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OpenVPN server

:!: This page is now obsolete. Users looking to set up OpenVPN should instead visit vpn.openvpn. :!:

OpenVPN server

This guide is based on the use of a stable OpenWrt "Backfire" 10.03.1 OpenVPN. The aim is to show how secure Internet sharing is setup in 7 steps.

As prerequisite make sure you the router has correct date an time (use the "date" command to verify it). OpenVPN needs the router real time clock (RTC)to be accurate. The RTC accurate configuration can be achieved with ntpclient. Check the wiki on how to install and configure ntpclient.


opkg update
opkg install openvpn openvpn-easy-rsa

Configure certificates

cd /etc/easy-rsa
vi vars

*OPTIONAL* (Comment out the following lines if you do not want your certificates to expire)

export CA_EXPIRE=3650
export KEY_EXPIRE=3650

(Change these last lines to suit your own country etc)

export KEY_CITY="SanFrancisco"
export KEY_ORG="Fort-Funston"
export KEY_EMAIL="me@myhost.mydomain"

Generate certificates

  1. OPTIONAL: Clean out the /etc/easy-rsa/keys directory and start fresh.
  2. Build certificates
  3. Create the server key
    build-key-server server
  4. Create client keys. Include a password since many clients may balk at a key without a password.
    Normal Keys:
    build-key client
    Alternatively, create client keys in PKCS12 Format (combines the key and ca certificate in one file)
    build-key-pkcs12 client
  5. Copy the important files to the /etc/openvpn directory, so that they are duplicated
    cd /etc/easy-rsa/keys
    cp dh1024.pem server.crt server.key /etc/openvpn/

Note - if a dh2048.pem file was generated - remember to change 1024 to 2048 on the configuration files below. It's a good idea to make an offline backup of all the generated files in the /etc/easy-rsa/keys directory. Use a utility like WinSCP to transfer the files from the router to your computer. For SFTP support, install the SFTP server on the router:

opkg update
opkg install openssh-sftp-server

That way a SFTP client like Filezilla can be used to transfer files to and from the router.

Create OpenVPN configuration

If you are using UCI to configure your system, use this configuration file:

vi /etc/config/openvpn
config 'openvpn' 'lan'
        option 'enable' '1'
        option 'port' '1194'
        option 'proto' 'udp'
        option 'dev' 'tun'
        option 'ca' '/etc/easy-rsa/keys/ca.crt'
        option 'cert' '/etc/easy-rsa/keys/server.crt'
        option 'key' '/etc/easy-rsa/keys/server.key'
        option 'dh' '/etc/easy-rsa/keys/dh1024.pem'
        option 'ifconfig_pool_persist' '/tmp/ipp.txt'
        option 'keepalive' '10 120'
        option 'comp_lzo' 'no' # this will break the tunnel in chaos calmer
        option 'persist_key' '1'
        option 'persist_tun' '1'
        option 'status' '/var/log/openvpn-status.log' 
        option 'verb' '3'
        option 'server' ''
        option 'client_to_client' '1'
        list 'push' 'redirect-gateway def1'
        list 'push' 'dhcp-option DNS'
	list 'push' 'route'
If you use TunnelBlick to connect, keep in mind that it adds "openvpn" as a search domain which messes up hostnames. By default openwrt adds "lan" as a search domain via the dhcp. so add the following to make sure vpn client will be able to ping machines correctly:
        list 'push' 'dhcp-option DOMAIN lan'

If there are revoked cerficates add also

option 'crl_verify' '/etc/easy-rsa/keys/crl.pem'

This will create a VPN on the 10.0.0.x IP range. If you'd like to choose a different IP range, edit it accordingly. Also change the DNS entry to the IP address of your router if different.

If you are not using UCI configuration, use this configuration file:

vi /etc/openvpn/openvpn.conf

mode server

### network options
port 1194
proto udp
dev tun

### Certificate and key files
ca /etc/easy-rsa/keys/ca.crt
cert /etc/easy-rsa/keys/server.crt
key /etc/easy-rsa/keys/server.key
dh /etc/easy-rsa/keys/dh1024.pem

push "redirect-gateway def1"
push "dhcp-option DNS" # Change this to your router's LAN IP Address
push "route" # Change this to your network

### (optional) compression (Can be slow). If not used specifically set to no and do not comment out.
### with no comp-lzo can result in write to TUN/TAP : Invalid argument (code=22) error
comp-lzo no
#comp-lzo yes


verb 3
keepalive 10 120
log-append /var/log/openvpn/openvpn.log

Configure the firewall

FIXME: A better "more in the principals of UCI" firewall settings can be found at openvpn-streamlined-server-setup the below just bypasses the rules with custom and is not easily visible in LUCI rules.

Why has this FIXME been added? What is wrong/missing, what should be fixed? What is the action that this FIXME should trigger? — tmomas 2015/12/22 20:24

vi /etc/config/firewall

config 'include' option 'path' '/etc/firewall.user' config 'rule' option 'target' 'ACCEPT' option 'name' 'VPN' option 'src' 'wan' option 'proto' 'udp' option 'dest_port' '1194'

vi /etc/firewall.user

iptables -t nat -A prerouting_wan -p udp --dport 1194 -j ACCEPT iptables -A input_wan -p udp --dport 1194 -j ACCEPT iptables -I INPUT -i tun+ -j ACCEPT iptables -I FORWARD -i tun+ -j ACCEPT iptables -I OUTPUT -o tun+ -j ACCEPT iptables -I FORWARD -o tun+ -j ACCEPT

Autostart needed?

- Start openvpn:

/etc/init.d/openvpn start
- Enable openvpn to let it be automatically loaded by init at startup
/etc/init.d/openvpn enable

Configure the client


mkdir ~/VirtualNet

Windows # Create a folder called example VirtualNet in C:/Program Files

Download ca.crt, client.crt, client.key, and dh1024.pem located in /etc/easy-rsa/keys/ on the router, and place them in the VirtualNet dir

# Open up a text editor and add the following lines… # Save the file as client.ovpn in VirtualNet

client tls-client dev tun proto udp remote SERVER-IP 1194 # Change to your router's External IP resolv-retry infinite nobind ca ca.crt cert client.crt key client.key dh dh1024.pem #comp-lzo persist-tun persist-key verb 3

Client Usage GNU/Linux - Download OpenVPN


sudo apt-get install openvpn

Arch Linux

pacman -S openvpn


emerge openvpn

Client Usage Windows - Download OpenVPN client

On Windows XP / 32 Bit *Choose Installation Package*

On Windows Vista 64

Client Usage on Android

  1. Install and run the OpenVPN for Android by Arne Schwabe (
  2. Copy the client.p12 file to your SD card or internal memory.
  3. Create a new profile. Under "Basic" settings, supply your router's WAN IP address or server address and disable "LZO Compression." Choose "PKCS12 File" under "Type" and select client.p12 file. Enter your key's password under "PKCS12 Password" to have it automatically log in.

Note: You may need to install tun.ko using the TUN.ko Installer ( tun.ko may also be compiled into your kernel in which case the tun.ko module is not necessary on your Android device.

Client Usage MacOS X / iOS / ...


Client Usage GNU/Linux Connect

cd /home/your-user/VirtualNet/
sudo openvpn client.ovpn

Client Usage Windows Connect

  • browse to the VirtualNet dir
  • Right click on client.ovpn and choose run with OpenVPN GUI

Known Issue (and Fix) for Windows 10 Client

Windows 10 under-prioritizes OpenVPN Client DNS queries. This causes the Windows OS to use the local network adapter to query DNS instead of the tunneled adapter (TAP-Windows Adapter V9). Ultimately, this prevents DNS queries to occur over the tunneled OpenVPN server network, and leaks DNS queries to your client's local network. OpenVPN Client for windows as of version 2.3.9 provides a fix for this with the use of –block-outside-dns in the server config or client config, see for more info.

inbox/vpn.howto.txt · Last modified: 2016/12/03 03:21 by ExaltedVanguard