Raspberry as Pi Ethernet-WiFi-Bridge

The Challenge

I wanted to set up my Raspberry Pi 3 as Webcam, intranet server, and Ethernet-WiFi-Bridge. In the long run I want to use some kind of QOA/shaping on the Pi to manage my really bad internet connection (yes, 6MBit/s in a country where 82 million people live on 356 thousand square-kilometers (about 230 people per square-km).

Setup

Install additional software

apt get install hostapd bridge-utils dhcp-helper dnsutils

What do they do?

• hostapd: A daemon that sets up your WiFi as a access point, so anyone can join. Please note, that this means WiFi only. No DHCP, and therefore no DNS.
• bridge-utils: These provide the bridging you need to "connect" the ethernet and WiFi interfaces.
• dhcp-helper: DHCP uses a broadcast to the network (address) to reach the DHCP-server. Since broadcasts stay in the broadcast-domain with a TTL of 1, the won't get bridged. This is where dhcp-helper comes in. It forwards the broadcasts in all other nets (except the one specified with -b.
• dnsutils: Just to do a nslookup from time to time. You can test your DNS-setup as well as lookup with nslookup

Configuration

vi /etc/sysctl.conf

and set

net.ipv4.ip_forward=1
net.ipv6.conf.all.disable_ipv6 = 1

to TBD: EXPLANATION

vi /etc/hostapd/hostapd.conf

and set something like this:

interface=wlan0
driver=nl80211
bridge=br0
hw_mode=g
channel=7
ieee80211n=1
wmm_enabled=1
macaddr_acl=0
auth_algs=1
ignore_broadcast_ssid=0
wpa=2
wpa_key_mgmt=WPA-PSK
wpa_pairwise=TKIP
rsn_pairwise=CCMP
ssid=HeartOfGold
wpa_passphrase=42

Explanation: hostapd creates the WiFi-Access Point and creates a bridge-device br0, which he ties (only) wlan0 to.

vi /etc/dhcpcd.conf

and set something like this:

nohook wpa_supplicant
interface wlan0
static ip_address=192.168.178.58/24

Explanation: I try to omit /etc/wpa_supplicant/wpa_supplicant.conf, and configure a static IPA for wlan0. NOTE TO SELF: Might be unnecessary since the bridge is now working. TBD: CHECK!

vi /etc/network/interfaces

Don't touch this file. dhcpcd gets jealous...

Notes

Since you use a DHCP server and you manually set IPAs, you might want to reserve those IPAs in your DHCP-server configuration.

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• More like this:
  • tbd
• Footnotes