Recently one of my students asked for a recommendation on a VPN app for his Macbook. I thought my rather long-winded reply might be useful to others wondering the same thing, and it’s appended below.
There are two primary use cases for a VPN:
- You are away from your home network, possibly on an unsecured network such as in a café or an airport, and want to encrypt all of the network traffic coming to and from your computer (even traffic that isn’t normally encrypted)
- You want to appear to be somewhere else in the world. I ran into this when I wanted to watch World Cup soccer matches not shown in the US but available in the UK; I set up a VPN connection to a server in London so that it appeared I was in that city, and then watched the games on the BBC.
Here’s my reply to my student’s question:
The short answer is that I don’t trust the apps on the App Store for VPNs. The longer reason…all of them provide their own server to connect to, which means that my VPN internet traffic is going through an endpoint that I don’t control. The only assurance I have that my traffic isn’t being decrypted, stored, or otherwise manipulated is that the app seller tells me that they don’t. Also, the programs are not open source, so I can’t look through the code to assure myself that there is no back door or other security risk.
For that reason, I use Tunnelblick on the Mac (https://tunnelblick.net), which is an open-source VPN program. I have very high confidence that it hasn’t been compromised. I run my own VPN server (which I personally built and maintain) to connect Tunnelblick to when I’m away from the home network, so the encrypted tunnel goes from my Macbook, through the Tunnelblick VPN, into my own server, and from there out onto the internet. The use case is typically that I’m away from home, on an insecure network, and want to lock down / encrypt everything going over that network.
That being said, if my purpose is to connect to a VPN so that it appears I am somewhere else, such as if I want my internet address to be in the UK to watch soccer, I’m forced to use one of the commercial VPN providers, and for that I use Tunnelbear, https://www.tunnelbear.com. Note that this is not open-source, and so your confidence in it in terms of privacy should be very low. They do get good reviews, and I’ve had a $5/month subscription with them for about three years now. I generally use Tunnelbear for very specific purposes (such as location shifting) and take steps to make sure that no other traffic is going through their VPN endpoint (I use Little Snitch firewall rules to accomplish this).
On the iPhone/iPad side I use OpenVPN (https://openvpn.net), but again I’m connecting back to my on VPN server with it. It’s an open-source project that I have high confidence in.
OpenVPN offers PrivateTunnel, with a pay-as-you-go connection plan that is fairly inexpensive. It’s the same team that produces OpenVPN, so I would trust them a little more. The ‘tunnel’ is a VPN connection back to one of their servers, and so you run the same risk of interception as with something like TunnelBear, which means that you would NOT use this solution for highly sensitive traffic. Also, I don’t believe that they have all that many servers, so you’d be limited in your choice of where you appear to be. I’ve been meaning to give them a try to see what the service looks like.
[update 7/15/2016] I’ve installed Private Tunnel for testing. They offer endpoints in: NYC; Chicago; Miami; San Jose; Montreal; London; Amsterdam; Stockholm; Frankfurt; Tokyo; Zurich; and Hong Kong.
I know that’s a long answer! Bottom line is that if you are connecting to someone else’s VPN server, don’t trust it with anything other than mundane traffic. For location-shifting to do something trivial like watch soccer or get around a school’s firewall, commercial solutions like TunnelBear are fine.
Since we’re on the subject, I can’t recall if I mentioned it in class, but if you need secure IM and voice, you (currently) should be using Signal and nothing else. And of course PGP for email :^)