On 2026-09-21 18:37:04 +0200, Nicolas George wrote:
> Millions of people in the world use Linux with ISPs and routeurs without
> IPv6 support and they do not need to disable anything.
This does not mean that others will not have any issue either. In my
case, at home in 2017, after a power outage in the whole neighborhood,
IPv6 was no longer working with my ISP (SFR). Here's what I was getting
for a remote-to-local traceroute:
ioooi:~> mtr -brw 2a02:8429:80cd:3100::1
Start: Wed Jul 19 16:11:15 2017
HOST: ioooi
Loss% Snt Last Avg Best Wrst StDev
1.|-- 2001:4b98:dc0:45::250
0.0% 10 0.7 1.2 0.7 3.0 0.6
2.|-- p252-core4-d-ip6.paris.gandi.net (2001:4b98:1f::c4d3:181)
0.0% 10 4.0 2.5 1.3 4.0 0.7
3.|-- ???
100.0 10 0.0 0.0 0.0 0.0 0.0
4.|-- 2a02-8400-0000-0003-0000-0000-0000-421a.rev.sfr.net
(2a02:8400:0:3::421a) 0.0% 10 8.2 6.7 2.8 12.0 2.8
5.|-- 2a02-8400-0000-0003-0000-0000-0000-104d.rev.sfr.net
(2a02:8400:0:3::104d) 0.0% 10 4.1 5.7 2.7 11.9 2.4
6.|-- 2a02-8400-0000-0003-0000-0000-0000-104d.rev.sfr.net
(2a02:8400:0:3::104d) 0.0% 10 2.2 4.8 2.2 14.1 3.4
7.|-- 2a02-8400-0000-0003-0000-0000-0000-11a6.rev.sfr.net
(2a02:8400:0:3::11a6) 0.0% 10 2.5 15.4 2.0 131.4 40.8
8.|-- 2a02-8400-0000-0003-0000-0000-0000-000a.rev.sfr.net (2a02:8400:0:3::a)
0.0% 10 2.5 4.3 1.9 22.8 6.5
9.|-- 2a02-8429-80cd-bd00-0000-0000-0000-0001.rev.sfr.net
(2a02:8429:80cd:bd00::1) 0.0% 10 10.3 11.2 8.5 13.1 1.2
10.|-- ???
100.0 10 0.0 0.0 0.0 0.0 0.0
and in the opposite direction:
zira:~> mtr -6brw ioooi.vinc17.net
Start: Sat Jul 22 14:50:51 2017
HOST: zira
Loss% Snt Last Avg Best Wrst StDev
1.|-- box (2a02:8429:80cd:3100::1)
0.0% 10 0.6 0.6 0.5 0.6 0.0
2.|-- 2a02-8400-0000-0002-0000-0000-0000-08b0.rev.sfr.net
(2a02:8400:0:2::8b0) 0.0% 10 2.3 3.2 1.0 5.1 1.2
3.|-- 2a02-8400-0000-0003-0000-0000-0000-2af1.rev.sfr.net
(2a02:8400:0:3::2af1) 0.0% 10 2.5 3.9 2.3 5.9 1.2
4.|-- ???
100.0 10 0.0 0.0 0.0 0.0 0.0
SFR told me that there were no issues on their side.
This lasted several weeks.
What I did at that time was to put
precedence ::ffff:0:0/96 100
in /etc/gai.conf to prefer IPv4 connections. This was sufficient;
however, I suppose that this would not be ideal for hosts with only
an IPv6 address (timeout instead of immediate failure).
--
Vincent Lefèvre <[email protected]> - Web: <https://www.vinc17.net/>
100% accessible validated (X)HTML - Blog: <https://www.vinc17.net/blog/>
Work: CR INRIA - computer arithmetic / Pascaline project (LIP, ENS-Lyon)
