On 11/08/2019 21.20, James Knott wrote:
On 2019-08-11 03:04 PM, Carlos E. R. wrote:
What I have found today is "ip neighbour show". It does not show my printer IPv6 address, though, it shows other fe80's.
Fire up Wireshark and filter on ICMP6. It will show neighbor and router advertisements & solicitations. If you don't see your printer, it is not even using the link local address, as the advertisements are mandatory.
First try this afternoon: Telcontar:~ # ip neighbour show 192.168.1.57 dev eth0 lladdr 44:09:b8:42:c9:44 STALE 192.168.1.16 dev eth0 lladdr 4c:cc:6a:61:50:a1 REACHABLE 192.168.1.1 dev eth0 lladdr f8:8e:85:64:78:f2 REACHABLE 192.168.1.2 dev eth0 lladdr 00:01:02:03:04:05 REACHABLE 192.168.1.3 dev eth0 lladdr 00:1e:0b:08:4c:cb STALE <============ 192.168.1.126 dev eth0 lladdr a0:d3:7a:a5:1d:4c STALE 192.168.1.8 dev eth0 lladdr 88:b6:27:01:72:63 STALE fe80::fa8e:85ff:fe64:78f2 dev eth0 lladdr f8:8e:85:64:78:f2 router STALE fe80::4ecc:6aff:fe61:50a1 dev eth0 lladdr 4c:cc:6a:61:50:a1 STALE fc00::16 dev eth0 lladdr 4c:cc:6a:61:50:a1 STALE Telcontar:~ # It did not show on IPv6. Later, after looking at its config page with firefox: Telcontar:~ # ip neighbour show | grep -i 4C:CB 192.168.1.3 dev eth0 lladdr 00:1e:0b:08:4c:cb STALE fe80::21e:bff:fe08:4ccb dev eth0 lladdr 00:1e:0b:08:4c:cb STALE Telcontar:~ # Telcontar:~ # ping -c 2 FE80::21E:BFF:FE08:4CCB%eth0 PING FE80::21E:BFF:FE08:4CCB%eth0(fe80::21e:bff:fe08:4ccb%eth0) 56 data bytes 64 bytes from fe80::21e:bff:fe08:4ccb%eth0: icmp_seq=1 ttl=64 time=0.352 ms 64 bytes from fe80::21e:bff:fe08:4ccb%eth0: icmp_seq=2 ttl=64 time=0.351 ms --- FE80::21E:BFF:FE08:4CCB%eth0 ping statistics --- 2 packets transmitted, 2 received, 0% packet loss, time 1026ms rtt min/avg/max/mdev = 0.351/0.351/0.352/0.018 ms Telcontar:~ # Telcontar:~ # ip neighbour show | grep -i 4C:CB 192.168.1.3 dev eth0 lladdr 00:1e:0b:08:4c:cb STALE fe80::21e:bff:fe08:4ccb dev eth0 lladdr 00:1e:0b:08:4c:cb REACHABLE Telcontar:~ # Telcontar:~ # arp | grep -i 4C:CB bilbo.valinor ether 00:1e:0b:08:4c:cb C eth0 Telcontar:~ #
Those advertisements are an essential part of how IPv6 works. On IPv4, you have to use ARP to map an IP address with a MAC. You don't have to with IPv6, as the advertisements always happen. However, you can trigger the advertisement sooner, by using solicitations. There is no similar mechanism in IPv4 to identify routers, other than perhaps multicast ping.
Good, but this printer is not doing it, apparently. Call the police? :-D I think it may do some own HP broadcast instead, I have noticed it in logs. -- Cheers / Saludos, Carlos E. R. (from 15.0 x86_64 at Telcontar)