Thank you for reply Noth. It still doesn't work for me as expected. More details at the bottom.
On Thu, Jul 23, 2026 at 01:36:03AM +0200, Noth wrote: > On 22/07/2026 22:15, Mikolaj Kucharski wrote: > > > Hi. > > > > I was using for long the workaround of prefix 56 on an interface to make > > IPv6 work in OVH. I tried today to make on-link setup work, but I fail to > > figure out how, for IPv6. > > > > I'm on -current. > > > > # sysctl -n kern.version > > OpenBSD 8.0-beta (GENERIC.MP) #51: Tue Jul 21 20:50:59 MDT 2026 > > [email protected]:/usr/src/sys/arch/amd64/compile/GENERIC.MP > > > > > > Here is my hostnname.if(5): > > > > ---8<--- > > inet xxx.xxx.xxx.aaa/32 > > !route -n add -inet -host xxx.xxx.xxx.254 -link -iface \$if > > !route -n add -inet default xxx.xxx.xxx.254 > > > > inet6 zzzz:zzzz:zzz:zzdc::1 128 > > !route -n add -inet6 -host zzzz:zzzz:zzz:zzff:ff:ff:ff:ff -link -iface \$if > > !route -n add -inet6 default zzzz:zzzz:zzz:zzff:ff:ff:ff:ff > > > > up > > --->8--- > > > > Above setup for IPv4 works, but for IPv6 doesn't. Execution looks > > successful: > > > > # ifconfig ix0 -inet6 > > # sh /etc/netstart ix0 > > add host xxx.xxx.xxx.254: gateway ix0 > > add net default: gateway xxx.xxx.xxx.254 > > add host zzzz:zzzz:zzz:zzff:ff:ff:ff:ff: gateway ix0 > > add net default: gateway zzzz:zzzz:zzz:zzff:ff:ff:ff:ff > > > > but it doesn't work: > > > > # ping6 -n -c3 zzzz:zzzz:zzz:zzff:ff:ff:ff:ff > > PING zzzz:zzzz:zzz:zzff:ff:ff:ff:ff (zzzz:zzzz:zzz:zzff:ff:ff:ff:ff): 56 > > data bytes > > ping6: sendmsg: Invalid argument > > ping: wrote zzzz:zzzz:zzz:zzff:ff:ff:ff:ff 64 chars, ret=-1 > > ping6: sendmsg: Invalid argument > > ping: wrote zzzz:zzzz:zzz:zzff:ff:ff:ff:ff 64 chars, ret=-1 > > ping6: sendmsg: Invalid argument > > ping: wrote zzzz:zzzz:zzz:zzff:ff:ff:ff:ff 64 chars, ret=-1 > > > > --- zzzz:zzzz:zzz:zzff:ff:ff:ff:ff ping statistics --- > > 3 packets transmitted, 0 packets received, 100.0% packet loss > > > > > > # ndp -na | grep ff:ff > > zzzz:zzzz:zzz:zzff:ff:ff:ff:ff (incomplete) ix0 permanent > > R > > > > > > What I am missing? > > > > Please CC me with any replies as I'm not subscribed to misc. > > From man route's example: > > Add a static inet6(4) route to a host which is on the vio0 interface that is > outside your prefix, and use that host as a default gateway, as used by some > hosting providers: > > # route add -inet6 2001:db8:efef::1 -cloning -link -iface vio0 > # route add -inet6 default 2001:db8:efef::1 > Above is helpful and is a reference solution which is great. I missed this in the route(8) man page. I cannot reboot the machine at the moment, but at the same time I would expect manual IPv6 reconfiguration to just work. I am doing all of this over IPv4 configured the way as I showed earlier via hostname.if(5). I don't have IPv6 connectivity even with -cloning. See following commands: # ifconfig ix0 -inet6 # route -n delete -inet6 default delete net default: not in table # route -n delete -inet6 zzzz:zzzz:zzz:zzff:ff:ff:ff:ff delete host zzzz:zzzz:zzz:zzff:ff:ff:ff:ff: not in table # route -n show -inet6 Routing tables Internet6: Destination Gateway Flags Refs Use Mtu Prio Iface ::/96 ::1 UGRS 0 0 32768 8 lo0 ::1 ::1 UHhl 10 20 32768 1 lo0 ::ffff:0.0.0.0/96 ::1 UGRS 0 0 32768 8 lo0 2002::/24 ::1 UGRS 0 0 32768 8 lo0 2002:7f00::/24 ::1 UGRS 0 0 32768 8 lo0 2002:e000::/20 ::1 UGRS 0 0 32768 8 lo0 2002:ff00::/24 ::1 UGRS 0 0 32768 8 lo0 fe80::/10 ::1 UGRS 0 32 32768 8 lo0 fec0::/10 ::1 UGRS 0 0 32768 8 lo0 fe80::1%lo0 fe80::1%lo0 UHl 0 0 32768 1 lo0 ff01::/16 ::1 UGRS 0 16 32768 8 lo0 ff01::%lo0/32 fe80::1%lo0 Um 0 1 32768 4 lo0 ff02::/16 ::1 UGRS 0 16 32768 8 lo0 ff02::%lo0/32 fe80::1%lo0 Um 0 1 32768 4 lo0 # ndp -na Neighbor Linklayer Address Netif Expire S Flags (no other output) Based on above I assume this is a IPv6 clean start to reconfigure the network. # ifconfig ix0 inet6 zzzz:zzzz:zzz:zzdc::1/128 up # route -n add -inet6 -host zzzz:zzzz:zzz:zzff:ff:ff:ff:ff -cloning -link -iface ix0 add host zzzz:zzzz:zzz:zzff:ff:ff:ff:ff: gateway ix0 # route -n add -inet6 default zzzz:zzzz:zzz:zzff:ff:ff:ff:ff add net default: gateway zzzz:zzzz:zzz:zzff:ff:ff:ff:ff # ping6 -n -c3 zzzz:zzzz:zzz:zzff:ff:ff:ff:ff PING zzzz:zzzz:zzz:zzff:ff:ff:ff:ff (zzzz:zzzz:zzz:zzff:ff:ff:ff:ff): 56 data bytes --- zzzz:zzzz:zzz:zzff:ff:ff:ff:ff ping statistics --- 3 packets transmitted, 0 packets received, 100.0% packet loss # ping6 -n -c3 ipv6.google.com PING ipv6.l.google.com (2a00:1450:4008:802::200e): 56 data bytes --- ipv6.l.google.com ping statistics --- 3 packets transmitted, 0 packets received, 100.0% packet loss # ndp -na Neighbor Linklayer Address Netif Expire S Flags zzzz:zzzz:zzz:zzdc::1 0c:c4:7a:7b:71:0b ix0 permanent R l zzzz:zzzz:zzz:zzff:ff:ff:ff:ff 00:05:73:a0:00:01 ix0 28s R R fe80::ec4:7aff:fe7b:710b%ix0 0c:c4:7a:7b:71:0b ix0 permanent R l fe80::7270:8bff:fe3c:4d41%ix0 70:70:8b:3c:4d:41 ix0 23h53m53s S R # ndp -na Neighbor Linklayer Address Netif Expire S Flags zzzz:zzzz:zzz:zzdc::1 0c:c4:7a:7b:71:0b ix0 permanent R l zzzz:zzzz:zzz:zzff:ff:ff:ff:ff 00:05:73:a0:00:01 ix0 23h59m32s S R fe80::ec4:7aff:fe7b:710b%ix0 0c:c4:7a:7b:71:0b ix0 permanent R l fe80::7270:8bff:fe3c:4d41%ix0 70:70:8b:3c:4d:41 ix0 10s R R # ndp -na Neighbor Linklayer Address Netif Expire S Flags zzzz:zzzz:zzz:zzdc::1 0c:c4:7a:7b:71:0b ix0 permanent R l zzzz:zzzz:zzz:zzff:ff:ff:ff:ff 00:05:73:a0:00:01 ix0 23h54m38s S R fe80::ec4:7aff:fe7b:710b%ix0 0c:c4:7a:7b:71:0b ix0 permanent R l fe80::7270:8bff:fe3c:4d41%ix0 70:70:8b:3c:4d:41 ix0 23h48m3s S R # route -n show -inet6 Routing tables Internet6: Destination Gateway Flags Refs Use Mtu Prio Iface default zzzz:zzzz:zzz:zzff:ff:ff:ff:ff UGS 1 9 - 8 ix0 ::/96 ::1 UGRS 0 0 32768 8 lo0 ::1 ::1 UHhl 10 20 32768 1 lo0 ::ffff:0.0.0.0/96 ::1 UGRS 0 0 32768 8 lo0 zzzz:zzzz:zzz:zzdc::1 0c:c4:7a:7b:71:0b UHLl 0 18 - 1 ix0 zzzz:zzzz:zzz:zzff:ff:ff:ff:ff 00:05:73:a0:00:01 UHLch 1 32 - 7 ix0 zzzz:zzzz:zzz:zzff:ff:ff:ff:ff link#1 UHCS 1 0 - 8 ix0 2002::/24 ::1 UGRS 0 0 32768 8 lo0 2002:7f00::/24 ::1 UGRS 0 0 32768 8 lo0 2002:e000::/20 ::1 UGRS 0 0 32768 8 lo0 2002:ff00::/24 ::1 UGRS 0 0 32768 8 lo0 fe80::/10 ::1 UGRS 0 36 32768 8 lo0 fec0::/10 ::1 UGRS 0 0 32768 8 lo0 fe80::%ix0/64 fe80::ec4:7aff:fe7b:710b%ix0 UCn 1 2 - 4 ix0 fe80::ec4:7aff:fe7b:710b%ix0 0c:c4:7a:7b:71:0b UHLl 0 24 - 1 ix0 fe80::7270:8bff:fe3c:4d41%ix0 70:70:8b:3c:4d:41 UHLc 0 26 - 3 ix0 fe80::1%lo0 fe80::1%lo0 UHl 0 0 32768 1 lo0 ff01::/16 ::1 UGRS 0 19 32768 8 lo0 ff01::%ix0/32 fe80::ec4:7aff:fe7b:710b%ix0 Um 0 1 - 4 ix0 ff01::%lo0/32 fe80::1%lo0 Um 0 1 32768 4 lo0 ff02::/16 ::1 UGRS 0 19 32768 8 lo0 ff02::%ix0/32 fe80::ec4:7aff:fe7b:710b%ix0 Um 0 4 - 4 ix0 ff02::%lo0/32 fe80::1%lo0 Um 0 1 32768 4 lo0 Above shows that OpenBSD can see mac-address of zzzz:zzzz:zzz:zzff:ff:ff:ff:ff however I cannot ping6 typical IPv6 addresses which are pingable. I cannot reach the machine via zzzz:zzzz:zzz:zzdc::1 from another part of the Internet too. PF configuration is from the default install: # sha256 < /etc/pf.conf 479bf4f96743322aa7aa914ca0fcaa993347da9fc7bb210c87a8cd7272a3cbaf # sysctl -n kern.version OpenBSD 8.0-beta (GENERIC.MP) #51: Tue Jul 21 20:50:59 MDT 2026 [email protected]:/usr/src/sys/arch/amd64/compile/GENERIC.MP # file /etc/sysctl.conf /etc/sysctl.conf: cannot stat '/etc/sysctl.conf' (No such file or directory) I didn't manage to configure anything on this machine yet as this is fairly fresh install. Any further tips are appreciated. -- Regards, Mikolaj
