Tag: internode

Years ago, I posted about how to get IPv6 routing working with PPP connections and Debian buster. Since then, the systemd-networkd configuration schema has changed significantly. Here are updated instructions for how I set up my router with Debian 13 (trixie), using systemd v257.

Here’s what I’ve configured the router to do to establish an internet connection:

• Create a PPPoE (ppp0) connection to the internet. My ISP, Internode, requires a 802.1q VLAN to be set on the ethernet frames, so in my case this will be over eth1.2.
• Establish its internet IPv4 address via PPP/IPCP.
• Solicit an IPv6 prefix via DHCPv6.

And in terms of providing routing for my LAN:

• Respond to DHCPv4 requests, setting itself as the gateway, and assigning IPv4 addresses on the LAN.
• Respond to IPv6 router solicitation requests, advertising the IPv6 prefix and SLAAC.
• NAT for IPv4.
• Packet forwarding for IPv6.

All of this can be achieved with systemd-networkd and pppd, without the need for any other DHCP client/server software, or NetworkManager.

Continue reading “Linux IPv6 NBN routing with systemd-networkd: update”

Update: See the new instructions for Debian 13 (trixie) / systemd v257.

Internode’s instructions for configuring IPv6 routing on linux are pretty terse, merely giving some suggestions for using WIDE DHCPv6 and radvd. On modern Linux with systemd, these extra daemons are unnecessary; all that’s required is systemd-networkd. This post describes the problems and how I got dual-stack IPv4/IPv6 routing over Internode’s NBN service, using a Raspberry Pi running Debian Buster.

Firstly, here’s all the things we want the router to do:

• Create a PPPoE connection to Internode via the NBN (HFC).
• Establish the IPv6 address of the upstream router and create a default route there.
• Issue Router Advertisements (RA) to other hosts on the LAN so that they can configure their global IPv6 address and default route using SLAAC.
• Act as a DHCPv6 client for Prefix Delegation. It’s not obvious why this is required: Internode allocates a static /56 prefix, and I can statically configure my router to advertise that in its RA. However, it turns out that without the DHCP lease, upstream routes aren’t created for hosts in the /56 prefix!

Glen Turner has an excellent guide for a setup on Debian Wheezy consistent with Internode’s recommendation, using the radvd and wide-dhcpv6-client packages. But on Debian Buster, this feels quite outdated: wide-dhcp6cd will exit immediately (rather than wait) if its config mentions an interface that doesn’t exist. Hence systemd disables it because of the fail-loop it enters on system boot when ppp0 doesn’t exist. On top of this, there’s no good logging level for wide-dhcp6cd; the “debug” level pours out minutiae of config-file parsing, while the merely “verbose” level gives no indication about what the DHCP replies contain. It’s also using a SysV-style init script rather than a modern systemd service.

I’ve also avoided using GNOME’s NetworkManager, which I feel is too bloated for a headless router in a stable network topology.

My configs follow.

Continue reading “Internode IPv6 on Linux with systemd-networkd”