RE: kern/60323: IPv6 NDP issue since upgrade to 11.0_RC4

["Marcin Gondek via gnats" <gnats-admin%NetBSD.org@localhost>]

The following reply was made to PR kern/60323; it has been noted by GNATS.

From: Marcin Gondek <drixter%e-utp.net@localhost>
To: "gnats-bugs%netbsd.org@localhost" <gnats-bugs%netbsd.org@localhost>,
	"kern-bug-people%netbsd.org@localhost" <kern-bug-people%netbsd.org@localhost>,
	"gnats-admin%netbsd.org@localhost" <gnats-admin%netbsd.org@localhost>, "netbsd-bugs%netbsd.org@localhost"
	<netbsd-bugs%netbsd.org@localhost>
Cc: 
Subject: RE: kern/60323: IPv6 NDP issue since upgrade to 11.0_RC4
Date: Fri, 12 Jun 2026 07:52:24 +0000

 Hi
 
 I'm not using any firewall on Linux or NetBSD, it's done by HW firewall.
 
 I don't see such case, just FYI.
 
 Linux: 2001:67c:21ec:1000::c/64
 NetBSD: 2001:67c:21ec:1000:6e4b:90ff:fea3:6ec3/64
 
 Linux:
 
 inferno:~ # uname -a
 Linux inferno.e-utp.net 7.0.9-1-default #1 SMP PREEMPT_DYNAMIC Sun May 17 1=
 9:37:08 UTC 2026 (9b5964b) aarch64 aarch64 aarch64 GNU/Linux
 inferno:~ # ip -6 neigh show
 fe80::e223:ffff:fe9f:26f dev end0 lladdr e0:23:ff:9f:02:6f router REACHABLE
 2001:67c:21ec::53 dev end0 lladdr b4:96:91:29:ce:c8 STALE
 2001:67c:21ec:1000:6e4b:90ff:fea3:6ec3 dev end0 lladdr b4:96:91:29:ce:c8 ST=
 ALE
 fe80::b696:91ff:fe29:cec8 dev end0 lladdr b4:96:91:29:ce:c8 STALE
 fe80::e223:ffff:fe9f:270 dev end0 FAILED
 inferno:~ # ping -c 4 devil.e-utp.net
 PING devil.e-utp.net (2001:67c:21ec:1000:6e4b:90ff:fea3:6ec3) 56 data bytes
 64 bytes from devil.e-utp.net (2001:67c:21ec:1000:6e4b:90ff:fea3:6ec3): icm=
 p_seq=3D1 ttl=3D64 time=3D0.190 ms
 64 bytes from devil.e-utp.net (2001:67c:21ec:1000:6e4b:90ff:fea3:6ec3): icm=
 p_seq=3D2 ttl=3D64 time=3D0.233 ms
 64 bytes from devil.e-utp.net (2001:67c:21ec:1000:6e4b:90ff:fea3:6ec3): icm=
 p_seq=3D3 ttl=3D64 time=3D0.261 ms
 64 bytes from devil.e-utp.net (2001:67c:21ec:1000:6e4b:90ff:fea3:6ec3): icm=
 p_seq=3D4 ttl=3D64 time=3D0.241 ms
 
 --- devil.e-utp.net ping statistics ---
 4 packets transmitted, 4 received, 0% packet loss, time 3057ms
 rtt min/avg/max/mdev =3D 0.190/0.231/0.261/0.025 ms
 inferno:~ #
 
 NetBSD 11.0_RC4:
 [NetBSD-root@devil:~]$ uname -a
 NetBSD devil.e-utp.net 11.0_RC4 NetBSD 11.0_RC4 (DEVIL) #12: Mon May 25 20:=
 18:27 CEST 2026  root%devil.e-utp.net@localhost:/usr/obj/sys/arch/amd64/compile/DEVIL=
  amd64
 [NetBSD-root@devil:~]$ ping6 -c 4 inferno.e-utp.net
 PING6(56=3D40+8+8 bytes) 2001:67c:21ec:1000:6e4b:90ff:fea3:6ec3 --> 2001:67=
 c:21ec:1000::c
 16 bytes from 2001:67c:21ec:1000::c, icmp_seq=3D0 hlim=3D64 time=3D0.331 ms
 16 bytes from 2001:67c:21ec:1000::c, icmp_seq=3D1 hlim=3D64 time=3D0.261 ms
 16 bytes from 2001:67c:21ec:1000::c, icmp_seq=3D2 hlim=3D64 time=3D0.288 ms
 16 bytes from 2001:67c:21ec:1000::c, icmp_seq=3D3 hlim=3D64 time=3D0.278 ms
 
 --- inferno.e-utp.net ping6 statistics ---
 4 packets transmitted, 4 packets received, 0.0% packet loss
 round-trip min/avg/max/std-dev =3D 0.261/0.290/0.331/0.030 ms
 [NetBSD-root@devil:~]$ ndp -an
 Neighbor                                Linklayer Address  Netif Expire    =
 S Fl
 fe80::e65f:1ff:fe4b:ccf1%ixg0           e4:5f:01:4b:cc:f1   ixg0 20s       =
 R
 2001:67c:21ec:1000::c                   e4:5f:01:4b:cc:f1   ixg0 15s       =
 R
 fe80::e223:ffff:fe9f:26f%ixg0           e0:23:ff:9f:02:6f   ixg0 5s        =
 R R
 2001:67c:21ec:1000:219:e2ff:feec:41c0   e0:23:ff:9f:02:6f   ixg0 21s       =
 R R
 [NetBSD-root@devil:~]$
 
 Thanks,
 
 --
 Marcin Gondek / Drixter
 http://fido.e-utp.net/
 AS56662
 
 -----Original Message-----
 From: netbsd-bugs-owner%NetBSD.org@localhost <netbsd-bugs-owner%NetBSD.org@localhost> On Behalf=
  Of df4nx%gmx.net@localhost via gnats
 Sent: Friday, June 12, 2026 9:40 AM
 To: kern-bug-people%netbsd.org@localhost; gnats-admin%netbsd.org@localhost; netbsd-bugs@netbsd.=
 org
 Subject: kern/60323: IPv6 NDP issue since upgrade to 11.0_RC4
 
 >Number:         60323
 >Category:       kern
 >Synopsis:       Neighbor Discovery Protocol on 11.0_RC4
 >Confidential:   no
 >Severity:       non-critical
 >Priority:       low
 >Responsible:    kern-bug-people
 >State:          open
 >Class:          sw-bug
 >Submitter-Id:   net
 >Arrival-Date:   Fri Jun 12 07:40:00 +0000 2026
 >Originator:     =3D09
 >Release:        NetBSD 11.0_RC4
 >Organization:
 	home user
 >Environment:
 =3D09
 =3D09
 System: NetBSD at166.local 11.0_RC4 NetBSD 11.0_RC4 (GENERIC) #0: Tue May =
 =3D
 12 04:23:51 UTC 2026 mkrepro%mkrepro.NetBSD.org@localhost:/usr/src/sys/arch/amd64/co=
 =3D
 mpile/GENERIC amd64
 Architecture: x86_64
 Machine: amd64
 >Description:
 	The host runs IPv6 with a static assigned IPv6 address. Trying
 	to ping6 this address from a Linux host on the LAN failes.
 	ping6 from a other NetBSD or OpenBSD host on the same LAN works.
 	Ping6 and connect from the internet to the static IPv6 address
 	works. `tcpdump icmp6` on the Linux host on the same LAN shows
 	outgoing NDP Packets, but no incoming answer.
 	The problem did not occur on NetBSD 10.1.
 	For test purposes I have switched off NPF, but this did not fix
 	the issue.
 	It looks like a problem with the Neighbor Discovery Protocol on
 	11.0_RC4.
 	To double check I have two other hosts without static IPv6
 	address. One 10.1, the other 11.0_RC4. The 10.1 host can be
 	pinged, the 11.0_RC4 not. I used the dynnamic assigned IPv6
 	address. None of these two systems run NPF.
 	See also this blogpost:
 	https://sirius-a.neocities.org/#v6issue
 >How-To-Repeat:
 	I used a installed Debian 13.5, a Debian live system (13.5 XFCE)
 	and a Fedora Live 44-1.7 to test on the LAN.
 	Ping6 and connect from the internet with:
 	https://www.ipv6tech.ch/?pingv4v6
 	https://www.ipv6tech.ch/?tcpportscan
 	Tests with OpenBSD are done with the FuguIta live system:
 	https://fuguita.org/
 >Fix:
 	Work around: Running the following command on the Linux host
 	(Debian 13.5) works:
 	ip -6 neigh replace XXXX:XXXX:XXXX:XXXX::1 lladdr yy:yy:yy:yy:yy:yy dev e=
 =3D
 no1
 	with XXXX is my /64 prefix and yy is my MAC.
 
 >Unformatted:
  =3D09
  =3D09