Commands I use regularly instead of using ifconfig:
# link up/down
ip link set dev eth0 up|down
# add a new address
ip addr add dev eth0 172.16.43.124/24
# to clear all IP addresses from eth0
ip addr flush dev eth0
# delete an address
ip addr del dev eth0 172.16.43.124/24
# add default route
ip route add default via 172.16.43.254
Source: news.ycombinator.com