Linux/Wifi
< Linux
Common Tasks
Wireless interface tools:
ifconfig # set interface ip address and up/down state iwconfig # configure wireless settings (SSID, key, mode) iwlist # scan wireless dhclient # dhcp client
Set ESSID:
iwconfig [interface] essid [essid] iwconfig eth1 essid toast
Set managed mode:
# note: interface may need to be down to change (ifconfig eth1 down) iwconfig eth1 mode Managed
Set WEP key:
iwconfig eth1 key 0123-4567-89 iwconfig eth1 key off
WPA:
# type password, hit enter wpa_passphrase [SSID] >> /etc/wpa_supplicant/wpa_supplicant.conf
network={
ssid="testnetwork"
#psk="testpassword"
psk=ed5b87ba31bf9d6611576f94c57e848696005ea2d5743baab976a48ed11d1b2a
}
# start wpa_supplicant daemon wpa_supplicant -c /etc/wpa_supplicant/wpa_supplicant.conf -i wlan0 -D madwifi # debug mode: wpa_supplicant -c wpa.conf -i wlan0 -d
DHCP client:
dhclient [interface] # get DHCP address dhclient -r [interface] # release DHCP address dhclient [interface] -H [hostname] # get DHCP address and set hostname
Other examples:
iwconfig wlan0 mode managed iwpriv wlan0 set AuthMode=WPAPSK iwpriv wlan0 set EncrypType=TKIP iwpriv wlan0 set WPAPSK="AP's wpa-preshared key" iwconfig wlan0 essid "AP's SSID"
Scan:
iwlist [interface] scan
Common wireless interfaces:
eth1, wlan0, ath0
madwifi
See madwifi
Wireless WEP Authentication
Shared WEP key:
iwconfig ath0 key <yourkey> # operating in a restricted, shared-key environment iwpriv ath0 authmode 2 # operating in open system key (which is often considered more secure) iwpriv ath0 authmode 1
Connecting to AP
Connecting to an open AP:
iwconfig ath0 essid "eddie" iwconfig ath0 ap 00:06:25:E8:3A:05
Connect to first available open AP:
iwconfig ath0 ap any iwconfig ath0 ap auto
Connecting with DHCP
DHCP Connection:
dhclient ath0 dhcpcd ath0
Connect without DHCP
ifconfig ath0 <IP address> netmask <netmask> up route add default gw <gateway hostname> route add default gw <gateway address> vi /etc/resolv.conf search t0e.org nameserver 10.10.10.1
CentOS interface setup
/etc/sysconfig/network-scripts/ifcfg-ath0
DEVICE=ath0 BOOTPROTO=dhcp HWADDR=00:0F:20:95:6A:9A ONBOOT=no DHCP_HOSTNAME=kencent
Ubuntu interface setup
/etc/network/interfaces:
iface lo inet loopback
auto lo
iface eth0 inet dhcp
iface wlan0 inet manual
allow-hotplug wlan0
wpa-roam /etc/wpa_supplicant/wpa_supplicant.conf
iface default inet dhcp
Connecting to an AP with WEP
using shared WEP key:
iwpriv ath0 authmode 2
using open WEP key (which is often considered more secure):
iwpriv ath0 authmode 1
Specify WEP key:
iwconfig ath0 key <wep key (in hex)> iwconfig ath0 key <s:ASCII string of key>
Connecting to an AP with WPA
Make PSK:
wpa_passphrase My_WPA_Protected_AP_ESSID "Some_Decent_PassPhrase_of_up_64_Characters" >> /etc/wpa_supplicant.conf
Edit /etc/wpa_supplicant.conf and add the lines into the network section created above:
key_mgmt=WPA-PSK # proto=WPA proto=RSN
Uncomment the proto=WPA line (and comment out the RSN line) to enable WPA. Leave as is for WPA2 (stronger encryption).
Secure:
chmod 640 /etc/wpa_supplicant.conf
Full example:
modprobe ath_pci # if running pre-r1408 Madwifi code, then also: wlanconfig ath0 create wlandev wifi0 wlanmode sta iwconfig ath0 essid "My_WPA_Protected_AP_ESSID" ifconfig ath0 192.168.0.100 up /usr/local/bin/wpa_supplicant -dd -Dmadwifi -iath0 -c/etc/wpa_supplicant.conf
See if connected:
iwconfig ath0
Automate wpa_supplicant:
#!/bin/sh modprobe ath_pci (If running pre-r1408 Madwifi code, then also: wlanconfig ath0 create wlandev wifi0 wlanmode sta) iwconfig ath0 essid "My_WPA_Protected_AP_ESSID" ifconfig ath0 192.168.0.100 up wpa_supplicant -Bw -Dmadwifi -iath0 -c/etc/wpa_supplicant.conf
old note:
wpa_supplicant -Bw -Dwext -iath0 -c/etc/wpa_supplicant.conf # if you are using a Linux version smaller than 2.6.14 wpa_supplicant -Bw -Dmadwifi -iath0 -c/etc/wpa_supplicant.conf
References:
wifi init.d
#!/bin/sh
#
# chkconfig: - 99 01
# description: Starts and stops the Wireless
#
# lock: /var/run/wifi
# config: /etc/sysconfig/wifi
# config: /etc/wpa_supplicant.conf
# Source function library.
if [ -f /etc/init.d/functions ] ; then
. /etc/init.d/functions
elif [ -f /etc/rc.d/init.d/functions ] ; then
. /etc/rc.d/init.d/functions
else
exit 1
fi
# /etc/sysconfig/wifi
# WIFI_SSID=ssid
# WIFI_DHCP=yes
# WIFI_AUTH=wpa|wep
if [ ! -e /etc/sysconfig/wifi ] ; then
echo "ERROR: /etc/sysconfig/wifi is missing"
exit 1
else
. /etc/sysconfig/wifi
fi
# WPA
# wpa_passphrase "My_WPA_Protected_AP_ESSID" "Some_Decent_PassPhrase_of_up_64_Characters" >> /etc/wpa_supplicant.conf
LOCKFILE=/var/run/wifi
case "$1" in
start)
echo -n "Starting wifi: "
if [ -e $LOCKFILE ] ; then
echo -n "Wifi already running"
failure ; echo ; exit 1
fi
touch $LOCKFILE
modprobe ath_pci
iwconfig ath0 essid "${WIFI_SSID}"
if [ "${WIFI_AUTH}" = "wpa" ] ; then
wpa_supplicant -Bw -Dmadwifi -iath0 -c/etc/wpa_supplicant.conf
else
echo -n "code not written yet!"
failure ; echo ; exit 1
fi
if [ "${WIFI_DHCP}" = "yes" ] ; then
dhclient ath0 &> /dev/null
if [ "$?" != "0" ] ; then
echo -n "unable to obtain ip address!"
failure ; echo ; exit 1
fi
else
echo "code not written yet!"
failure ; echo ; exit 1
fi
success ; echo ; exit 0
;;
stop)
echo -n "Stopping wifi:"
rm -f $LOCKFILE
dhclient -r ath0 &>/dev/null
killall wpa_supplicant &>/dev/null
modprobe -r ath_pci
success ; echo ; exit 0
;;
restart)
$0 stop
$0 start
;;
status)
if [ -e $LOCKFILE ] ; then
echo "Wifi is running"
exit 1
else
echo "Wifi is stopped"
exit 1
fi
;;
*)
echo $"Usage: $0 {start|stop|restart|status}"
exit 2
esac
Notes
Restart network:
service network restart
Shut down madwifi:
ifconfig ath0 down ifconfig wifi0 down
iwconfig ath0 mode master iwconfig ath0 essid paradiso iwconfig ath0 channel 9 iwpriv ath0 mode 2 ifconfig ath0 up
References:
WPA with Linux
wpa_passphrase YOURSSID yourpassphrase > /etc/wpa_supplicant.conf chmod 640 /etc/wpa_supplicant.conf wpa_supplicant -Bw -Dwext -iath0 -c/etc/wpa_supplicant.conf # or use -Dmadwifi instead of -Dwext
References: