Raspberry Pi as a router

One possible way to setup a Raspberry Pi as a router is to flash OpenWRT on an SD card. I will try that when I have an extra SD card. But for now I wanted to have it work as a router and keep using Raspbian at the same time.

This method is quite simple. It invloves adding iptable rules and optionally using sshuttle to make it work as a proxy. All devices connected to this wifi network will have their traffic proxied through the Pi. Here is the overall setup of my LAN (the powerline extender is optional indeed - I have to use it due to the topology of our house):

ISP modem ⇔ Raspberry Pi ⇔ Powerline extender ⇔ Powerline Wifi

I connected eth0 to the ISP modem, and eth1 (via a USB-Ethernet adapter) to the powerline extender. Here is a script to setup traffic forwarding in Raspberry Pi:

# eth0 is connected to ISP modem
# eth1 is connected to LAN extender

# This should work, otherwise try editing /etc/sysctl.conf
echo 1 > /proc/sys/net/ipv4/ip_forward
sysctl -p

# Always accept loopback traffic
iptables -A INPUT -i lo -j ACCEPT

# We allow traffic from the LAN side
iptables -A INPUT -i eth0 -j ACCEPT

# Allow established connections
iptables -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT

# Masquerade.
iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE

# fowarding
iptables -A FORWARD -i eth0 -o eth1 \
         -m state --state RELATED,ESTABLISHED -j ACCEPT

# Allow outgoing connections from the LAN side.
iptables -A FORWARD -i eth1 -o eth0 -j ACCEPT

Optionally, start sshuttle like this:

sshuttle --dns -vr host \
    -l          \
    -x   \

I exclude, so I could still SSH into Pi without sshuttle proxying my connection to the host.

It is very difficult to find a Raspberry Pi where I live. I would like to thank my friends @gluegadget, @cubny and @artlesshand who got me this Raspberry Pi.