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Raspberry Pi VPN Router

Raspberry Pi VPN Router

This is a quick-and-dirty guide to setting up a Raspberry Pi as a "router on a stick" to PrivateInternetAccess VPN.

Requirements

Install Raspbian Jessie (2016-05-27-raspbian-jessie.img) to your Pi's sdcard.

Use the Raspberry Pi Configuration tool or sudo raspi-config to:

  • Expand the root filesystem and reboot
  • Boot to commandline, not to GUI
  • Configure the right keyboard map and timezone
  • Configure the Memory Split to give 16Mb (the minimum) to the GPU
  • Consider overclocking to the Medium (900MHz) setting on Pi 1, or High (1000MHz) setting on Pi 2

IP Addressing

My home network is setup as follows:

  • Internet Router: 192.168.1.1
  • Subnet Mask: 255.255.255.0
  • Router gives out DHCP range: 192.168.100-200

If your network range is different, that's fine, use your network range instead of mine.

I'm going to give my Raspberry Pi a static IP address of 192.168.1.2 by configuring /etc/network/interfaces like so:

auto lo
iface lo inet loopback

auto eth0
allow-hotplug eth0
iface eth0 inet static
    address 192.168.1.2
    netmask 255.255.255.0
    gateway 192.168.1.1
    dns-nameservers 8.8.8.8 8.8.4.4

You can use WiFi if you like, there are plenty tutorials around the internet for setting that up, but this should do:

auto lo
iface lo inet loopback

auto eth0
allow-hotplug eth0
iface eth0 inet manual

auto wlan0
allow-hotplug wlan0
iface wlan0 inet static
    wpa-ssid "Your SSID"
    wpa-psk  "Your Password"
    address 192.168.1.2
    netmask 255.255.255.0
    gateway 192.168.1.1
    dns-nameservers 8.8.8.8 8.8.4.4

You only need one connection into your local network, don't connect both Ethernet and WiFi. I recommend Ethernet if possible.

NTP

Accurate time is important for the VPN encryption to work. If the VPN client's clock is too far off, the VPN server will reject the client.

You shouldn't have to do anything to set this up, the ntp service is installed and enabled by default.

Double-check your Pi is getting the correct time from internet time servers with ntpq -p, you should see at least one peer with a + or a * or an o, for example:

$ ntpq -p
     remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
-0.time.xxxx.com 104.21.137.30    2 u   47   64    3  240.416    0.366   0.239
+node01.jp.xxxxx 226.252.532.9    2 u   39   64    7  241.030   -3.071   0.852
*t.time.xxxx.net 104.1.306.769    2 u   38   64    7  127.126   -2.728   0.514
+node02.jp.xxxxx 250.9.592.830    2 u    8   64   17  241.212   -4.784   1.398

Setup VPN Client

Install the OpenVPN client:

sudo apt-get install openvpn

Download and uncompress the PIA OpenVPN profiles:

wget https://www.privateinternetaccess.com/openvpn/openvpn.zip
sudo apt-get install unzip
unzip openvpn.zip -d openvpn

Copy the PIA OpenVPN certificates and profile to the OpenVPN client:

sudo cp openvpn/ca.rsa.2048.crt openvpn/crl.rsa.2048.pem /etc/openvpn/
sudo cp openvpn/Japan.ovpn /etc/openvpn/Japan.conf

You can use a diffrent VPN endpoint if you like. Note the extension change from ovpn to conf.

Create /etc/openvpn/login containing only your username and password, one per line, for example:

user12345678
MyGreatPassword

Change the permissions on this file so only the root user can read it:

sudo chmod 600 /etc/openvpn/login

Setup OpenVPN to use your stored username and password by editing the the config file for the VPN endpoint:

sudo nano /etc/openvpn/Japan.conf

Change the following lines so they go from this:

ca ca.rsa.2048.crt
auth-user-pass
crl-verify crl.rsa.2048.pem

To this:

ca /etc/openvpn/ca.rsa.2048.crt
auth-user-pass /etc/openvpn/login
crl-verify /etc/openvpn/crl.rsa.2048.pem

Test VPN

At this point you should be able to test the VPN actually works:

sudo openvpn --config /etc/openvpn/Japan.conf

If all is well, you'll see something like:

$ sudo openvpn --config /etc/openvpn/Japan.conf 
Sat Oct 24 12:10:54 2015 OpenVPN 2.3.4 arm-unknown-linux-gnueabihf [SSL (OpenSSL)] [LZO] [EPOLL] [PKCS11] [MH] [IPv6] built on Dec  5 2014
Sat Oct 24 12:10:54 2015 library versions: OpenSSL 1.0.1k 8 Jan 2015, LZO 2.08
Sat Oct 24 12:10:54 2015 UDPv4 link local: [undef]
Sat Oct 24 12:10:54 2015 UDPv4 link remote: [AF_INET]123.123.123.123:1194
Sat Oct 24 12:10:54 2015 WARNING: this configuration may cache passwords in memory -- use the auth-nocache option to prevent this
Sat Oct 24 12:10:56 2015 [Private Internet Access] Peer Connection Initiated with [AF_INET]123.123.123.123:1194
Sat Oct 24 12:10:58 2015 TUN/TAP device tun0 opened
Sat Oct 24 12:10:58 2015 do_ifconfig, tt->ipv6=0, tt->did_ifconfig_ipv6_setup=0
Sat Oct 24 12:10:58 2015 /sbin/ip link set dev tun0 up mtu 1500
Sat Oct 24 12:10:58 2015 /sbin/ip addr add dev tun0 local 10.10.10.6 peer 10.10.10.5
Sat Oct 24 12:10:59 2015 Initialization Sequence Completed

Exit this with Ctrl+c

Enable VPN at boot

sudo systemctl enable openvpn@Japan

Setup Routing and NAT

Enable IP Forwarding:

echo -e '\n#Enable IP Routing\nnet.ipv4.ip_forward = 1' | sudo tee -a /etc/sysctl.conf
sudo sysctl -p

Setup NAT fron the local LAN down the VPN tunnel:

sudo iptables -t nat -A POSTROUTING -o tun0 -j MASQUERADE
sudo iptables -A FORWARD -i tun0 -o eth0 -m state --state RELATED,ESTABLISHED -j ACCEPT
sudo iptables -A FORWARD -i eth0 -o tun0 -j ACCEPT

Make the NAT rules persistent across reboot:

sudo apt-get install iptables-persistent

The installer will ask if you want to save current rules, select Yes

If you don't select yes, that's fine, you can save the rules later with sudo netfilter-persistent save

Make the rules apply at startup:

sudo systemctl enable netfilter-persistent

VPN Kill Switch

This will block outbound traffic from the Pi so that only the VPN and related services are allowed.

Once this is done, the only way the Pi can get to the internet is over the VPN.

This means if the VPN goes down, your traffic will just stop working, rather than end up routing over your regular internet connection where it could become visible.

sudo iptables -A OUTPUT -o tun0 -m comment --comment "vpn" -j ACCEPT
sudo iptables -A OUTPUT -o eth0 -p icmp -m comment --comment "icmp" -j ACCEPT
sudo iptables -A OUTPUT -d 192.168.1.0/24 -o eth0 -m comment --comment "lan" -j ACCEPT
sudo iptables -A OUTPUT -o eth0 -p udp -m udp --dport 1198 -m comment --comment "openvpn" -j ACCEPT
sudo iptables -A OUTPUT -o eth0 -p tcp -m tcp --sport 22 -m comment --comment "ssh" -j ACCEPT
sudo iptables -A OUTPUT -o eth0 -p udp -m udp --dport 123 -m comment --comment "ntp" -j ACCEPT
sudo iptables -A OUTPUT -o eth0 -p udp -m udp --dport 53 -m comment --comment "dns" -j ACCEPT
sudo iptables -A OUTPUT -o eth0 -p tcp -m tcp --dport 53 -m comment --comment "dns" -j ACCEPT
sudo iptables -A OUTPUT -o eth0 -j DROP

And save so they apply at reboot:

sudo netfilter-persistent save

If you find traffic on your other systems stops, then look on the Pi to see if the VPN is up or not.

You can check the status and logs of the VPN client with:

sudo systemctl status openvpn@Japan
sudo journalctl -u openvpn@Japan

Configure Other Systems on the LAN

Now we're ready to tell other systems to send their traffic through the Raspberry Pi.

Configure other systems' network so they are like:

  • Default Gateway: Pi's static IP address (eg: 192.168.1.2)
  • DNS: Something public like Google DNS (8.8.8.8 and 8.8.4.4)

Don't use your existing internet router (eg: 192.168.1.1) as DNS, or your DNS queries will be visible to your ISP and hence may be visible to organizations who wish to see your internet traffic.

Optional: DNS on the Pi

To ensure all your DNS goes through the VPN, you could install dnsmasq on the Pi to accept DNS requests from the local LAN and forward requests to external DNS servers.

sudo apt-get install dnsmasq

You may now configure the other systems on the LAN to use the Pi (192.168.1.2) as their DNS server as well as their gateway.

@syrusfem
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syrusfem commented Nov 22, 2020

Hello, this is a great tutorial.
I followed the istructions including the dsnmasq setup and it works great but i can't block call to hard coded DNS from clients.
If from a client i call this command : nslookup example.com 208.67.222.222 i have a response from the remote DNS server.
I tried to use : sudo iptables -t nat -A PREROUTING -i eth0 -p tcp -m tcp --dport 53 -j DNAT --to 127.0.0.1 but it does not reroute hard coded DNS calls from clients to the raspberry dnsmasq.
Any idea of how i could block or better reroute to local dnsmasq these calls?
Thanks!

@AaronDavidSchneider
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Thank you for this awesome guide! Is it possible to still run an openvpn server simultaneously on the same device?
E.g: Use this method to connect all network devices to the VPN on a VCS and have a vpn server (using pivpn) to be able to connect from outside to the home network.

@yalopov
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yalopov commented Dec 3, 2020

I tried this with both ExpressVPN and Surfshark using Arch Linux with no success.

I was able to connect other devices through this "router" host by setting them router host's IP as gateway IP and DNS servers manually, it worked but I was getting DNS leaks.

After doing some research I found this info (https://wiki.archlinux.org/index.php/OpenVPN#DNS), it says it's necessary to use a script to let OpenVPN to update DNS name servers after establish or finalize a connection, I tried openvpn-update-resolv-conf-git, it updated my /etc/resolv.conf file and fixed the DNS leaks in the router host but other hosts connecting through would still have that issue.

It seems that script works locally, but it's needed to set up a DNS server to let other devices know the current VPN's DNS nameservers (as DNS servers could change as VPN connects to different servers), so I tried to set up a BIND DNS server on the router host and configured it to retrieve /etc/resolv.conf name servers using openresolv.
That way the openvpn-update-resolv-conf script would try to update DNS nameservers using openresolv's resolvconf and that would update the BIND server config to resolve DNS queries to other devices.

It tried to work but other devices DNS queries would hang out after a few seconds, I tried to debug BIND but didn't have any luck.

It didn't work but It was fun at least.

@syrusfem
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syrusfem commented Dec 6, 2020

A thing i noticed in my setup is that sometimes under heavy traffic for long time (say a week) sometimes clients lost internet connection .
I have setup a reboot once a week: with this line in crontab: 0 5 * * 1 sudo shutdown -r now for a refresh of the system .
UPDATE
As an alternative and upgrate to the weekly reboot now i use the following script :

#!/bin/bash

ping -c2 google.com  > /dev/null

if [ $? -ne 0 ]
    then
        echo "No network connection , restarting"
        reboot
       
    else
        echo "ok"
fi

saved as file executable (using chmod +x) and started every 5 minutes with crontab.
The script check if the system could reach google.com, if not start a reboot of the system.
The script i use is discussed in these pages:
https://www.raspberrypi.org/forums/viewtopic.php?t=265337
https://superuser.com/questions/378549/can-i-automatically-reboot-if-disconnected-from-the-internet

For DNS leakage i have problems only for hard coded DNS of clients (clients that connect using a DNS IP ignoring the fixed VPN DNS i set up on them) other than that i have no other leaks.

@squeeeb
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squeeeb commented Dec 20, 2020

Beautiful - thanks!

@JeisonSanches
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Thank you for this awesome guide! Is it possible to still run an openvpn server simultaneously on the same device?
E.g: Use this method to connect all network devices to the VPN on a VCS and have a vpn server (using pivpn) to be able to connect from outside to the home network.

Any news? I'm trying the exact same thing.

@kinduff
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kinduff commented Dec 14, 2021

@JeisonSanches Should be possible, since the server will route clients through the device, they should connect through the VPN.

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