Hi. On Tue, Oct 03, 2017 at 02:32:29AM -0400, Gene Heskett wrote: > Greetings; > > Confusion still reigns here. > For instance: > oot@coyote:~# ip m l eth0 > 2: eth0 > link 01:00:5e:00:00:01 > link 33:33:00:00:02:02 > link 33:33:00:00:00:01 > link 01:00:5e:00:00:fb > link 33:33:ff:62:fc:bb > link 33:33:00:00:00:fb > inet 224.0.0.251 > inet 224.0.0.1 > inet6 ff02::fb > inet6 ff02::1:ff62:fcbb > inet6 ff02::202 > inet6 ff02::1 > inet6 ff01::1
So, multicasts. Ok. > But add - -r so its supposed to show names, and get: > 2: eth0 > link 01:00:5e:00:00:01 > link 33:33:00:00:02:02 > link 33:33:00:00:00:01 > link 01:00:5e:00:00:fb > link 33:33:ff:62:fc:bb > link 33:33:00:00:00:fb > inet (5 second pause) 224.0.0.251 > inet all-systems.mcast.net > inet6 ff02::fb > inet6 ff02::1:ff62:fcbb > inet6 ff02::202 > inet6 ip6-allnodes > inet6 ff01::1 > Which, according to the manpage and my interpretation, should resolv the > names those 6 (mac?) addresses belong to. No, it should not. It means: -r, -resolve use the system's name resolver to print DNS names instead of host addresses. So, in plain English - if it is an IP address - it will be resolved. If it is an IPv6 address - it will be resolved too. At least ip will try to do so via /etc/hosts, DNS requests and other name resolution methods all according to your /etc/nsswitch.conf. To translate MACs to IPs you need to do ARP requests (ICMPv6 if you need IPv6 addresses). Try "ip -r n s" instead. > So while its seemingly working at the net hardwares speed, I think its > telling me I am miss-configured somehow. There are not any ipv6 addresses in > the hosts file that would translate to the same name as the machines given > name. I tried that several years ago and it caused errors at the time. Run "tcpdump -nvi any udp port 53 or tcp port 53 or udp port 5353". Run "ip -r m l eth0" alongside with it. Watch the result. Frankly I'm not surprised that it failed to resolve 224.0.0.251. Nobody sane would add a DNS record for this anyway. Reco