I was running Raspbmc in Raspberry Pi which I like to use once a year (but I’m not gonna write about that part). What’s interesting about that device is that I always have it on and it’s connected to my router, so it makes it a great candidate for installing vpn server in it. And instead of getting another Pi to run vpn server and keep it up and running 24/7, it’s a good idea to just install OpenVpn on it also since it’s built on top of linux and that’s what I had. There have been lot of changes to the project and it also changed it’s name to OSMc. So I just decided to reformat, get OSMC and install OpenVpn on it again. Since I didn’t provision that server with chef (would be interesting to see someone run chef client in Pi though) I had to do everything manually again. Decided to write about it in case others would be interested in creating similar setup also. And since OSMC is built on top of Debian, this guide mostly applies to any Debian based setup.

Before anything let’s install needed packages and switch to root user since most of what we’ll do will require sudo permissions:

sudo su
apt-get update && apt-get install -y openvpn easy-rsa

Let’s create easy-rsa folder:

cd /etc/openvpn
mkdir easy-rsa
cp -R /usr/share/easy-rsa/* easy-rsa/

Now set following variables in /etc/openvpn/easy-rsa/vars file:

export KEY_CITY=
export KEY_ORG=
export KEY_EMAIL=
export KEY_OU=

Now let’s kill old keys (if they exist) and source those variables:

cd easy-rsa/
touch keys/index.txt
echo 01 > keys/serial
. ./vars

It’s time to build the keys and certs now. To build CA certificate run:


To build the server key run:

./build-key-server server

To build the DH key run:


To build the TA key run:

openvpn --genkey --secret ta.key

After having keys generated, let’s create the server config in /etc/openvpn/server.conf file:

port 1194
proto udp
dev tun

ca      /etc/openvpn/easy-rsa/keys/ca.crt    # generated keys
cert    /etc/openvpn/easy-rsa/keys/server.crt
key     /etc/openvpn/easy-rsa/keys/server.key  # keep secret
dh      /etc/openvpn/easy-rsa/keys/dh2048.pem

tls-auth /etc/openvpn/easy-rsa/keys/ta.key 0

server  # internal tun0 connection IP
ifconfig-pool-persist ipp.txt

keepalive 10 120

comp-lzo         # Compression - must be turned on at both end

# To forward traffic
push "redirect-gateway def1 bypass-dhcp"
# For hostnames to resolve
push "dhcp-option DNS"

status /var/log/openvpn-status.log

verb 3  # verbose mode

Here open vpn will listen on 1194 and it’s udp, if you want it to listen on a different port or be tcp, make sure to change this. redirect-gateway is to forward internet traffic and to be able to access other boxes on the network. Next line is to resolve dns. I put my router gateway so local hostnames will also resolve. Your gateway may be different. If for a scpecific client we don’t want to redirect internet traffic we can add this to client config:

dhcp-option DNS

Now we need to configure os for forwarding. Run:

echo 1 > /proc/sys/net/ipv4/ip_forward

Open */etc/sysctl.conf file and uncomment net.ipv4.ip_forward = 1 line.

This will allow port forwarding but we still need to configure the firewall.

iptables -A FORWARD -i wlan0 -o tun0 -m state --state ESTABLISHED,RELATED -j ACCEPT
iptables -A FORWARD -s -o wlan0 -j ACCEPT
iptables -t nat -A POSTROUTING -s -o wlan0 -j MASQUERADE
iptables-save > /etc/iptables.up.rules

This will configure firewall for forwarding and we save the configuration to /etc/iptables.up.rules file. We need to restore those settings when interface starts after the reboot. Let’s create a script file for it /etc/network/if-pre-up.d/iptables:

/sbin/iptables-restore < /etc/iptables.up.rules

And make the script executable:

chmod +x /etc/network/if-pre-up.d/iptables

Now vpn server is configured. We need to restart OpenVpn or just reboot the server to make sure that firewall will still work.

Client setup

For mac I like to use Tunnelblick client and for iOS OpenVpn app. This should be almost same setup even if you prefer to use other clients.

Again, let’s switch to root user, source the variables and generate client certs.

sudo su
cd /etc/openvpn/easy-rsa
. ./vars
./build-key-pass CLIENT NAME

I like to generate one key per device I’m using and I prefer to have password for my mac client (using build-key-pass) and no password for iOS client (using build-key).

We need to create the client config file also, which should look something like this:

dev tun
port 1194
proto udp

remote SERVER DNS 1194

ca ca.crt
cert CLIENT NAME.crt
tls-auth ta.key 1


verb 3

Make sure to set SERVER DNS and CLIENT NAME. For Tunnelblick we can just create a folder which name ends with .tblk, put config file, ca.crt, and our client .crt and .key files in it. Securely transfer this folder to client and open it while you have Tunnelblick installed. Tunnelblick will create a configuration for it.

For iOS, setup is similar but we’ll use .ovpn file with certs and key embedded in it. Save the above config in .ovpn file without ca, cert and key lines, name it your CLIENT NAME.ovpn and run following lines:

echo "<tls-auth>" >>  CLIENT NAME.ovpn
cat ta.key | grep -A 100 "BEGIN OpenVPN Static key V1" | grep -B 100 "END OpenVPN Static key V1" >>  CLIENT NAME.ovpn
echo "</tls-auth>" >>  CLIENT NAME.ovpn

echo "set CLIENT_CERT 0" >> CLIENT NAME.ovpn
echo "<ca>" >> CLIENT NAME.ovpn
cat ca.crt | grep -A 100 "BEGIN CERTIFICATE" | grep -B 100 "END CERTIFICATE" >> CLIENT NAME.ovpn
echo "</ca>" >> CLIENT NAME.ovpn

echo "<cert>" >> CLIENT NAME.ovpn
cat CLIENT NAME.crt | grep -A 100 "BEGIN CERTIFICATE" | grep -B 100 "END CERTIFICATE" >> CLIENT NAME.ovpn
echo "</cert>" >> CLIENT NAME.ovpn

echo "<key>" >> CLIENT NAME.ovpn
cat CLIENT NAME.key | grep -A 100 "BEGIN PRIVATE KEY" | grep -B 100 "END PRIVATE KEY" >> CLIENT NAME.ovpn
echo "</key>" >> CLIENT NAME.ovpn

Note to change CLIENT NAME to your client name. Transfer this file securely to your phone and open it while you have OpenVpn installed.