dhcpcd-discuss

Hi

On 16/02/2021 02:40, Antonino Sidoti wrote:
> My first time on this list. I’m using dhcpcd on OpenBSD 6.8. It has two 
> interfaces named em0 (WAN) and em1 (LAN). My provider is an Australian Telco and 
> they have for about a year enabled IPv6 on their network. The link is a 4G 
> Mobile Broadband network. My 4G modem is configured in Bridge mode , therefore 
> my OpenBSD firewall has the public IP and it is a dual stack too. Being a 4G 
> network my telco is only handing out /64 addresses.
>
> Using dhcpcd I am unable to get an IPv6 address on em1 interface. It wants to 
> add the IPv6 address to the em0 interface which I think I not the correct 
> interface. Could someone please check the dhcpcd.conf listed below and confirm 
> if I have the correct settings. Also I have provided output of my interfaces 
> showing the IPv6 address on em0 interface. More information about the version of 
> dhcpcd is listed too.
>
> If more information is required then please let me know?
>
> ifconfig
> lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> mtu 32768
>          index 4 priority 0 llprio 3
>          groups: lo
>          inet6 ::1 prefixlen 128
>          inet6 fe80::1%lo0 prefixlen 64 scopeid 0x4
>          inet 127.0.0.1 netmask 0xff000000
> em0: flags=808843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST,AUTOCONF4> mtu 1500
>          lladdr 00:e0:67:15:e7:82
>          index 1 priority 0 llprio 3
>          groups: egress
>          media: Ethernet autoselect (1000baseT full-duplex,master,rxpause,txpause)
>          status: active
>          inet 22.230.33.40 netmask 0xffffff00 broadcast 22.230.33.255
>          inet6 fe80::2e0:67ff:fe15:e782%em0 prefixlen 64 scopeid 0x1
>          inet6 2001:8004:1480:45c9:2e0:67ff:fe15:e782 prefixlen 64 autoconf

So em0 is connected to your WAN.
It has an IPv6 autoconf address, which matches how you describe your telco 
handing out /64

> em1: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
>          lladdr 00:e0:67:15:e7:83
>          index 2 priority 0 llprio 3
>          media: Ethernet autoselect (1000baseT full-duplex,rxpause,txpause)
>          status: active
>          inet 10.99.1.1 netmask 0xffffff00 broadcast 10.99.1.255
>          inet6 fe80::2e0:67ff:fe15:e783%em1 prefixlen 64 scopeid 0x2
> enc0: flags=0<>
>          index 3 priority 0 llprio 3
>          groups: enc
>          status: active
> pflog0: flags=141<UP,RUNNING,PROMISC> mtu 33136
>          index 5 priority 0 llprio 3
>          groups: pflog
>
> dhcpcd.conf
> logfile /var/log/dhcpcd.log
> ipv6only
> noipv6rs
> duid
> persistent
> option rapid_commit
> require dhcp_server_identifier
>
> script ""
>
> allowinterfaces em0 em1
>
> interface em0
>    ipv6rs
>    ia_pd 1/::/64 em1/0/64
>
> dhcpcd 9.3.1
> Copyright (c) 2006-2020 Roy Marples
> Compiled in features: INET ARP ARPing IPv4LL INET6 DHCPv6 AUTH PRIVSEP

Nothing wrong here.
To me it looks like you only get a /64 via SLAAC and your ISP does not provision 
any more via Prefix Delegation.
If you add the debug directive you may get more detail in the DHCP6 transaction 
if any.

Technically you can split this /64 into a /68 and the allocate to your LAN via 
DHCP6. However as a /68 it means SLAAC won't work in your LAN as that does 
require a /64 - and this stops android devices as they don't support DHCP6 at 
all. Sucks for android.

Roy