Simple install of OpenVPN with Ubuntu server and Mint client

Since I’ll have my laptop and phone with me while I’m in hospital, I’m expecting to be able to keep in touch with family and friends. However, it would also be useful to have access to my home network from hospital. I can already SSH into a command line on my home server, but I’ve been meaning to get a proper VPN set up for some time now, so this seemed like the excuse I needed to actually make it happen.

In my case, I have a home network with a NAT’d router that has a static IP address, and proper DNS & reverse DNS entries associated with it. I then have an Ubuntu Server running 24×7 behind it, providing various services to my home network. I simply want my Mint laptop to be able to VPN into my home network, securely, and on demand.

It turns out to be really straighforward, though there were a few quirks to overcome! Fundamentally I followed the instructions in this PDF to set up the server side of the VPN, found on the Madison Linux User Group website. However, there are a few problems with it, that need correcting:

  1. Under “Installing the Network Bridge and Configure Network Settings” on page 3, be aware that if you are using dnsmasq to mange your DNS and DHCP leases, you will need to change it’s configuration file in /etc/dnsmasq.conf, to listen on br0 rather than eth0.
  2. Under “Create the Server Keys and Certificates”, point (3), note that there are two KEY_EMAIL variables where there should be only one, and the variables KEY_CN, KEY_NAME and KEY_OU should ideally be filled in for completeness.
  3. Under “Create the Server Keys and Certificates”, before starting on point (4), you (a) need to edit the file /etc/openvpn/easy-rsa/whichopensslcnf, and remove all occurances of the string “[[:alnum:]]”, and (b) need to make sure that you can write to the file “~/.rnd”; by default it isn’t writeable except by root, so you need to issue the command “sudo chown youruserid ~/.rnd”.
  4. Under “Generate the Client Keys and Certificates” on page 4, when you come to carry out the instructions in point (1), to create the client keys, you must set a unique KEY_CN by changing the last command to something like “KEY_CN=someuniqueclientcn ./pkitool client1”.
  5. Under “Create the OpenVPN Server Scripts”, on page 5, the code to go into the up.sh and down.sh scripts is wrong. The brctl command is located in /sbin, not /usr/sbin. Change both scripts accordingly.

For the client side of the VPN, I followed the instructions in this PDF, which worked perfectly.

Once everything has been rebooted and is working properly, it is possible to VPN into my home network from the internet. All traffic from my laptop then flows through my home network via a secure VPN. Essentially my laptop becomes part of my home network for the time the VPN is running.

Which is exactly what I wanted.

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