OpenVPN: Simple Server using Script

sumber: https://www.cyberciti.biz/faq/howto-setup-openvpn-server-on-ubuntu-linux-14-04-or-16-04-lts/

I am a new Ubuntu Linux server user. How do I setup an OpenVPN Server on Ubuntu Linux version 14.04 or 16.04/18.04 LTS server to shield my browsing activity from bad guys on public Wi-Fi, and more?

OpenVPN is a full-featured SSL VPN (virtual private network). It implements OSI layer 2 or 3 secure network extension using the SSL/TLS protocol. It is an open source software and distributed under the GNU GPL. A VPN allows you to connect securely to an insecure public network such as wifi network at the airport or hotel. VPN is also required to access your corporate or enterprise or home server resources. You can bypass geo-blocked site and increase your privacy or safety online. This tutorial provides step-by-step instructions for configuring an OpenVPN “road warrior” server on Ubuntu Linux v14.04/16.04 LTS version including ufw/iptables firewall configuration. The steps are as follows:

   Find and note down your public IP address
   Download openvpn-install.sh script
   Run openvpn-install.sh to install OpenVPN server
   Connect an OpenVPN server using IOS/Android/Linux/Windows client
   Verify your connectivity

Find your public IP address

Use any one of the following command to find out your IPv4 public address. If your internface name is eth0 or eth1, enter:

$ ip addr show eth0

OR

$ ip addr show eth1

Or use the host command or dig command as follows:

$ host myip.opendns.com resolver1.opendns.com

OR

$ dig TXT +short o-o.myaddr.l.google.com @ns1.google.com

Sample outputs:

Fig.01: Find out your public IPv4 address using the CLI
Fig.01: Find out your public IPv4 address using the CLI

Note down the public IP address 139.59.1.155 i.e. public ip address of your OpenVPN server.

Download openvpn-install.sh script to set up OpenVPN server in 5 minutes on Ubuntu

Type the following wget command or curl command:

$ wget https://git.io/vpn -O openvpn-install.sh
openvpn-install.sh

Run openvpn-install.sh to install OpenVPN server

$ sudo bash openvpn-install.sh

That is all. Your OpenVPN server has been configured and ready to use. You can see added firewall rules /etc/rc.local file:

$ cat /etc/rc.local

Sample outputs:

iptables -I FORWARD -m state --state RELATED,ESTABLISHED -j ACCEPT
iptables -I FORWARD -s 10.8.0.0/24 -j ACCEPT
iptables -I INPUT -p udp --dport 1194 -j ACCEPT
iptables -t nat -A POSTROUTING -s 10.8.0.0/24 -j SNAT --to 139.59.1.155

You can view your openvpn server config file generated by the script as follows (do not edit this file by hand):

$ sudo more /etc/openvpn/server.conf
$ sudo vi /etc/openvpn/server.conf

Sample outputs:

port 1194
proto udp
dev tun
sndbuf 0
rcvbuf 0
ca ca.crt
cert server.crt
key server.key
dh dh.pem
tls-auth ta.key 0
topology subnet
server 10.8.0.0 255.255.255.0
ifconfig-pool-persist ipp.txt
push "redirect-gateway def1 bypass-dhcp"
push "dhcp-option DNS 8.8.8.8"
push "dhcp-option DNS 8.8.4.4"
keepalive 10 120
cipher AES-128-CBC
comp-lzo
user nobody
group nogroup
persist-key
persist-tun
status openvpn-status.log
verb 3
crl-verify crl.pem

How do I start/stop/restart OpenVPN server on Ubuntu Linux 16.04/18.04 LTS?

Type the following command stop the OpenVPN service:

$ sudo systemctl stop openvpn@server

Type the following command start the OpenVPN service:

$ sudo systemctl start openvpn@server

Type the following command restart the OpenVPN service:

$ sudo systemctl restart openvpn@server

How do I start/stop/restart OpenVPN server on Ubuntu Linux 14.04 LTS?

Type the following command stop the OpenVPN service:

$ sudo /etc/init.d/openvpn stop

Type the following command start the OpenVPN service:

$ sudo /etc/init.d/openvpn start

Type the following command restart the OpenVPN service:

$ sudo /etc/init.d/openvpn restart

{Optional} How to configure and use the ufw firewall rules for the OpenVPN server

The default rules added to the /etc/rc.local file should work out of the box. However, if you have complicated firewall settings or prefer ufw to control all firewall settings on Ubuntu Linux server, try the following. First, edit the /etc/rc.local file using a text editor and comment out all firewall rules added by the script. Type the following ufw command to open port 1194 and 22 (ssh):

$ sudo ufw allow 1194/udp
$ sudo ufw allow 22/tcp

Edit the file /etc/ufw/before.rules, enter:

$ sudo vi /etc/ufw/before.rules

Save and close the file. Next edit the /etc/ufw/sysctl.conf file, enter:

$ sudo vi /etc/ufw/sysctl.conf

Find and uncomment the following line to allow this host to route packets between interfaces

net/ipv4/ip_forward=1

Save and close the file. Enable ufw or reload if already running:

$ sudo ufw enable

OR

$ sudo ufw reload

Verify new firewall rules:

$ sudo ufw status
$ sudo iptables -t nat -L -n -v
$ sudo iptables -L FORWARD -n -v
$ sudo iptables -L ufw-before-forward -n -v

Client configuration

On server your will find a client configuration file called ~/iphone.ovpn. All you have to do is copy this file to your local desktop using the scp and provide this file to your OpenVPN client to connect:

$ scp vivek@139.59.1.155:~/iphone.ovpn .

Next, you need to download OpenVPN client as per your operating system:

   Download OpenVPN client for Apple IOS version 6.x or above and install it.
   Download OpenVPN client for Android and install it.
   Download OpenVPN client for Apple MacOS (OS X) and install it.
   Download OpenVPN client for Windows 8/10 and install it.

MacOS/OS X OpenVPN client configuration

Just double click on iphone.ovpn file and it will open in your tunnelblick client > Click on the “Only me” to install it. Fig.03: MacOS / OS X openvpn client configuration Fig.03: MacOS / OS X openvpn client configuration

Once installed click on Connect button and you will be online. Use the following command on MacOS client to verify that your public IP changed to the VPN server IP: $ dig TXT +short o-o.myaddr.l.google.com @ns1.google.com

You can ping to OpenVPN server private IP:

$ ping 10.8.0.1

Linux OpenVPN client configuration

First, install the openvpn client, enter:

$ sudo yum install openvpn

OR

$ sudo apt install openvpn

Next, copy iphone.ovpn as follows:

$ sudo cp iphone.ovpn /etc/openvpn/client.conf

Test connectivity from the CLI:

$ sudo openvpn --client --config /etc/openvpn/client.conf

Your Linux system will automatically connect when computer restart using /etc/init.d/openvpn script:

$ sudo /etc/init.d/openvpn start

For systemd based system, use the following command:

$ sudo systemctl start openvpn@client

Test the connectivity:

$ ping 10.8.0.1 #Ping to OpenVPN server gateway
$ ip route #Make sure routing setup
$ dig TXT +short o-o.myaddr.l.google.com @ns1.google.com #Make sure your public IP set to OpenVPN server

FreeBSD OpenVPN client configuration

First, install the openvpn client, enter:

$ sudo pkg install openvpn

Next, copy iphone.ovpn as follows:

$ mkdir -p /usr/local/etc/openvpn/
$ sudo cp iphone.ovpn /usr/local/etc/openvpn/client.conf

Edit /etc/rc.conf and add the following:

openvpn_enable="YES"
openvpn_configfile="/usr/local/etc/openvpn/client.conf"

Start the OpenVPN service:

$ sudo /usr/local/etc/rc.d/openvpn start

Verify it:

$ ping 10.8.0.1 #Ping to OpenVPN server gateway
$
$ netstat -nr #Make sure routing setup
$
$ drill myip.opendns.com @resolver1.opendns.com #Make sure your public IP set to OpenVPN server

How do I add a new client?

For demo purpose I added a new device called iphone. Let us add one more device called googlephone by running the script again:

$ sudo bash openvpn-install.sh

Sample outputs:

Looks like OpenVPN is already installed

What do you want to do?

  1) Add a cert for a new user
  2) Revoke existing user cert
  3) Remove OpenVPN
  4) Exit

Select an option [1-4]:

Referensi

• https://www.cyberciti.biz/faq/howto-setup-openvpn-server-on-ubuntu-linux-14-04-or-16-04-lts/

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