I want to achieve dynamic interface change between eth0 and wlan0, one solution I am looking into is to change interface metric. Different than this question, I don't want to make any change to /etc/networking/interfaces, so I used ifmetricto change interface metrics.
$ netstat -ren
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
0.0.0.0 192.168.1.1 0.0.0.0 UG 0 0 0 eth0
169.254.0.0 0.0.0.0 255.255.0.0 U 0 0 0 eth0
192.168.1.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0
192.168.1.0 0.0.0.0 255.255.255.0 U 1000 0 0 wlan0
$ sudo ifmetric eth0 1000
$ sudo ifmetric wlan0 0
$ netstat -ren
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
0.0.0.0 192.168.1.1 0.0.0.0 UG 1000 0 0 eth0
169.254.0.0 0.0.0.0 255.255.0.0 U 1000 0 0 eth0
192.168.1.0 0.0.0.0 255.255.255.0 U 0 0 0 wlan0
192.168.1.0 0.0.0.0 255.255.255.0 U 1000 0 0 eth0
But I don't know how to put this metric to effect, i.e. how to refresh the routing table to reflect metric and let wlan0 become the primary interface?
