Since I’m a lazy git, I want my laptop to automatically switch back & forth between my wired and wireless interfaces. Seems that stuff like Network Manager can do that for you, but it’s not really my thing. I don’t like stuff where you need a GUI to configure it, a duplicaton of network configuration, and it also tends to hang my machine. No idea why, though.
After an afternoon of fiddling around with several things, I came up with the recipe:
1 portion ifplugd, a good mix of ifupdown configuration with guessnet mappings, and some home-grown scripts. Mix well, and let simmer over a hot stove for half an hour. ;)
- Install ifplugd and guessnet:
apt-get install ifplugd guessnet
- Configure the interface you want ifplugd to monitor. For me, this is eth0 (wired ethernet). You can do this by editing
/etc/default/ifplugdand adding eth0 in the
Restart ifplugd (
- Edit your
/etc/network/interfacesfile the way you like it. I’m using multiple wireless entries with guessnet:
mapping ath0 script guessnet-ifupdown map verbose: false map debug: false map autofilter: true iface ath0-work inet dhcp test wireless essid WORK wpa-ssid WORK wpa-key-mgmt WPA-PSK wpa-proto WPA wpa-psk "***" wpa-driver wext iface ath0-home inet dhcp test wireless essid HOME wpa-ssid HOME wpa-key-mgmt WPA-PSK wpa-proto WPA wpa-psk "***" wpa-driver wext
For syntax info, see
- Replace the script in
/etc/ifplugd/action.dwith something more usable. The installed script only calls ifup or ifdown depending on what’s happening. What we want is to ifdown the interface, and ifup the other.
Something like this:
#!/bin/sh set -e WIRED_INTERFACE="eth0" WIFI_INTERFACE="ath0" WIFI_MODULE="ath_pci" IFUPDOWN_STATE="/etc/network/run/ifstate" if [ $# -ne 2 ]; then echo "Incorrect usage!" echo "$0:
" exit 1 fi case "$2" in up) if [ "$1" = $WIRED_INTERFACE ]; then # Wired interface is going up, bring wireless down # if it is active. WIFI_MODULE_LOADED=$(lsmod | grep ^$WIFI_MODULE | wc -l) if [ $WIFI_MODULE_LOADED -eq 1 ]; then /sbin/ifdown $WIFI_INTERFACE /sbin/rmmod $WIFI_MODULE fi /sbin/ifup $WIRED_INTERFACE else /sbin/ifup $1 fi ;; down) if [ "$1" = $WIRED_INTERFACE ]; then # Wired interface is going down, bring up the # wireless one. /sbin/ifdown $WIRED_INTERFACE /sbin/modprobe $WIFI_MODULE /sbin/ifconfig $WIFI_INTERFACE up sleep 5 /sbin/ifup $WIFI_INTERFACE WIFI_CONFIGURED=$(grep ^$WIFI_INTERFACE $IFUPDOWN_STATE | wc -l) if [ $WIFI_CONFIGURED -eq 0 ]; then # Interface was not configured, bring it back down # to save power /sbin/rmmod $WIFI_MODULE fi else /sbin/ifdown $1 fi ;; esac
Now, every time ifplugd configures up eth0, ath0 is automatically deconfigured, and vice versa.
The actual configuration of the interfaces is still in
/etc/network/interfaces, so you can still handle it by hand if you want to.