Re: kern/52554: IPv6 connections not routing to default gateway

[Roy Bixler <rcbixler%nyx.net@localhost>]

The following reply was made to PR kern/52554; it has been noted by GNATS.

From: Roy Bixler <rcbixler%nyx.net@localhost>
To: gnats-bugs%NetBSD.org@localhost
Cc: ozaki-r%NetBSD.org@localhost, gnats-admin%netbsd.org@localhost, netbsd-bugs%netbsd.org@localhost
Subject: Re: kern/52554: IPv6 connections not routing to default gateway
Date: Fri, 29 Sep 2017 07:56:13 -0600

 On Thu, Sep 28, 2017 at 09:55:01PM +0000, Ryota Ozaki wrote:
 >  Oh sorry, I suppose to see packets of telnet by tcpdump on br0 and eth0
 >  of Linux. I suspected that a SYN packet is broken and filtered out on the
 >  interfaces for some reasons. And also we may see a SYNACK packet on
 >  the interfaces if a SYN packet reaches the server.
 
 I wasn't thinking the same way, since I have had success with IPv6 on
 guests running different operating systems, like NetBSD 7.1.  I also
 have success with IPv6 on NetBSD 8 when connecting to other hosts on
 the same LAN.  That only changes when I try to connect outside the
 LAN.
 
 I decided to try something different, which is an "ssh" connection
 with IPv6 to a host outside of the LAN.  I run tcpdump locally and on
 the remote host.  What appears to happen is that the NetBSD 8 host
 sends its SYN packets, the remote host receives them and tries to
 reply, but NetBSD 8 never sees the replies.
 
 Here's the trace from NetBSD 8 (times in UTC):
 
 13:27:00.789450 IP6 2620:105:c000:3:58a4:a8c:71ce:44f9.65532 >
 2620:105:c002:2:5054:ff:feaa:dbd1.ssh: Flags [S], seq 4071621244, win
 32768, options [mss 1440,nop,wscale 3,sackOK,TS val 1 ecr 0], length 0
 13:27:06.788199 IP6 2620:105:c000:3:58a4:a8c:71ce:44f9.65532 >
 2620:105:c002:2:5054:ff:feaa:dbd1.ssh: Flags [S], seq 4071621244, win
 32768, options [mss 1440,nop,wscale 3,sackOK,TS val 13 ecr 0], length
 0
 13:27:18.794959 IP6 2620:105:c000:3:58a4:a8c:71ce:44f9.65532 >
 2620:105:c002:2:5054:ff:feaa:dbd1.ssh: Flags [S], seq 4071621244, win
 32768, options [mss 1440,nop,wscale 3,sackOK,TS val 37 ecr 0], length
 0
 13:27:42.808871 IP6 2620:105:c000:3:58a4:a8c:71ce:44f9.65532 >
 2620:105:c002:2:5054:ff:feaa:dbd1.ssh: Flags [S], seq 4071621244, win
 32768, options [mss 1440,nop,wscale 3,sackOK,TS val 85 ecr 0], length
 0
 
 and from the remote host (times local ~ 4 sec. fast):
 
 08:27:04.693607 IP6 2620:105:c000:3:58a4:a8c:71ce:44f9.65532 >
 2620:105:c002:2:5054:ff:feaa:dbd1.ssh: Flags [S], seq 4071621244, win
 32768, options [mss 1440,nop,wscale 3,sackOK,TS val 1 ecr 0], length 0
 08:27:04.693706 IP6 2620:105:c002:2:5054:ff:feaa:dbd1.ssh >
 2620:105:c000:3:58a4:a8c:71ce:44f9.65532: Flags [S.], seq 3269583768,
 ack 4071621245, win 28560, options [mss 1440,sackOK,TS val 577917728
 ecr 1,nop,wscale 7], length 0
 08:27:05.692834 IP6 2620:105:c002:2:5054:ff:feaa:dbd1.ssh >
 2620:105:c000:3:58a4:a8c:71ce:44f9.65532: Flags [S.], seq 3269583768,
 ack 4071621245, win 28560, options [mss 1440,sackOK,TS val 577918728
 ecr 1,nop,wscale 7], length 0
 08:27:07.692864 IP6 2620:105:c002:2:5054:ff:feaa:dbd1.ssh >
 2620:105:c000:3:58a4:a8c:71ce:44f9.65532: Flags [S.], seq 3269583768,
 ack 4071621245, win 28560, options [mss 1440,sackOK,TS val 577920728
 ecr 1,nop,wscale 7], length 0
 08:27:10.692697 IP6 2620:105:c000:3:58a4:a8c:71ce:44f9.65532 >
 2620:105:c002:2:5054:ff:feaa:dbd1.ssh: Flags [S], seq 4071621244, win
 32768, options [mss 1440,nop,wscale 3,sackOK,TS val 13 ecr 0], length
 0
 08:27:10.692760 IP6 2620:105:c002:2:5054:ff:feaa:dbd1.ssh >
 2620:105:c000:3:58a4:a8c:71ce:44f9.65532: Flags [S.], seq 3269583768,
 ack 4071621245, win 28560, options [mss 1440,sackOK,TS val 577923727
 ecr 1,nop,wscale 7], length 0
 08:27:14.692847 IP6 2620:105:c002:2:5054:ff:feaa:dbd1.ssh >
 2620:105:c000:3:58a4:a8c:71ce:44f9.65532: Flags [S.], seq 3269583768,
 ack 4071621245, win 28560, options [mss 1440,sackOK,TS val 577927728
 ecr 1,nop,wscale 7], length 0
 08:27:22.692861 IP6 2620:105:c002:2:5054:ff:feaa:dbd1.ssh >
 2620:105:c000:3:58a4:a8c:71ce:44f9.65532: Flags [S.], seq 3269583768,
 ack 4071621245, win 28560, options [mss 1440,sackOK,TS val 577935728
 ecr 1,nop,wscale 7], length 0
 08:27:22.700595 IP6 2620:105:c000:3:58a4:a8c:71ce:44f9.65532 >
 2620:105:c002:2:5054:ff:feaa:dbd1.ssh: Flags [S], seq 4071621244, win
 32768, options [mss 1440,nop,wscale 3,sackOK,TS val 37 ecr 0], length
 0
 08:27:22.700638 IP6 2620:105:c002:2:5054:ff:feaa:dbd1.ssh >
 2620:105:c000:3:58a4:a8c:71ce:44f9.65532: Flags [S.], seq 3269583768,
 ack 4071621245, win 28560, options [mss 1440,sackOK,TS val 577935735
 ecr 1,nop,wscale 7], length 0
 08:27:38.699848 IP6 2620:105:c002:2:5054:ff:feaa:dbd1.ssh >
 2620:105:c000:3:58a4:a8c:71ce:44f9.65532: Flags [S.], seq 3269583768,
 ack 4071621245, win 28560, options [mss 1440,sackOK,TS val 577951735
 ecr 1,nop,wscale 7], length 0
 08:27:46.716395 IP6 2620:105:c000:3:58a4:a8c:71ce:44f9.65532 >
 2620:105:c002:2:5054:ff:feaa:dbd1.ssh: Flags [S], seq 4071621244, win
 32768, options [mss 1440,nop,wscale 3,sackOK,TS val 85 ecr 0], length
 0
 08:27:46.716437 IP6 2620:105:c002:2:5054:ff:feaa:dbd1.ssh >
 2620:105:c000:3:58a4:a8c:71ce:44f9.65532: Flags [S.], seq 3269583768,
 ack 4071621245, win 28560, options [mss 1440,sackOK,TS val 577959751
 ecr 1,nop,wscale 7], length 0
 
 
 -- 
 Roy Bixler <rcbixler%nyx.net@localhost>
 "The fundamental principle of science, the definition almost, is this: the
 sole test of the validity of any idea is experiment."
 -- Richard P. Feynman