-docker:plexpass” image, if not pull the “plexinc/pms-docker:public” image.

Updated 22/05/17: Issue with NFS volumes not being mounted when docker service started led to media being unavailable without container/ docker restart. Changing volumes passed-through to container to include “:shared” resolves this issue.

I’ve been looking at the merits of moving my Plex server workload from a dedicated KVM/QEMU virtual machine to a docker container on the host server itself. The reasons for doing this were as below:

  • Reducing the administrative overhead of updating an additional operating system
  • Reducing the compute overhead of running an additional operating system on top of the host O/S

An additional benefit of running Plex in this manner is that on restarting the container the latest version of Plex is automatically pulled and deployed, making updates in future very, very simple.

This guide assumes you have installed docker as outlined here: http://www.cb-net.co.uk/linux/installing-docker-on-ubuntu-16-04-lts-16-10/

Downloading / Deploying the Container

To download and deploy the container you will need:

  • A storage location for the Plex configuration directory – this is persistent, i.e. it will survive containers being deleted/ recreated. The size of this will vary based on how large your media library is. On libraries with several terabytes of media you looking at tens of gigabytes of storage.
  • One or multiple mount points/ folder locations that contains your media (in this example there are multiple “-v” definitions that represent paths to TV shows, movies etc. you can have as many of these as you want)

Note below, I have used the “plexinc/pms-docker:plexpass” docker image to ensure automatic updates on container restart work. If you are not a plexpass subscriber ensure you change this to “public.” If you do not specify a tag, automatic updates on the container will not work.

# Pull the linuxserver/plex docker image
sudo docker pull plexinc/pms-docker:plexpass

# Get a Plex Claim Token by going to this URL and replace <CLAIM> below
# https://www.plex.tv/claim/

# Create a new linuxserver/plex docker container
docker create \
--name plex \
--net=host \
-e TZ=Europe/London \
-e PUID=1000 -e PGID=1000 \
-v <path to config>:/config \
-v <path to music>:/data/music:shared \
-v <path to tv series>:/data/tvshows:shared \
-v <path to movies>:/data/movies:shared \
-v <path to home videos>:/data/homevideos:shared \

# Configure docker container to always update
docker update --restart=always plex

# Start the plex container
docker start plex

You’ll notice I have defined volumes as “:shared” which enables NFS volumes passed-through to the container to be mounted after the container starts without issue.

You can now browse to http://<docker host IP>:32400 and login using you plex.tv account.

If you want to use the PlexPass version of Plex modify the server settings and restart the container using the command shown below.

Managing the Plex Container

# Start the plex container
sudo docker start plex
# Stop the plex container
sudo docker stop plex
# Hard-stop the plex container
sudo docker kill plex
# Restart (and auto-update) the plex container
sudo docker restart plex
# List all running containers
sudo docker ps
# List all running AND non-running containers
sudo docker ps -a
# Remove the plex container (note you can redploy and will not lose anything/ config wise)
sudo docker rm plex
# Remove the linuxserver/plex docker image
sudo docker rmi linuxserver/plex
# Review logs for plex container
sudo docker logs -f plex

Installing Docker on Ubuntu Server 16.04 LTS / 16.10

I’ve been looking at moving some of my application/ process workloads from KVM/ QEMU Virtual Machines to docker containers – simply to reduce unnecessary overhead and complexity.

Installing docker on Ubuntu Server 16.04 or 16.10 is surprisingly straight-forwards, it is also possible (from my experience) to run docker alongside KVM/QEMU on the host server, as well as running docker containers within KVM/QEMU virtual machines.

# Update host O/S
sudo apt-get update
sudo apt-get install apt-transport-https ca-certificates

# Create apt source for docker
sudo apt-key adv \
--keyserver hkp://ha.pool.sks-keyservers.net:80 \
--recv-keys 58118E89F3A912897C070ADBF76221572C52609D 
echo "deb https://apt.dockerproject.org/repo ubuntu-xenial main" | sudo tee /etc/apt/sources.list.d/docker.list

# Pre-reqs installation
sudo apt-get update
sudo apt-get install linux-image-extra-$(uname -r) linux-image-extra-virtual

# Install docker
sudo apt-get update
sudo apt-get install docker-engine
sudo service docker start

# UFW config
sudo ufw status

# If UFW enabled modify /etc/default/ufw
vi /etc/default/ufw

# Set docker to start on boot
sudo systemctl enable docker

Changing the guacamole MySQL User Password

From an SSH shell execute the following commands to change the MySQL user password:

mysql -u root -h localhost -p'<root password>'
USE guacamole;
SET PASSWORD FOR 'guacamole'@'localhost' = PASSWORD('<new password>');

Now modify /etc/guacamole/guacamole.properties ensuring you update the value for “mysql-password: <password>”

# MySQL properties
mysql-hostname: localhost
mysql-port: 3306
mysql-database: guacamole
mysql-username: guacamole
mysql-password: <password>

Finally restart tomcat8

systemctl restart tomcat8