Discovered that in recent Ubuntu versions, the following is the "official" way to up and down interfaces cleanly.
/etc/network/interfacesadding your entry similar to below:
# The loopback network interface auto lo iface lo inet loopback # The primary network interface auto eth0 iface eth0 inet static address 10.1.24.30 netmask 255.255.254.0 network 10.1.24.0 broadcast 10.1.25.255 gateway 10.1.24.1 # dns-* options are implemented by the resolvconf package, if installed dns-nameservers 10.11.11.11 dns-search herpderp.com auto eth3 iface eth3 inet static address 192.168.24.29 netmask 255.255.254.0 mtu 9000
ifup eth3to bring up eth3 with its new configuration.
Want to fully clean an interface:
ifdown eth3 # For the following, sometimes flushing helps ;P # http://unix.stackexchange.com/questions/100588/using-ip-addr-instead-of-ifconfig-reports-rtnetlink-answers-file-exists-on-de ip addr flush dev eth3