OpenVPN server on Amazon EC2
I was recently asked to set up a personal VPN for a friend here in Beijing and thought I’d share my process. I went with Amazon’s EC2 service because they have a reasonable choice of DC locations and their “micro” instances are free to trial for one year.
I’m assuming that you already have an AWS account, if not then create one and login to the EC2 console to follow along.
Provision the EC2 instance
Launch a new “micro” instance using the latest Amazon Linux AMI image. Don’t forget to save the PEM keyfile.
Create & assign a new Security Group (I called mine “openvpn” but name isn’t important) and open the following ports: 22 (TCP) and 1194 (TCP & UDP).
Login via SSH using the PEM file you downloaded and run the initial updates:
$ ssh ec2-user@[ec2-hostname] -i path/to/keyfile.pem
$ sudo yum upgrade
Enable the EPEL repository which contains the openvpn package. EPEL is
installed by default but not enabled, so edit
and change the
enabled=0 line to
enabled=1. It should look like this:
[epel] name=Extra Packages for Enterprise Linux 6 - $basearch #baseurl=http://download.fedoraproject.org/pub/epel/6/$basearch mirrorlist=https://mirrors.fedoraproject.org/metalink?repo=epel-6&arch=$basearch failovermethod=priority enabled=1 #includepkgs=pkg1,pkg2,pkg3 includepkgs=fcgi-devel,fcgi,spawn-fcgi gpgcheck=1 gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-EPEL-6
Then install as normal via yum:
$ sudo yum install openvpn
Configuring the OpenVPN server
Please note: at this point you can follow any of the usual openvpn guides found online. I opted for a TUN configuration using a pre-shared key for simplicity. This works fine for the purpose of tunneling all network traffic to circumvent the GFW here. Your needs may vary, so please read the openvpn manpage and the online docs.
Firstly we need to generate the pre-shared key. This isn’t user-specific so I put it in the system config directory:
$ sudo openvpn —genkey —secret /etc/openvpn/key.txt
Also in the config directory is the
openvpn.conf file which should look like
dev tun port 1194 proto udp secret key.txt ifconfig 192.168.2.1 192.168.2.2 keepalive 10 120 comp-lzo persist-key persist-tun status server.log
You’ll also need to enable IP forwarding in the openvpn initialisation file in
/etc/init.d/openvpn. Open the file in an editor and search for “ip_forward”.
Uncomment the line, save and exit. It should look like this:
echo 1 > /proc/sys/net/ipv4/ip_forward
Finally, start the server process:
$ sudo service openvpn start
Configure the firewall for forwarding/masquerading
The openvpn server can’t do much except accept packets unless you configure
iptables appropriately. Edit
/etc/sysconfig/iptables with the following:
*nat :POSTROUTING ACCEPT [0:0] :PREROUTING ACCEPT [0:0] :OUTPUT ACCEPT [0:0] -A POSTROUTING -s 192.168.2.0/24 -d 0.0.0.0/0 -o eth0 -j MASQUERADE COMMIT
Restart iptables to load the new config:
$ sudo service iptables restart
Lastly, set both openvpn and iptables to start on boot:
$ sudo chkconfig openvpn on && sudo chkconfig iptables on
OpenVPN client config
All clients will need a copy of the
/etc/openvpn/key.txt file and the
following config file:
dev tun proto udp remote [your ec2 hostname goes here] 1194 resolv-retry infinite nobind secret key.txt ifconfig 192.168.2.2 192.168.2.1 comp-lzo dhcp-option DNS 172.16.0.23 redirect-gateway def1
I tested this using the Windows OpenVPN client from openvpn.se, but it
should work fine with any client so long as you put