Two methods can be used to bring interfaces up or down.
From the command line, use:
ip link set dev <interface> up ip link set dev <interface> down Example: ip link set dev eth0 up ip link set dev eth0 down
From the command line, use:
/sbin/ifconfig <interface> up /sbin/ifconfig <interface> down Example: /sbin/ifconfig eth0 up /sbin/ifconfig eth0 down