Making a Wifi router from your RPi and force traffic of your Kodi through it

Sometimes, you can run out of bandwidth in your ethernet connected home network. Yet, connecting to a Wifi hotspot somewhere and serving other devices in your network that are bandwidth intensive (like your Kodi) can overcome this issue.

I have the following devices in scope for this:

• My regular Internet router is connected through a wired connection (Internal network 192.168.0.0/24)
• A RPi1 that is connected through eth0 (wired) to the home network (IP 192.168.0.30). It has also a Wifi interface wlan0 that is connected to the public internet.
• Another RPi2 that is serving Kodi to a TV also connected through eth0 to the home network (IP 192.168.0.40).

RPi1 will be the router that will connect to the Internet through wlan0. RPi2 will be configured to route all of the Internet requests to RPi1 over wired LAN.
Please note that an alternative way to configure Wifi on a RPi (e.g. serving Kodi from OSMC) can be found in this blogpost.

1. Configure RPi1 to access the Wifi hotspot
1. Scan your environment for the Wifi network

iwlist wlan0 scan

2. Edit the Wlan configuration

sudo vi /etc/wpa_supplicant/wpa_supplicant.conf

Add this config:

network={
ssid="ssid"
scan_ssid=1
key_mgmt=WPA-EAP
group=CCMP TKIP
eap=PEAP
identity="username"
password="password"
phase1="peapver=0"
phase2="MSCHAPV2"
}

3. Save and test your config

wpa_cli -i wlan0 reconfigure

4. Check if your wlan0 device has received an IP address

ifconfig wlan0 or wpa_cli -i wlan0 status

Output:

wlan0: flags=-28605  mtu 1500
        inet 151.164.43.34  netmask 255.255.255.0  broadcast 151.164.43.255
        ether b8:27:aa:aa:ff:c1  txqueuelen 1000  (Ethernet)
        RX packets 256109  bytes 319396252 (304.6 MiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 187107  bytes 24877570 (23.7 MiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

5. Install a cron task to regularly reconfigure the wlan0 interface if the Wifi connection gets disconnected
2. Create a router of your RPi1

vi /etc/iptables/rules.v4

Add this config:

*nat
-A POSTROUTING -s 192.168.0.0/24 -o wlan0 -j MASQUERADE
COMMIT

*filter
-A INPUT -i lo -j ACCEPT
# allow ssh, so that we do not lock ourselves
-A INPUT -i eth0 -p tcp -m tcp --dport 22 -j ACCEPT
# allow incoming traffic to the outgoing connections,
# et al for clients from the private network
-A INPUT -m state --state NEW,RELATED,ESTABLISHED -j ACCEPT
-A OUTPUT -p icmp --icmp-type 8 -m state --state NEW,ESTABLISHED,RELATED -j ACCEPT
-A INPUT -p icmp --icmp-type 0 -m state --state ESTABLISHED,RELATED -j ACCEPT
# prohibit everything else incoming
#-A INPUT -i eth0 -j DROP
COMMIT

1. Store your config

iptables-restore < /etc/iptables/rules.v4

2. Check if the rules are in effect

root@hass:~# iptables -L
Chain INPUT (policy ACCEPT)
target     prot opt source               destination         
ACCEPT     all  --  anywhere             anywhere            
ACCEPT     tcp  --  anywhere             anywhere             tcp dpt:ssh
ACCEPT     all  --  anywhere             anywhere             state NEW,RELATED,ESTABLISHED
ACCEPT     icmp --  anywhere             anywhere             icmp echo-reply state RELATED,ESTABLISHED

Chain FORWARD (policy ACCEPT)
target     prot opt source               destination         

Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination         
ACCEPT     icmp --  anywhere             anywhere             icmp echo-request state NEW,RELATED,ESTABLISHED

3. On your RPi2 add a static route to use RPi1 as the gateway for Internet traffic
1. Test what external IP is being used on RPi2

root@kodi1:/lib# curl ifconfig.me
64.160.13.75

2. Add the route

route add -net default gw 192.168.0.30 netmask 0.0.0.0 dev eth0

3. Test for your externalIP again, it should be different now

root@kodi1:/lib# curl ifconfig.me
151.164.43.34

4. Also test if you can ping to www.google.com from RPi2
5. Now all Internet traffic on RPi2 (192.168.0.40) will be routed through RPi1 (192.168.0.30)

root@kodi1:~# route -n
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
0.0.0.0         192.168.0.30    0.0.0.0         UG    0      0        0 eth0
192.168.0.0     0.0.0.0         255.255.255.255 UH    0      0        0 eth0
192.168.0.0     0.0.0.0         255.255.255.0   U     0      0        0 eth0