OpenVPN on Centos 6
Tested on Centos 6.7 and OpenVPN 2.3.10
Install Epel repository
yum install epel-release
Install dependencies and the OpenVPN
yum install wget nano unzip openvpn cd /etc/openvpn/ wget https://github.com/OpenVPN/easy-rsa/archive/master.zip unzip master.zip cp -R easy-rsa-master/easyrsa3 server cd server ./easyrsa init-pki ./easyrsa build-ca ./easyrsa gen-req server nopass ./easyrsa sign-req server server ./easyrsa gen-dh cp /etc/openvpn/server/pki/ca.crt /etc/openvpn/ cp /etc/openvpn/server/pki/issued/server.crt /etc/openvpn/ cp /etc/openvpn/server/pki/dh.pem /etc/openvpn/ cp /etc/openvpn/server/pki/private/server.key /etc/openvpn/
Generate client
cp -R /etc/openvpn/easy-rsa-master/easyrsa3 /etc/openvpn/client1 cd /etc/openvpn/client1/ ./easyrsa init-pki ./easyrsa gen-req client1 nopass cd /etc/openvpn/server ./easyrsa import-req /etc/openvpn/client1/pki/reqs/client1.req client1 ./easyrsa sign-req client client1
Enable forwarding
nano /etc/sysctl.conf
Set the following value:
net.ipv4.ip_forward = 1
Save the file and apply the changes:
sysctl -p
Add firewall rules. Note: change venet0 to your actual interface.
iptables -A FORWARD -i tun+ -o venet0 -j ACCEPT iptables -t nat -A POSTROUTING -s 10.8.0.0/24 -o venet0 -j MASQUERADE iptables-save >/etc/sysconfig/iptables service iptables restart
Create openvpn conf file
nano /etc/openvpn/server.conf
port 1194 proto udp dev tun ca ca.crt cert server.crt key server.key # This file should be kept secret dh dh.pem server 10.8.0.0 255.255.255.0 push "redirect-gateway def1" ifconfig-pool-persist ipp.txt keepalive 10 120 comp-lzo persist-key persist-tun status openvpn-status.log verb 3
Start OpenVPN daemon:
service openvpn start chkconfig openvpn on chkconfig iptables on
The files you will need on a client side:
/etc/openvpn/client1/pki/private/client1.key /etc/openvpn/server/pki/issued/client1.crt /etc/openvpn/server/pki/ca.crt
How to configure OpenVPN client on Windows
Also refer to this guide if you would like to install double vpn
You may try to set constant buffer values inb order to increase openvpn tunnel speed if you have client on Windows and Linux openvpn server., just add the next lines to the server.conf:
sndbuf 393216 #server value rcvbuf 393216 # push "sndbuf 393216" #client pushed value for any case to force and override any other params push "rcvbuf 393216" #
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