Network configuration for Wii U GamePad <-> PC¶

The Wii U GamePad communicates with other devices via the use of a slightly obfuscated version of Wi-Fi 802.11n and WPA2 AES-CCMP. Luckily, the required modifications for support of this obfuscated Wi-Fi protocol can be applied in userland without any kernel modification.

Using libdrc to communicate with a Wii U GamePad however also requires the host computer to get some information from its Wi-Fi interface which is not exported by default on Linux. For this purpose, a kernel module needs to be built and loaded on the machine to provide the required information.

Required hardware¶

Connecting a Wii U GamePad to a computer requires compatible Wi-Fi hardware. Any Wi-Fi NIC that can create access points on 5GHz 802.11 channels could potentially work. In practice, the following drivers/NICs were tested:

rt2800usb: works with Linux >= 3.12
ath9k/carl9170: works with some caveats (communication might desync more often because of a TSF drifting issue)

Linux kernel patch¶

A very simple Linux kernel patch is required to export the Wi-Fi NIC Time Synchronization Function (TSF) to userland. A patched version of the mac80211 Linux module can be found on the memahaxx/drc-mac80211 repository. It is based on Linux 3.12.3 but the patch should apply cleanly to most recent Linux versions (e.g. Ubuntu > 13.10).

To check if the patched module is being used, try:

test -f /sys/class/net/$WLANIFACE/tsf && echo ok

Pairing the Wii U GamePad with a computer¶

There are two methods to pair a GamePad with a computer:

Use a GamePad that has previously paired with a Wii U console. Connect the computer in client mode to the Wii U console to do the WPS negotiation and obtain the same details.
1. Download and build memahaxx/drc-hostap. Make sure CONFIG_WPS and CONFIG_TENDONIN are enabled for both hostapd and wpa_supplicant. Ensure that no other program (e.g. a system wpa_supplicant or NetworkManager is currently managing the target interface wlanX).
2. Make a new config get_psk.conf file consisting of these two lines:
```
ctrl_interface=/var/run/wpa_supplicant_drc
update_config=1
```
3. In a terminal, execute:
```
sudo ./wpa_supplicant -Dnl80211 -i wlanX -c get_psk.conf
```
  Replace wlanX with the correct network interface.
4. In a separate terminal, execute:
```
sudo ./wpa_cli -p /var/run/wpa_supplicant_drc
```
5. Press the sync button twice on your Wii U console.
6. In wpa_cli, type:
```
scan
```
7. Once you see <3>CTRL-EVENT-SCAN-RESULTS type:
```
scan_results
```
8. On the returned list, you should see an entry with an SSID along the lines of WiiUAABBCCDDEEFF_STA1. Take a note of the BSSID for this access point.
9. In wpa_cli, type:
```
wps_pin BSSID PIN
```
  where BSSID is the BSSID you noted in the previous step, and PIN is the PIN you calculated from the Pairing information.
10. You should see some output, including <3>WPS-CRED-RECEIVED followed by <3>WPS-SUCCESS.
11. Ctrl+C wpa_supplicant.
12. To see your PSK, type:
```
cat get_psk.conf
```
Have a computer host WPS and sync a GamePad directly with it. TODO: write instructions for this method.

Setting up the Wi-Fi access point¶

First of all, build the patched hostapd version available from memahaxx/drc-hostap:

git clone https://bitbucket.org/memahaxx/drc-hostap
cd drc-hostap
cp conf/hostapd.config hostapd/.config
cd hostapd
make -j4

Adapt the example configuration file from conf/wiiu_ap_normal.conf:

Change the network interface name
Change the network SSID
Change the PSK used for the network WPA2 security

Stop anything that might conflict with hostapd (for example, NetworkManager is a known offender unless configured specifically to avoid this). Then start the access point:

sudo ./hostapd -dd ../conf/wiiu_ap_normal.conf

If everything worked well, hostapd should be waiting for devices to connect instead of exiting immediately.

Make sure that no network interface is using the 192.168.1.0/24 network (it is used for communication with the GamePad), then configure the interface:

sudo ip a a 192.168.1.10/24 dev $IFACE
sudo ip l set mtu 1800 dev $IFACE

Starting a DHCP server¶

The GamePad uses DHCP to get an IP address from the Wii U or the PC it is connected to. This IP address should always be 192.168.1.11. Any simple DHCP server should work, but we recommend using netboot, a very simple, self-contained DHCP server.

Using netboot, the following command line should work (with the propre MAC address of the GamePad):

./netboot 192.168.1.255 192.168.1.10 192.168.1.11 aa-bb-cc-dd-ee-ff

From there, when powering on the GamePad, it should get an IP from netboot and start sending packets to the computer. Using libdrc demos should work.

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