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Two methods can be used to bring interfaces up or down
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2.1. Using "ip" Usage: # 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
2.2. Using "ifconfig" Usage: # /sbin/ifconfig <interface> up
# /sbin/ifconfig <interface> down
# Example: # ip link set dev eth0 down
# ip link set dev eth0 down