Thanks for your kind responses. > You'll get better information either by trawling syslog, or by adding > `logfile /var/log/dhcpcd.log` to dhcpcd.conf. % cat /var/log/dhcpcd.log https://pastebin.com/VyJ5BXQc
> Is the DHCP server in the router? Yes, it is. It's basically a home network. (At work I use FreeBSD.) > Since I'm guessing you have a switched LAN Yes I do. > tcpdump -s 2000 -w DUMP-FILE -i wm0 It gave me a binary log. But how to read it? > ping6 -n 2001:3c8:9007:1::21 (munnari.oz.au - one of its addresses) I shall ping6 between 3:00-4:00pm GMT. But note that ping6 while it is unable, it maybe only a short term. I cannot estimate, sometimes 5 minutes or sometimes 30 minutes. After that period ping6 becomes enable without any notification. So I'm not sure whether at the time you check, it is enable or not. > I could also try a ping6 from here to your host if I know more or less > exactly what time to do it (when your host has just rebooted and things > are not working as they should). Do you mean pinging my router or my host? My host sits behind NAT. Or shall I forward the port from router to my host? (I remember when I was using 6bone, anyone can ping6 me behind LAN without port forwarding.) Anyway my host is 2405:9800:b550:2939:f234:69d6:e0bf:8ebf/64 or 2405:9800:b550:2939:8638:35ff:fe48:5720/128 and my router is 2405:9800:b550:2939:8ee1:17ff:fe1f:d1c7. > You can also look at "netstat -s" output, before, during, and after, a ping6 > that is failing, and see which numbers are growing - and let us know Before ping6, which will fail) ... # netstat -s https://pastebin.com/6K8s2QWi During ping6, which fails ... # netstat -s https://pastebin.com/AKFbrmYk During ping6, which works ... # netstat -s https://pastebin.com/kH7mc1ZB After ping6, which already worked ... # netstat -s https://pastebin.com/uvbbQDsq > So one of the changes in dhcpcd-7 was the default location of some > files, including the secret file which generates the SLAAC stable > private address. If you didn't change the location using postinstall(8) > before running dhcpcd it will have generated a new secret (and duid) > file which would result in different addresses being defined on the > interface. This could be an issue as well. It seems likely. Please tell me the old and new file locations. > You can add `nodhcp6` to dhcpcd.conf to disable DHCP6 entirely. I have done it. % tail -n 2 /etc/dhcpcd.conf logfile /var/log/dhcpcd.log nodhcp6 Now ping6 is usable even if DHCP6 is disabled entirely. > the NetBSD 7 host in question (when it was running NetBSD 7) was using > dhclient and rtsol (and kernel IPv6 addr autoconf) > Since dhcpcd was not being used previously there would have been no > old files to worry about, it would all be new. No, it was using dhcpdc and rtsol on -7. I haven't used dhclient for long, probably -5. Thank you, -- Gua Chung Lim "UNIX is basically a simple operating system, but you have to be a genius to understand the simplicity." -- Dennis M. Ritchie
