$ ip -4 neigh show dev eno1 184.108.40.206 FAILED 220.127.116.11 FAILED 18.104.22.168 FAILED 22.214.171.124 FAILED 126.96.36.199 FAILED 188.8.131.52 FAILED
How could these weird ip neighbour (ARP) entries be appearing on my Ethernet interface?
eno1 is an Ethernet interface. It is not currently connected. Based on
journalctl -b | grep eno1, I do not think I have connected it at all during this boot! I do not use a static IP. I have not changed my IP settings manually during this boot. The network settings are all managed by NetworkManager. I have connected only to my home networks, which use addresses in the private range 172.16.0.0 - 172.31.255.255 only.
For example on my current wireless connection, I see that my address is 172.16.8.139/24. That says the network prefix is 24 bits, and so ARP resolution should be limited to the range 172.16.8.0 - 172.16.8.255.
$ ip -4 addr show dev wlp2s0 4: wlp2s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP group default qlen 1000 inet 172.16.8.139/24 brd 172.16.8.255 scope global dynamic noprefixroute wlp2s0 valid_lft 39441sec preferred_lft 39441sec $ ip -4 neigh show dev wlp2s0 172.16.8.1 lladdr 74:44:01:86:42:d6 REACHABLE
$ lsb_release -d Description: Fedora release 29 (Twenty Nine) $ rpm -q NetworkManager dhcp-client NetworkManager-1.12.6-5.fc29.x86_64 dhcp-client-4.3.6-28.fc29.x86_64
My router is OpenWRT 18.06.1, so the DHCP server is