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Archive → December, 2011

VPN (IPsec) tunnel between a pfSense 2.0 router and a FRITZ!Box

We have a pfSense 2.0 router at our coworking space which is hooked up to a pretty fast VDSL line so I thought it would be a fun idea to connect my home network (where I’m using a FRITZ!Box 7390) to the work LAN using a secure and permenent VPN tunnel.

Doing a quick Google search yields results for the 1.2 version of pfSense which is outdated and does not use DynDNS hostnames for both ends, so I did a quick writeup of my own.


First things first, create permanent hostnames for your pfSense and your FRITZ!Box. If your DSL provider has assigned permanent IP addresses, that’s fine. If they didn’t you’ll probably need something like DynDNS. Last time I checked, you could still get free accounts, otherwise it’s just a few bucks a year – probably a good investment. You’ll need to configure both the pfSense and the FRITZ!Box to update your DynDNS hosts whenever their IP address changes, but that’s pretty straight forward so I won’t cover it here. Fun fact: you can add CNAME records to your company domain pointing to your DynDNS host, so it looks even more professional. We use vpn.launchco.com for instance – how cool is that?

You’ll also need two different primary subnets for your networks, i.e. if your home network lives in, which is the standard network a FRITZ!Box uses, your work network has to use something else, like, which is by the way the standard that pfSense uses – so you should be safe if you’re like me a big fan of sticking with sensible vendor defaults.

Now, with the permanent hostnames and subnets in place, let’s get down to business.

Setting up pfSense

We’re using IPsec, so let’s head to VPN -> IPsec first and click the [+] icon on the bottom right to add a new phase 1 entry.

Fill the form in accordance to what you see on the following screenshot:

Screenshot of pfSense configuration phase 1 entry

Obviously, replace your-fritz.dyndns.org with the permanent hostname assigned to your FRITZ!Box as well as your-pfsense.dyndns.org with the one on your pfSense box. The Pre-Shared Key should be a long random string. Don’t worry, you won’t have to remember it. You’ll just save that in the FRITZ!Box later and then you can forget about it.

Next up, we need a phase 2 entry. For that, click the [+] icon next to a label that says Show 0 Phase-2 entries and fill the form like below:

Screenshot of pfSense configuration phase 2 entry

Here, you just need to make sure that you replace with the actual subnet your FRITZ!Box uses. Again, if you’ve sticked with the default when setting up the box, this setting should be right for you.

That should be it for the pfSense. After saving it’ll probably ask you to apply or reload the configuration. This is safe to do now.

Setting up the FRITZ!Box

Now, let’s finish this by configuring a VPN entry in your FRITZ!Box. From my perspective, this part is much easier, because I’m just pasting code instead of fiddling with screenshots – yay!

Fire up your favorite text editor and paste the following code:

Make the necessary modifications according to the comments in the file. Then, open the FRITZ!Box configuration interface in your browser and head to Internet -> Freigaben -> VPN, use the browse button to select the file you just created and click on VPN-Einstellungen importieren.

That’s it – you’re done. In my first trials I had to go back to the pfSense interface and navigate to Status -> IPsec to click on a small [>] (“play”) button to get things rolling. Maybe you need this, maybe it just works without it.

Getting the connection up after a restart of either of the two routers sometimes fails which is most probably due to the fact that DynDNS updates have not yet propagated when the VPN tries to connect. In this case, just be patient; both boxes will keep retrying to open VPN connections and you can always stop/start on both ends yourself. Once a connection is made, the tunnels are usually stable and rock-solid. Enjoy!