Tuesday November 12th, 2024 NCLUG Meeting

Bob Proulx bob at proulx.com
Sun Nov 17 22:52:32 UTC 2024


Stephen Warren wrote:
> Bob Proulx wrote:
> If you do the same experiment on both systems, so you know the working IPv6
> on both ends, can you then communicate across the local network? I.e. test
> all 6^2 combinations of IP on queasy and George's system..

It's in a strange mode today.  Ping is pretty much univerally not
working.  But TCP is working.

If I ssh from the test system into my Linode and look to see what
address was used then I can follow that address back with TCP.  But
not ping.

    rwp at rainy:~$ env | grep SSH_C
    SSH_CONNECTION=2605:b40:1516:a200:1b01:7749:55f4:1ff3 41706 2600:3c00::f03c:91ff:fe18:62e4 22
    SSH_CLIENT=2605:b40:1516:a200:1b01:7749:55f4:1ff3 41706 22
    rwp at rainy:~$ ping 2605:b40:1516:a200:1b01:7749:55f4:1ff3
    PING 2605:b40:1516:a200:1b01:7749:55f4:1ff3(2605:b40:1516:a200:1b01:7749:55f4:1ff3) 56 data bytes
    ^C
    --- 2605:b40:1516:a200:1b01:7749:55f4:1ff3 ping statistics ---
    3 packets transmitted, 0 received, 100% packet loss, time 2034ms

    rwp at rainy:~$ nc 2605:b40:1516:a200:1b01:7749:55f4:1ff3 22
    SSH-2.0-OpenSSH_9.6p1 Ubuntu-3ubuntu13.5
    ^C

So I am not sure that counts as working today.  Since ping is not
pinging.  I am thinking I might have to reboot all again and then see
if ping works.  It did before.

As to your question it is the same from George's today.

    root at yukiko# ping 2605:b40:1516:a200:1b01:7749:55f4:1ff3
    PING 2605:b40:1516:a200:1b01:7749:55f4:1ff3(2605:b40:1516:a200:1b01:7749:55f4:1ff3) 56 data bytes
    ^C
    --- 2605:b40:1516:a200:1b01:7749:55f4:1ff3 ping statistics ---
    119 packets transmitted, 0 received, 100% packet loss, time 120807ms

    root at yukiko# nc 2605:b40:1516:a200:1b01:7749:55f4:1ff3 22
    SSH-2.0-OpenSSH_9.6p1 Ubuntu-3ubuntu13.5
    ^C

No ping but TCP works.

And now for an additional oddity.  It's up to 14 IPv6 addresses now.

    root at queasy:~# ip -6 addr show eth0
    2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP group default qlen 1000
        altname enp1s0
        inet6 2605:b40:1516:a200:1b01:7749:55f4:1ff3/64 scope global temporary dynamic
           valid_lft 43078sec preferred_lft 43078sec
        inet6 2605:b40:13a3:8c00:4299:f7b7:be1d:a4fc/64 scope global temporary dynamic
           valid_lft 43078sec preferred_lft 43078sec
        inet6 2605:b40:13a3:8c00:349:8131:6d71:9c04/64 scope global temporary deprecated dynamic
           valid_lft 43078sec preferred_lft 0sec
        inet6 2605:b40:1516:a200:ef96:652f:204:a7f8/64 scope global temporary deprecated dynamic
           valid_lft 43078sec preferred_lft 0sec
        inet6 2605:b40:1516:a200:a602:10c:eab3:ba40/64 scope global temporary deprecated dynamic
           valid_lft 43078sec preferred_lft 0sec
        inet6 2605:b40:13a3:8c00:4c1a:74ab:8e5b:d99d/64 scope global temporary deprecated dynamic
           valid_lft 43078sec preferred_lft 0sec
        inet6 2605:b40:1516:a200:b12c:d96c:9307:217f/64 scope global temporary deprecated dynamic
           valid_lft 43078sec preferred_lft 0sec
        inet6 2605:b40:13a3:8c00:f08e:405b:7256:f19b/64 scope global temporary deprecated dynamic
           valid_lft 43078sec preferred_lft 0sec
        inet6 2605:b40:13a3:8c00:b978:210b:51bd:e23f/64 scope global temporary deprecated dynamic
           valid_lft 43078sec preferred_lft 0sec
        inet6 2605:b40:1516:a200:87db:ba30:b265:3c86/64 scope global temporary deprecated dynamic
           valid_lft 43078sec preferred_lft 0sec
        inet6 2605:b40:1516:a200:928d:8523:a296:f80b/64 scope global temporary deprecated dynamic
           valid_lft 43078sec preferred_lft 0sec
        inet6 2605:b40:1516:a200:37cb:35cf:cdec:71fe/64 scope global dynamic mngtmpaddr noprefixroute
           valid_lft 43078sec preferred_lft 43078sec
        inet6 2605:b40:13a3:8c00:fde7:1fca:2876:5419/64 scope global temporary deprecated dynamic
           valid_lft 43078sec preferred_lft 0sec
        inet6 2605:b40:13a3:8c00:6f33:ffb3:f4f6:9c7b/64 scope global dynamic mngtmpaddr noprefixroute
           valid_lft 43078sec preferred_lft 43078sec
        inet6 fe80::4425:2931:5fcd:845/64 scope link noprefixroute
           valid_lft forever preferred_lft forever

It's in the working state now with a :a200 prefix up top.  But if I
catch it at a different time with a :8c00 prefix up top then of course
it does not work.  I think there is a rogue router advertisement
happening.  That might be attributing to the growing list of
addresses in that it is flipflopping on prefixes.

The address is contantly changing.  That's probably an anti-tracking
security feature.  It's a dynamic assignment so that's okay.  It's
probably stacking up addresses to accomodate long running connections
which need to keep those alive.  As far as I can tell there are no
long running connections and the kernel should know this exactly.

Bob


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