#6803 fedorapeople.org IPv6 acts strangely
Closed: Fixed 2 years ago Opened 2 years ago by rjones.

Symtom is that ssh logins hang randomly. It turns out this is because IPv6 is acting up.

From some machines I see !X errors:

# traceroute6 2610:28:3090:3001:5054:ff:fea7:9474
...
20  2610:28:3090:3001:5054:ff:fea7:9474 (2610:28:3090:3001:5054:ff:fea7:9474)  92.164 ms !X  92.878 ms !X  93.690 ms !X

From others it never reaches the destination at all.


Thanks for reporting this

Something is going on with ipv6 in the 'area'. Both my home ipv6 and the ipv6 at UNC are giving unreachable for various routers that are seen in ipv4.

OK circling back.. !X errors are expected and you get them for both ipv4 and ipv6 addresses against any Fedora Project host . From the man page '!X (communication administratively prohibited)' which comes about from the fall through iptables rule:

-A INPUT -j REJECT --reject-with icmp-host-prohibited

It can also happen if any host in between you and us didn't allow the random dest UDP packets. So if you are seeing a !X at the end, it is probably good. When it doesn't connect at all that is a different matter and is where the ipv6 network is no longer peering somewhere on the route which still seems to happen a lot. [We see this fairly regularly from various ipv6 hosts in fedora not able to see some other set.]

Metadata Update from @smooge:
- Issue assigned to smooge

2 years ago

Is this still happening? Or was it a transient issue?

Right now it's working.

OK, I am closing as fixed.. only because there is no "who knows" resolution :wine_glass:

Metadata Update from @smooge:
- Issue close_status updated to: Fixed

2 years ago

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