OpenVPN is an open source virtual private network (VPN) software. Follow the steps below to configure OpenVPN on CentOS:
1. Install dependencies:
# yum install gcc make rpm-build autoconf.noarch zlib-devel pam-devel openssl-devel
2. Get OpenVPN:
# wget http://openvpn.net/release/lzo-1.08-4.rf.src.rpm
# wget http://dag.wieers.com/rpm/packages/rpmforge-release/rpmforge-release-0.3.6-1.el5.rf.x86_64.rpm
3. Prepare to install:
# rpmbuild --rebuild lzo-1.08-4.rf.src.rpm
# rpm -Uvh /usr/src/redhat/RPMS/x86_64/lzo-*.rpm
# rpm -Uvh rpmforge-release-0.3.6-1.el5.rf.x86_64.rpm
4. Install OpenVPN:
# yum install openvpn
5. Copy the OpenVPN directory:
# cp -r /usr/share/doc/openvpn-2.2.0/easy-rsa/ /etc/openvpn/
6. Build SSL keys. When prompted for key information, you can simply press enter to bypass:
#cd /etc/openvpn/easy-rsa/2.0
#chmod 755 *
#source ./vars
#./vars
#./clean-all
#./build-ca
#./build-key-server server
#./build-dh
7. Create the OpenVPN config:
# cd /etc/openvpn
# vi server.conf
Copy the following sample config into the document, edit the IP address and port to your main IP address and desired port, then press ESC, then :wq and enter to save and exit the document.
local 123.123.123.123 #- change it with your server ip address
port 1234 #- change the port you want
proto udp #- protocol can be tcp or udp
dev tun
tun-mtu 1500
tun-mtu-extra 32
mssfix 1450
ca /etc/openvpn/easy-rsa/2.0/keys/ca.crt
cert /etc/openvpn/easy-rsa/2.0/keys/server.crt
key /etc/openvpn/easy-rsa/2.0/keys/server.key
dh /etc/openvpn/easy-rsa/2.0/keys/dh1024.pem
plugin /usr/share/openvpn/plugin/lib/openvpn-auth-pam.so /etc/pam.d/login
client-cert-not-required
username-as-common-name
server 10.8.0.0 255.255.255.0
push "redirect-gateway def1"
push "dhcp-option DNS 208.67.222.222"
push "dhcp-option DNS 4.2.2.1"
keepalive 5 30
comp-lzo
persist-key
persist-tun
status server-tcp.log
verb 3
8. Start OpenVPN:
# openvpn /etc/openvpn/server.conf
Check that it returns "Initialization Sequence Completed." If so, press ctrl-c to quit.
9. Setup NAT rules:
# echo 1 > /proc/sys/net/ipv4/ip_forward
# iptables -t nat -A POSTROUTING -s 10.8.0.0/24 -j SNAT --to 0.0.0.0
(Modify "0.0.0.0" to your server's IP)
Create a user to login to the VPN with:
#useradd username -s /bin/false
#passwd username
10. Create an OpenVPN config file on your local machine with name vpn1.ovpn, copy the sample below with your IP and port, and place it in your OpenVPN configurations folder:
client
dev tun
proto udp
remote 123.123.123.123 4567 #- your OPENVPN server ip and port
resolv-retry infinite
nobind
tun-mtu 1500
tun-mtu-extra 32
mssfix 1450
persist-key
persist-tun
ca ca.crt
auth-user-pass
comp-lzo
verb 3
11. Download ca.crt from /etc/openvpn/easy-rsa/2.0/keys to the same OpenVPN configs folder.
12. Start the VPN on the VPS:
# openvpn /etc/openvpn/server.conf
Log in to the VPN from your local machine (using OpenVPN or another desktop client) with the username/password you created.
