Is it possible to use the public network, namely Internet, to make 2 machines communicate securely ? And if possible something easier to install and configure than OpenVpn ?
A few months ago, I heard about Nebula from Defined and wanted to test it : one single binary, some certificates and as secure as it can be, that sounded promising !
So here we are trying to simulate a mesh network between 2 virtual machines using Vagrant on my Ubuntu Linux distribution 20.04 with Virtualbox already installed.
Vagrant
Vagrant from Hashicorp is the tool I use to manage virtual machines.
sudo apt install -y vagrant
I configure Vagrant to have 2 virtual machines with Debian 11, named respectively boxA and boxB.
To make it simple, I use my host network interface to link the 2 virtual machines (so eth0
in my case) and use the available DHCP of my local network.
cat <<EOF > Vagrantfile
Vagrant.configure("2") do |config|
config.vm.define "boxA" do |boxA|
boxA.vm.box = "generic/debian11"
boxA.vm.network "public_network", bridge: "eth0"
end
config.vm.define "boxB" do |boxB|
boxB.vm.box = "generic/debian11"
boxB.vm.network "public_network", bridge: "eth0"
end
end
EOF
Now I can launch the 2 machines with a single command :
vagrant up
Nebula
Installing nebula is as simple as downloading the binaries from github. I choose nebula-linux-amd64.tar.gz
to comply to my configuration.
wget https://github.com/slackhq/nebula/releases/download/v1.6.0/nebula-linux-amd64.tar.gz
After downloading, I uncompress the archive :
tar xf nebula-linux-amd64.tar.gz
I now have 2 binaries : nebula and nebula-cert.
-
nebula
will be copied on the 2 virtual machines. This is the main binary who will establish the bridge between the machines. -
nebula-cert
will be used to generate all needed certificates :
./nebula-cert ca -name "ACME, Inc"
./nebula-cert sign -name "boxA" -ip "192.168.168.100/24"
./nebula-cert sign -name "boxB" -ip "192.168.168.200/24"
I choose 192.168.168.*
as my mesh network IP addresses : .100 for boxA and .200 for boxB.
The results of the commands are this list of files :
ca.crt
ca.key
boxA.crt
boxA.key
boxB.crt
boxB.key
To make it more simple to copy the files to the virtual machines, I create a folder per machine and copy the needed files :
mkdir boxA boxB
mv boxA.* boxA && mv boxB.* boxB
Now I want to generate a Nebula configuration file, that will be common for the 2 machines. I need to get their IP addresses on my local network (those assigned by my DHCP server). I know that vagrant will use the eth1 interface inside the machines, so I use some magic shell script :
First on boxA :
boxAip=$(vagrant ssh boxA --no-tty -c "ip address show eth1| grep 'inet ' | sed -e 's/^.*inet //' -e 's/\/.*$//'" | tr -d '\r')
Then on boxB :
boxBip=$(vagrant ssh boxB --no-tty -c "ip address show eth1| grep 'inet ' | sed -e 's/^.*inet //' -e 's/\/.*$//'" | tr -d '\r')
The magic is that $boxAip
and $boxBip
variables now contain the wanted IPs. Let use them inside the Nebula config in the static_host_map
section :
cat <<EOF > config.yml
pki:
ca: /etc/nebula/ca.crt
cert: /etc/nebula/host.crt
key: /etc/nebula/host.key
static_host_map:
"192.168.168.100": ["$boxAip:4242"]
"192.168.168.200": ["$boxBip:4242"]
lighthouse:
am_lighthouse: false
listen:
host: 0.0.0.0
port: 4242
punchy:
punch: true
tun:
disabled: false
dev: nebula1
drop_local_broadcast: false
drop_multicast: false
tx_queue: 500
mtu: 1300
routes:
unsafe_routes:
logging:
level: info
format: text
firewall:
conntrack:
tcp_timeout: 12m
udp_timeout: 3m
default_timeout: 10m
max_connections: 100000
outbound:
- port: any
proto: any
host: any
inbound:
- port: any
proto: any
host: any
EOF
It's time to configure the machines. First, let send all the files to each machine :
vagrant upload ./boxA /tmp/ boxA
vagrant upload ./boxB /tmp/ boxB
vagrant upload ca.crt /tmp/ boxA
vagrant upload ca.crt /tmp/ boxB
vagrant upload config.yml /tmp/ boxA
vagrant upload config.yml /tmp/ boxB
vagrant upload nebula /tmp/ boxA
vagrant upload nebula /tmp/ boxB
Now I ssh in each machine and continue the configuration :
First, boxA :
vagrant ssh boxA
Inside boxA, I move the files in their respective location and finally launch Nebula in the background before quitting boxA :
sudo mkdir /etc/nebula
sudo mv /tmp/config.yml /etc/nebula/config.yml
sudo mv /tmp/ca.crt /etc/nebula/ca.crt
sudo mv /tmp/boxA.crt /etc/nebula/host.crt
sudo mv /tmp/boxA.key /etc/nebula/host.key
sudo mkdir /opt/nebula
sudo mv /tmp/nebula /opt/nebula/
chmod +x /opt/nebula/nebula
cd /opt/nebula
sudo ./nebula -config /etc/nebula/config.yml &
exit
Let's configure boxB,
vagrant ssh boxB
Then I move all files and launch Nebula :
sudo mkdir /etc/nebula
sudo mv /tmp/config.yml /etc/nebula/config.yml
sudo mv /tmp/ca.crt /etc/nebula/ca.crt
sudo mv /tmp/boxB.crt /etc/nebula/host.crt
sudo mv /tmp/boxB.key /etc/nebula/host.key
sudo mkdir /opt/nebula
sudo mv /tmp/nebula /opt/nebula/
chmod +x /opt/nebula/nebula
cd /opt/nebula
sudo ./nebula -config /etc/nebula/config.yml &
exit
Ok, at this moment, I have 2 virtual machines, with a Nebula network between them. How am I going to verify that it is really working ?
Well if I can ping boxB from boxA, it will mean that all is ok, so let's found out :
vagrant ssh boxA -c "ping 192.168.168.200"
Hourra ! It is working. Of course, I can do it on the other side :
vagrant ssh boxB -c "ping 192.168.168.100"
And that's all folks for part 1 !
Next, I'll try to use this configuration to execute a MySQL server on one machine, and access it from a MySQL client on the other machine. And to make it a little more difficult, I'll use Podman as the container engine to execute this client and server.
See Part 2
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