Tag Archives: OpenVPN

Creating OpenVPN .ovpn Files for Android (Any?) Clients

In another post I cover setting up and OpenVPN server on a Tomato powered router and making client connections to that server.

In setting up a new phone, I see the OpenVPN for Android app will now import yourVPNclient.ovpn files (much easier than transferring and importing the separate key and cert components as covered in my prior post). It took a bit of Googling to find out how to create the .ovpn files, but now that I’ve found the file format, setting one up turns out to be a piece of cake. Here’s the template:


client
proto udp
remote your.openvpnserver.url.net
port 1194
dev tun
nobind

key-direction 1

<ca>
-----BEGIN CERTIFICATE-----
# insert base64 blob from ca.crt
-----END CERTIFICATE-----
</ca>

<cert>
-----BEGIN CERTIFICATE-----
# insert base64 blob from client1.crt
-----END CERTIFICATE-----
</cert>

<key>
-----BEGIN PRIVATE KEY-----
# insert base64 blob from client1.key
-----END PRIVATE KEY-----
</key>

<tls-auth>
-----BEGIN OpenVPN Static key V1-----
# insert ta.key
-----END OpenVPN Static key V1-----
</tls-auth>

I edited the “remote” directive to point to my VPN (router’s) dynamic DNS address and then copied the specified parts of the files from the /etc/openvpn directory as created in my prior post to this template. Then saved the consolidated file as myserver+clientname.ovpn.txt on my linux box.

Why with *.txt extension? Because otherwise the bluetooth file transfer from my desktop linux box to my phone would fail (unsupported file type). Text file transfer is supported, .ovpn is apparently not.

I then simply renamed the file on my Android phone to drop the .txt suffix and imported the resulting file in the OpenVPN for Android app (it turns out you can leave it, but the app will include that text in the connection name by default, so I now simply cut it there). I still needed to go through and set some options properly in the app to match my server config (LZO, persistent TUN, etc.), but the heavy lifting was already done.

Connected successfully on my first try! I see no reason why the same file set up would not work in NetworkManager on Linux or some other client, but I haven’t tried myself. Good luck!

Credit for the .ovpn template content goes to this ServerFault discussion thread .

QR Codes as a Password/Key Storage Mechanism

I was doing some recent volunteer work for the Concord Scout House, Inc., setting up a new network and telephony infrastructure for this non-profit enterprise. In setting up the various pieces of equipment, I was sure to create strong passwords and use key and certificate based encryption or similar security mechanisms in order to keep things secure.

Of course, I kept copies for my own records in a suitable electronic format (I personally do local plus encrypted cloud backups of critical files via Spider Oak). As this is a volunteer job, it is very possible someone else will need to do something with this infrastructure at a later point – when I may no longer be involved with the organization. This left me with the problem of how to document and pass on those passwords and keys in a convenient and durable fashion to those who may follow.

I could prepare a DVD or flash drive with the passwords and keys, etc. in simple text files to hand over. This could work fine but also quickly fall prey to changes in applications or operating systems (e.g.: Wordpad or vi? Unix or DOS line feeds?), hardware technology (how many Android phones have a DVD reader? will USB2/3 ports be usable in 10 years?) or simple hardware failure (scratched DVD). For convenience’s sake, I will provide a soft copy on DVD (as that may be stored easily in a file folder) but there’s one medium all organizations still know how to deal with and store safely: paper.

I could simply print out the passwords and certificates/keys as plain text on sheets of paper, but then someone trying to use it would have to accurately type in that text at a later point where/when required. As we’re talking 100+ characters in some cases, this simply won’t work. Here’s where QR codes come in. I happened upon this blog post which mentioned the idea of using QR codes to store such text as a paper record, able to be machine read for accuracy at a later point. Brilliant!

So here’s a practical example of generating such a paper copy of a password using only online free resources, so no software installation required (of course, there are many programs or apps you may install, should you wish to be off-grid):

The password example:

This1sMy_SuperS3kr3t-pASSwORD=wh1ch*woulD_b3-a-R0y4l+payn3>2>tyP3!

This is a very strong password which, although it isn’t simply random, is still quite secure due to its length (66 chars.) alone. Even the NSA with all its resources would take a very long time to crack it, provided the encryption mechanism doesn’t suffer from a back door or other systemic vulnerability. Given the pseudo english phrasing it would be possible to type or even memorize this password, but it wouldn’t be easy. And a single character discrepancy means not getting in to wherever it protects.

Generating the QR code:
One of many free online QR code generation sites is qrstuff.com. Taking the above password there, we can plug it into their on-line code generator:
Generating the QR code online

And download the image file of that password in a QR code:
Generated QR code

This QR code can then be placed on a printed page.

Reading the QR code to “reawaken” the text:
There are also many online QR reader/decoding sites, including: webqr.com.

This site provides for you to either take a picture of the code via your device’s camera, or upload a file with the code image (say from a scanner or photo of the paper page) and returns the code content.

Uploading the above QR code image file results in the following:
Decoding the QR image

A perfect copy of the original plain text password!

OpenVPN on Tomato with Android and Linux Clients

I’ve been wanting to do this for a very long time. When away from home I sometimes need access to the systems (or data residing on those systems) back at home. I wanted to set up a secure means to access the machines behind my router’s firewall and one of the most versatile and secure ways to do that is with a Virtual Private Network (VPN). The problem was that this stuff is pretty complicated and even though the open source firmware we run on our router has had a VPN-enabled version available, I’ve been loathe to try implementing it.

Well, the garage control system project I was recently working on had a hardware failure such that I could not implement it in the original way intended (until I replace the CAI WebControl board central to it). The board failed in such a way that it would not accept PLC programming but would still respond through the default web interface – which unfortunately is not sufficiently secure to expose to the internet directly. However, we were going away for an extended period and I needed to be able to access it while away. A perfect application for VPN technology, I could keep the “vulnerable” system firewalled behind the router and poke a secure hole through it using the VPN to control it from afar when needed. Just the shove I needed to get going on the VPN!

Curiously enough, in googling, I was able to find various basic tutorials about setting up a Tomato VPN-enabled router (which is Linux based) as a VPN server with Windows clients and creating the certificates and keys on Windows but pretty much nothing simple about doing so with other platforms like mine – Android (again Linux based), Linux and Mac. The ones about setting up a VPN with Linux all seemed to want you doing everything down in the weeds of config files and installing VPN packages on your own server (not a router). Not what I wanted.

The good news for you and me is that I figured out how to get this done with minimal effort and it pretty much worked perfectly on the first try, so I’m writing it up here for future reference and to share with any others following this path. Looking back, it wasn’t that hard but the lack of clear guidance made it all confusing. All that said, here’s some clarity on how to get it done:

Creating Certificates and Keys

On Linux Mint LMDE (Debian Linux) workstation, using Synaptic or another package manager install:
openvpn
easy-rsa

This will install the easy-rsa scripts into
/usr/share/easy-rsa

Taking note of the instructions at http://openvpn.net/index.php/open-source/documentation/howto.html#pki, I did the following:

Copy the easy-rsa files to another location that will persist after package upgrades (note, this location already existed as a result of the openvpn installation and contained the single file update-resolv-conf, so maybe that claim is misleading?) and cd into that directory:
sudo cp -R /usr/share/easy-rsa/* /etc/openvpn/
cd /etc/openvpn

Edited the vars file using vi to set the KEY_COUNTRY, KEY_PROVINCE, KEY_CITY, KEY_ORG, and KEY_EMAIL parameters. These were at the bottom of the file for me. From what I can tell, the two email entries are identical but for the quote symbols. I presume the quoted one is meant to be the “real life name”, but nothing I could easily find via google confirmed or contradicted this – so I just set them both to the same address.

export KEY_COUNTRY="US"
export KEY_PROVINCE="MA"
export KEY_CITY="MyCity"
export KEY_ORG="My ORG Name"
export KEY_EMAIL="vpn_contact@myDomain.com"
export KEY_EMAIL=vpn_contact@myDomain.com

I then completed the rest of the steps at the above link using root/sudo priviledges, creating the certificate authority, server certificate and key and then the client certificates and keys. What I found online was not very informative on this point, but the Commmon Name (CN) must be entered each time you build these items and should be varied so as to be descriptive. So, for each command:

./build-ca
For this I specified my own name as the Common Name (I’m my own certificate authority) and it generated two files, ca.crt and ca.key (note, these are not named after the Common Name given, unlike the following).

./build-key-server ServerName
I gave my intended VPN server name as the ServerName which it then used as the Common Name and generated ServerName.crt, ServerName.csr, ServerName.key plus a 01.pem file and changed the index.txt and serial files in the keys directory.
NOTE: I also here encountered something different than that laid out at the above URL, for each key it asked me for:
Please enter the following 'extra' attributes
to be sent with your certificate request
A challenge password []:
An optional company name []:
which I simply clicked Enter through (I presume to set as blank, as no password was later asked for).

./build-key ClientNameHere
I gave unique descriptive names for each client and it created similar files to the server ones above, named per the client names I gave, created sequentially numbered pem files and updated the index.txt and serial files.

./build-dh
Returned Generating DH parameters, 1024 bit long safe prime, generator 2
This is going to take a long time
(But it didn’t – it was less than 5 seconds on my main Linux 64 bit workstation)

In the Arch Linux wiki entry for EasyRSA it stated that there was a need to convert the server certificate to an encrypted .p12 format for use on Android. I found this to not be needed, using the OpenVPN for Android client from the Google Play Store.

In order to provide additional TLS security and to protect against potential denial of service attacks against my router/VPN server I also set up an HMAC signature:
openvpn --genkey --secret ta.key

Setting the server and clients up…

As I created all the certificates, keys, etc. on my main Debian workstation, I needed to transfer those files to the associated machines. First I used my browser and the Tomato-powered router (VPN server) web interface to set up the VPN server following the info here *except* for using TUN instead of TAP. Installing Tomato is covered in my other blog post. Here’s screenshots of my settings (click on them to enlarge):
Tomato-Version
Tomato-VPN-Basic
Tomato-VPN-Advanced
Tomato-VPN-Keys
Tomato-VPN-Status

Connecting with a Linux machine. I then set up the test client on my Mint LMDE/Debian laptop following the leads at https://support.hidemyass.com/hc/en-us/articles/202721596-OpenVPN-Setup-with-Network-manager-on-Linux-Mint-Mate , which dragged along a bunch of other required packages including openvpn, easy-rsa, etc. I imported the certificates and keys when setting up the VPN connection using NetworkManager. Trying to connect via this initially failed. I thought this might be because I was on my home network at the time, so I proceeded to set up my phone as a client to see if I could use the cellular network to test outside access.

Connecting via Android. I installed OpenVPN for Android from the Google Play store onto my cell phone. Copied over the certs and keys to my phone using USB cable and set up the connection in the app. Took a bit of twiddling to figure out where everything went and which boxes to check, but it connected quickly once set up. Could access private resources behind the router firewall now! I went on to set up my Android tablet with the same app.

Connecting from an Outside Network. Brought my phone, Linux laptop and Android tablet for a drive to find an available Xfinity Wi-Fi connection. Tried each client to access the VPN once connected to some poor folks’ wireless access point (why folks stand for Comcast doing this, I don’t know), and they all connected quickly and could access my Garage Control System web interface on my home network… success!

Note that in none of these set-ups did I need to edit or create any configuration files manually on the clients or server, despite lots of other tutorials making great points of this! It appears each of the OpenVPN server and client implementations I used took care of this for me.

The only bit of weirdness is that I cannot figure how to directly disconnect from the VPN using NetworkManager under MATE desktop on my Linux laptop. I can disconnect the VPN by dropping the wireless connection overall. There should be a “Disconnect VPN” option within NetworkManager but I don’t see it on my laptop when I’m connected (it is there when I’m not!). But that’s a (minor) problem for another day.

I’ve found the disconnect option in the VPN menu under NetworkManager and that can be used to drop the VPN connection. The Android clients have a connection status entry in the notifications list which provides a disconnect option once clicked on. All good to go now!