Build an OpenVPN server on android device

Preparation

1. An android device, in this case, Sony xperia Z is used
2. Root permission required
3. Linux Deploy for deploy image via chroot/proot
4. OpenVPN

Step

1. Root android device for superuser permission

2. Install Linux Deploy from play store or custom apk.

• Install Linux Deploy

3. Install linux

• Click download icon to select which image to deploy

• Select which distribution and suite to use
• Set user name & password
• Allow init system
• Enable SSH server

• Deploy distribution

• After installation completed, start linux

4. Connect to android via SSH

5. Install OpenVPN

• Install required packages

• Create certification folder and edit vars configuration

• Edit vars as blow

• Build ca, server and client certification

• Copy required certification to the path of openvpn
• Clone configuration file from sample config
• Edit server.conf

• Edit server.conf as blow, modify what your need

• Modify networking config sysctl.conf

• Modify content to allow transfer traffic from vpn

• Make changes work

• Edit firewall rules

• Add following content to allow route from vpn subnet to wireless

• Edit firewall configuration

• Allow forward policy

• Add firewall rule for vpn and ssh
• Make changes work. (In this case, there was some error but I ignore that)

• Start openvpn
• Validate result

6. Use vpn client to connect android device