Wireless

• WPA/WPA2 -- Wi-Fi Protected Access & Wi-Fi Protected Access V2) are security protocols for encrypting Wi-Fi communication. WPA has been hacked and should no longer be considered secure.
• WPA2 is also called RSN
• WPA/WPA2 (RSN) Enterprise -- requires a RADIUS server and is appropriate for large entities
• WPA/WPA2 (RSN) Personal (a.k.a. WPA-PSK or WPA2-PSK) -- uses pre-shared keys. Appropriate for residential and small business settings.
• WEP -- Wired Equivalency Protocol is another encryption mechanism. It has also been hacked and should no longer be considered secure.
• WPS -- Wi-Fi Protected Set-up is a technology which allows you to easily set-up a connection to a wireless network. After your network has been established, WPS should be disabled.

How to Connect to a WPA or WP2(RSN) network

• lsusb list usb devices
• iw list list wireless devices
• Create a virtual interface -- iw phy phy0 interface add <name> type <type>. For instance iw phy phy0 interface add wlan0 type station -- station connects to an AP (access point)
• To delete a virtual interface -- iw dev wlan0 del

Here are the various types (modes):

• AP (acess point) mode. To use AP mode, you need to use hostapd.
• managed (station) mode. Connects to an AP
• ibss (ad-hoc). A wireless network without the need of an AP
• mp (mesh). A wireless network in which nodes can forward to other nodes -- which is useful if the nodes are sparsely populated.
• monitor mode. No packets are transmitted. All packets are handed over to the host machine unfiltered.
• wds mode.

Check device status. Up or Down. ip link show wlan0 -- should show that the device is down -- i.e. UP is NOT seen between the parenthesis

Bring the device Up. ip link set wlan0 up -- requires root access.

Check device status. ip link show wlan0 -- you should now see that the device is UP -- i.e. UP is seen between the parenthesis

Check the connection status. iw wlan0 link -- which should report that you are NOT connected to a network

Scan available Wi-Fi networks. iw wlan0 scan -- note the SSID (network ID) and security protocol (WPA2 or RSN)

wpa_passphrase <SSID> >>/etc/wpa_supplicant.conf. Press ENTER and enter the network password followed by ENTER. This requires root access.

wpa_supplicant -B -D wext -i wlan0 -c /etc/wpa_suppllicant.conf. -B to run in the background (omit this for debugging). -D for the wireless driver. wext is a generic driver.

Check the connection status. iw wlan0 link -- which should report that you are now connected to a network

Obtain IP address via DHCP. chclient wlan0

Test external connectivity. ping www.google.com

Hostapd

• Hostapd is a user space daemon for access point servers.