Unlike CentOS, ubuntu doesn’t provide a nice tool to set default routes when there are more than 1 ethernet interfaces are connected at the same time. It is possible to set up a static route with post-up but it is still difficult to do if the DHCP range is dynamic and you can’t accurately determine the proper gateway.<\/p>\n
I was able to reliably implement it with the following settings.
\nOpen \/etc\/network\/interfaces file and
\nAdd the following line to all other interfaces that does NOT act as a default gateway.<\/p>\n
post-up route del default dev $IFACE<\/pre>\n<\/p>\n
This code, instead of setting a default route, basically removes undesired default routes as the device goes up.<\/p>\n
Example configuration when you want to use ens160 as default route:<\/p>\n
auto ens172\r\niface ens172 inet dhcp\r\npost-up route del default dev $IFACE\r\n\r\nauto ens192\r\niface ens192 inet dhcp\r\npost-up route del default dev $IFACE\r\n\r\n# The primary network interface\r\nauto ens160\r\niface ens160 inet dhcp\r\n<\/pre>\n","protected":false},"excerpt":{"rendered":"Unlike CentOS, ubuntu doesn’t provide a nice tool to set default routes when there are more than 1 ethernet interfaces are connected at the same time. It is possible to set up a static route with post-up but it is still difficult to do if the DHCP range is dynamic and you can’t accurately determine … Continue reading Setting primary interface in ubuntu<\/span>