Step-by-step guide to setting up an OpenVPN server on Amazon AWS EC2 T4g using Ubuntu 22.04 arm64.
Since you're looking for instructions on how to build your own OpenVPN server, I'll assume you have an Amazon AWS account and some experience with it, so I can skip the part about creating an EC2 instance.
Step 1: ssh into the EC2 instance you set up just now
$ ssh -i ovpn.pem [email protected]
Step 2: Install openvpn and easy-rsa
$ sudo apt install openvpn easy-rsa
Step 3: Set Certificate Authority (CA) and generate certificates and keys for an OpenVPN server and clients
$ mkdir ~/easy-rsa $ ln -s /usr/share/easy-rsa/* ~/easy-rsa/ $ cd ~/easy-rsa $ ./easyrsa init-pki $ ./easyrsa build-ca $ ./easyrsa build-server-full server ### for openvpn server $ ./easyrsa build-client-full client ### for openvpn client $ ./easyrsa gen-dh
Note: You will be asked to set one passphrase for each certificate and key. Choose one you like and you will need it later.
Step 4: Have certificates and keys in place for OpenVPN server
$ cd /etc/openvpn/ $ sudo mkdir keys $ cd keys $ sudo cp ~/easy-rsa/pki/ca.crt . $ sudo cp ~/easy-rsa/pki/issued/server.crt . $ sudo cp ~/easy-rsa/pki/dh.pem . $ sudo cp ~/easy-rsa/pki/private/server.key .
Step 5: Have an OpenVPN server config ovpn.conf ready under /etc/openvpn/. Following is mine as an example.
# Which TCP/UDP port should OpenVPN listen on? # If you want to run multiple OpenVPN instances # on the same machine, use a different port # number for each one. You will need to # open up this port on your firewall. port 1194 # TCP or UDP server? proto udp # "dev tun" will create a routed IP tunnel, # "dev tap" will create an ethernet tunnel. # Use "dev tap0" if you are ethernet bridging # and have precreated a tap0 virtual interface # and bridged it with your ethernet interface. # If you want to control access policies # over the VPN, you must create firewall # rules for the the TUN/TAP interface. # On non-Windows systems, you can give # an explicit unit number, such as tun0. # On Windows, use "dev-node" for this. # On most systems, the VPN will not function # unless you partially or fully disable # the firewall for the TUN/TAP interface. dev tun # SSL/TLS root certificate (ca), certificate # (cert), and private key (key). Each client # and the server must have their own cert and # key file. The server and all clients will # use the same ca file. # # See the "easy-rsa" directory for a series # of scripts for generating RSA certificates # and private keys. Remember to use # a unique Common Name for the server # and each of the client certificates. # # Any X509 key management system can be used. # OpenVPN can also use a PKCS #12 formatted key file # (see "pkcs12" directive in man page). ca keys/ca.crt cert keys/server.crt key keys/server.key # This file should be kept secret # Diffie hellman parameters. # Generate your own with: # openssl dhparam -out dh1024.pem 1024 # Substitute 2048 for 1024 if you are using # 2048 bit keys. dh keys/dh.pem # Configure server mode and supply a VPN subnet # for OpenVPN to draw client addresses from. # The server will take 10.8.0.1 for itself, # the rest will be made available to clients. # Each client will be able to reach the server # on 10.8.0.1. Comment this line out if you are # ethernet bridging. See the man page for more info. server 10.8.0.0 255.255.255.0 # If enabled, this directive will configure # all clients to redirect their default # network gateway through the VPN, causing # all IP traffic such as web browsing and # and DNS lookups to go through the VPN # (The OpenVPN server machine may need to NAT # the TUN/TAP interface to the internet in # order for this to work properly). # CAVEAT: May break client's network config if # client's local DHCP server packets get routed # through the tunnel. Solution: make sure # client's local DHCP server is reachable via # a more specific route than the default route # of 0.0.0.0/0.0.0.0. push "redirect-gateway def1 bypass-dhcp" # Pushing DNS to clients push "dhcp-option DNS 1.1.1.1" #Cloudflare push "dhcp-option DNS 1.0.0.1" #Cloudflare # The keepalive directive causes ping-like # messages to be sent back and forth over # the link so that each side knows when # the other side has gone down. # Ping every 10 seconds, assume that remote # peer is down if no ping received during # a 120 second time period. keepalive 10 120 # Select a cryptographic cipher. # This config item must be copied to # the client config file as well. # Note that v2.4 client/server will automatically # negotiate AES-256-GCM in TLS mode. # See also the ncp-cipher option in the manpage #cipher AES-256-CBC # Enable compression on the VPN link and push the # option to the client (v2.4+ only, for earlier # versions see below) ;compress lz4-v2 ;push "compress lz4-v2" # For compression compatible with older clients use comp-lzo # If you enable it here, you must also # enable it in the client config file. ;comp-lzo # Notify the client that when the server restarts so it # can automatically reconnect. explicit-exit-notify 1 # The maximum number of concurrently connected # clients we want to allow. max-clients 10 # The persist options will try to avoid # accessing certain resources on restart # that may no longer be accessible because # of the privilege downgrade. persist-key persist-tun # Output a short status file showing # current connections, truncated # and rewritten every minute. status /var/log/openvpn-status.log # By default, log messages will go to the syslog (or # on Windows, if running as a service, they will go to # the "\Program Files\OpenVPN\log" directory). # Use log or log-append to override this default. # "log" will truncate the log file on OpenVPN startup, # while "log-append" will append to it. Use one # or the other (but not both). log-append /var/log/openvpn.log # Set the appropriate level of log # file verbosity. # # 0 is silent, except for fatal errors # 4 is reasonable for general usage # 5 and 6 can help to debug connection problems # 9 is extremely verbose verb 3 # Silence repeating messages. At most 20 # sequential messages of the same message # category will be output to the log. ;mute 20 # Misc askpass pass.txt # It's a good idea to reduce the OpenVPN # daemon's privileges after initialization. # # You can uncomment this out on # non-Windows systems. ;user nobody ;group nobody # CRL-VERIFY - for revoking users ;crl-verify keys/crl.pem
Step 6: Have a text file named pass.txt under /etc/openvpn/, and have the passphrase you chose earlier on it. And then set the permission to 400 for security.
$ sudo echo {your passphrase} > /etc/openvpn/pass.txt
$ sudo chmod 400 /etc/openvpn/pass.txt
Step 7: Firewall & Routing Configurations
$ (ip -4 route ls | grep default | grep -Po '(?<=dev )(\S+)' | head -1)
My output is ens5, which is the public network interface of my EC2.
sudo vim /etc/ufw/before.rules
Adding the following lines before # Don't delete these required lines, otherwise there will be errors
# START OPENVPN RULES # NAT table rules *nat :POSTROUTING ACCEPT [0:0] # Allow traffic from OpenVPN client to ens5. Change ens5 to your interface here. Mine is ens5. -A POSTROUTING -s 10.8.0.0/8 -o ens5 -j MASQUERADE COMMIT # END OPENVPN RULES
$ sudo vim /etc/default/ufw
Change the value of DEFAULT_FORWARD_POLICY from DROP to ACCEPT.
DEFAULT_FORWARD_POLICY="ACCEPT"
$ sudo ufw disable;sudo ufw enable
Step 8: Congratulations! It’s time to launch your first OpenVPN server on Amazon EC2!
$ sudo service openvpn start
Step 1: Navigate to ~/easy-rsa
$ cd ~/easy-rsa
Step 2: Revoke the access (Let's assume I want to revoke the access of a client that I previously granted
$ ./easyrsa revoke client
Type 'yes' manually when you see the following message: Type the word 'yes' to continue, or any other input to abort. Continue with revocation:
Enter passphrase you set for your ca.key
Step 3: Run gen-crl
$ ./easyrsa gen-crl
Step 4: Upload a CRL (if you have done it before you can skip the step)
$ cd /etc/openvpn/keys/
$ sudo ln -s ~/easy-rsa/pki/crl.pem crl.pem
Step 5: Update your ovpn.conf and uncomment ;crl-verify keys/crl.pem (if you have done it before you can skip the step)
;crl-verify keys/crl.pem ==> crl-verify keys/crl.pem
Step 6: Restart OpenVPN server
sudo service openvpn restart
Step 7: Now the ios device has lost the access to the VPN service!