1, when the call ' ifconfig eth0 down ' command shuts down the network device eth0, it will have the following effects:
- All IP addresses configured on the NIC will be invalidated and removed (tested on Ubuntu 14.04, IP will not be removed, and still exist after reactivation)
- Any connections that are associated with IP on the NIC will be compromised
- All routes that need to pass through the network card will be removed from the routing table
- The link layer device fails
Note: If the default route is also emitted through the device eth0, the default route is also removed
Similarly, when you turn on the network card device, you have the following effects:
- Link Layer device is reactivated
- The required IP address is assigned to a specific interface
- All local, network, and broadcast routes that are derived from IP configuration are added to the routing table
Linux User Space Network Configuration tool tips
