openvpn on centos

 Make sure to enter a value in Common Name parameter, like “Easiest way to install openvpn
  -- Tried and installed on Centos 64 bit


what is openvpn?
http://en.wikipedia.org/wiki/OpenVPN



Procedure



--- first of all install gcc and make.

#yum install gcc make



Install package needed for OPENVPN
#yum install rpm-build
#yum install autoconf.noarch
#yum install zlib-devel
#yum install pam-devel
#yum install openssl-devel
#yum install lzo-devel
#yum install lzo


Copy the folder for creating certificate to directory /etc/openvpn/
#cp -r /usr/share/doc/openvpn-2.0.9/easy-rsa/ /etc/openvpn/

  Let's create the certificate
#cd /etc/openvpn/easy-rsa/2.0
#chmod 755 *
#source ./vars
#./vars
#./clean-all

Build CA
#./build-ca
 Make sure to enter a value in Common Name parameter, like “ Test server"

 

·         Generate certificate and private key for server.

./build-key-server server

  

     Parameters can be default but when a Common Name is asked, type in “server”.

    

·         Generate certificate and private key for client; client1

./build-key client1

·         Generate Diffie Hellman parameters

./build-dh

Building certificate done, now we create the configuration file in the directory /etc/openvpn
      Sample server,conf file.




 - Restart openvpn -- service openvpn start


Check /var/log/messages if porperly connected the msg. are:

[root@localhost openvpn]# tail -f /var/log/messages
Feb 11 12:01:18 localhost openvpn[9699]: /sbin/ip addr add dev tun0 local 192.168.255.1 peer 192.168.255.2
Feb 11 12:01:18 localhost openvpn[9699]: /sbin/ip route add 192.168.255.0/24 via 192.168.255.2
Feb 11 12:01:18 localhost openvpn[9699]: Data Channel MTU parms [ L:1542 D:1450 EF:42 EB:135 ET:0 EL:0 AF:3/1 ]
Feb 11 12:01:18 localhost openvpn[9708]: Socket Buffers: R=[111616->131072] S=[111616->131072]
Feb 11 12:01:18 localhost openvpn[9708]: UDPv4 link local (bound): [undef]:1194
Feb 11 12:01:18 localhost openvpn[9708]: UDPv4 link remote: [undef]
Feb 11 12:01:18 localhost openvpn[9708]: MULTI: multi_init called, r=256 v=256
Feb 11 12:01:18 localhost openvpn[9708]: IFCONFIG POOL: base=192.168.255.4 size=62
Feb 11 12:01:18 localhost openvpn[9708]: IFCONFIG POOL LIST
Feb 11 12:01:18 localhost openvpn[9708]: Initialization Sequence Completed

--- 10.105

-- Client  Configuration--

-- Copy /etc/openvpn/keys from source to destination server
-  Configure server.conf
-- Restart the service





--If properly configure, the message below should be the same as on your client server

[root@localhost openvpn]# tail -f openvpn-status.log
OpenVPN CLIENT LIST
Updated,Fri Feb 11 12:27:59 2011
Common Name,Real Address,Bytes Received,Bytes Sent,Connected Since
client,192.168.10.105:32777,3798,4019,Fri Feb 11 12:27:38 2011
ROUTING TABLE
Virtual Address,Common Name,Real Address,Last Ref
192.168.255.6,client,192.168.10.105:32777,Fri Feb 11 12:27:38 2011
GLOBAL STATS
Max bcast/mcast queue length,0

Iptables
iptables -t nat -A POSTROUTING -s 10.8.0.0/24 -o eth0 -j MASQUERADE
Creating username/passwd

Install process is done, now create user for you OPENVPN.
#useradd username -s /bin/false
#passwd username

to delete existing user, you can use
#userdel username

Now go to your OPENVPN GUI config folder and create client configuration file. This is the example for client configuration.

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

save the configuration with filename.ovpn.

------

Running OpenVPN client on Windows XP

OpenVPN GUI software is located in http://openvpn.se/download.html

Configuring

You need to create a new configuration file client.ovpn located in C:\Program Files\OpenVPN\config\, for example C:\Program Files\OpenVPN\config\client.ovpn and put these lines into this configuration file:

******************************************
remote remote_vpn_server
tls-client
dev tap
ifconfig local_ip_address netmask
ca ca.crt
cert client.crt
key client.key
ping 10
verb 1
mute 10
comp-lzo
******************************************

Here's explanation of each configuration option:

remote_vpn_server	name of OpenVPN server
local_ip_address	local IP address
netmask	netmask of local IP address
client.crt	client's certificate
client.key	client's key

All this information should be provided by your system administrator.

Place these files client.crt , client.csr, client.key, and ca.crt into directory C:\ProgramFiles\OpenVPN\config

Run OpenVPN GUI from "Start" -> "All programms" -> "OpenVPN" -> "OpenVPN GUI". After you run this software, you should see an icon OpenVPN in system tray. Click on mouse's right button and choose "Connect". After you click on it, it takes about 1 minute to establish connection.