I would like to have multiple NICs (eth0 and wlan0) in the same subnet and to serve as a backup for the applications on the host if one of the NICs fail. For this reason I have created an additional routing table. This is how /etc/network/interfaces looks:
netstat -s prints out a lot of very detailed protocol statistics like number of TCP reset messages received or number of ICMP “echo request” messages sent or number of packets dropped because of a missing route.
Linux as router: I have 3 Internet providers, each with its own modem.
Manpage of ss says:
In Linux, is there any difference between after-ip link down-condition and real link absence (e.g. the switch’s port burned down, or someone tripped over a wire).
By difference I mean some signs in the system that can be used to distinguish these two conditions.
E.g. will routing table be identical in these two cases? Will ethtool or something else show the same things? Is there some tool/utility which can distinguish these conditions?