[knot-dns-users] IP source on IPv6

Alarig Le Lay alarig at swordarmor.fr
Fri Jan 22 23:48:08 CET 2016


I’ve installed knot 2.0.2 on one of my server.
It’s configured with three IPv6 and I manage their reliability with some
source-specifi routing:
alarig at bulbizarre ~ $ ip -6 route list | grep default
default from 2001:470:1f13:138:715d:2fa0:b591:532f via fe80::20d:b9ff:fe3a:1fa1 dev eth0  metric 1024 
default from 2a00:5881:4008:400::1 dev tun0  metric 1024
default from 2a01:240:fe00:82af:764f:b47e:d131:85e4 via fe80::20d:b9ff:fe3a:1fa1 dev eth0  metric 1024
default via fe80::20d:b9ff:fe3a:1fa1 dev eth0  metric 4 

It works fine as I can ping those three IP from the same machine at the
same moment.

But, knot don’t take care of this and answer with the “nearest” IPv6
(like the IP source is calculated when you have several ones).
bulbizarre ~ # tcpdump -i any host mc.swordarmor.fr
23:13:07.276493 IP6 2001:41d0:a:27e4::1.52203 > florizarre.swordarmor.fr.domain: 59831+ SOA? swordarmor.fr. (31)
23:13:07.276647 IP6 bulbizarre.swordarmor.fr.domain > 2001:41d0:a:27e4::1.52203: 59831*- 1/0/0 SOA (86)
You can see that knot answer with 2001:470:1f13:138:715d:2fa0:b591:532f, which
is the one chosen if I’m the initiator of the connection.

Indeed, it works with my IRCd:
23:14:17.684155 IP6 2001:41d0:a:27e4::1.36490 > florizarre.swordarmor.fr.6697: Flags [P.], seq 53:106, ack 106, win 331, options [nop,nop,TS val 4047617704 ecr 1587664633], length 53
23:14:17.684301 IP6 florizarre.swordarmor.fr.6697 > 2001:41d0:a:27e4::1.36490: Flags [P.], seq 106:211, ack 106, win 240, options [nop,nop,TS val 1587724598 ecr 4047617704], length 105
23:14:22.555891 IP6 2001:41d0:a:27e4::1.34822 > bulbizarre.swordarmor.fr.6697: Flags [P.], seq 1:62, ack 61, win 331, options [nop,nop,TS val 4047618922 ecr 1587729432], length 61
23:14:22.555928 IP6 bulbizarre.swordarmor.fr.6697 > 2001:41d0:a:27e4::1.34822: Flags [.], ack 62, win 274, options [nop,nop,TS val 1587729469 ecr 4047618922], length 0

Is it a known bug?

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