Open VPN Installation on Centos 6.5

In a rush , so will jot down the steps only. You’ll need epel repo

On CentOS 6 , that will be

wget http://dl.fedoraproject.org/pub/epel/6/x86_64/epel-release-6-8.noarch.rpm
sudo rpm -Uvh epel-release-6*.rpm

Once that is done ,

1. yum install openvpn easy-rsa
2. mkdir -p /etc/openvpn/easy-rsa/keys
3. cp -rf /usr/share/easy-rsa/2.0/* /etc/openvpn/easy-rsa/
4. vi /etc/openvpn/easy-rsa/vars

Modify these parameters to suit your need

[...]
# Don't leave any of these fields blank.
export KEY_COUNTRY="PK"
export KEY_PROVINCE="Punjab"
export KEY_CITY="Multan"
export KEY_ORG="LinuxPakistan"
export KEY_EMAIL="vpn@linux.net.pk"
export KEY_OU="server"
[...]

5. cd /etc/openvpn/easy-rsa/
6. cp openssl-1.0.0.cnf openssl.cnf
7. source ./vars
8. ./clean-all
9. ./build-ca

Generating a 2048 bit RSA private key
......................................................+++
............................................................+++
writing new private key to 'ca.key'
-----
You are about to be asked to enter information that will be incorporated
into your certificate request.
What you are about to enter is what is called a Distinguished Name or a DN.
There are quite a few fields but you can leave some blank
For some fields there will be a default value,
If you enter '.', the field will be left blank.
-----
Country Name (2 letter code) [PK]: ----> Press Enter
State or Province Name (full name) [Punjab]: ----> Press Enter
Locality Name (eg, city) [Multan]: ----> Press Enter
Organization Name (eg, company) [LinuxPakistan]: ----> Press Enter
Organizational Unit Name (eg, section) [server]: ----> Press Enter
Common Name (eg, your name or your server's hostname) [server]: ----> Press Enter
Name [EasyRSA]: ----> Press Enter
Email Address [vpn@linux.net.pk]: ----> Press Enter

10. ./build-key-server server
11. ./build-key client ( if you want to use RSA Keys for Connectivity )

12. ./build-dh
13. cd /etc/openvpn/easy-rsa/keys/
14. cp dh2048.pem ca.crt server.crt server.key /etc/openvpn/
15. vi /etc/openvpn/server.conf

Use my configuration file from this post

And that should do it

IP Routing

vi /etc/sysctl.conf

Set the value of the parameter

below to 1 to allow IP Packet Forwarding from VPN clients

# Controls IP packet forwarding
net.ipv4.ip_forward = 1

Reload sysctl

sysctl -p

Finally some iptables magic to do the masquerading

iptables -t nat -A POSTROUTING -s 10.8.0.0/24 -o eth0 -j MASQUERADE

Save and Restart the Firewall

service iptables save
service iptables restart