Comcast residential IPv6 works without a hiccup

With all my servers and services IPv6 enabled remotely, it was time to check out how well Comcast is doing with their residential IPv6 rollout. First thing I did was check out their listed compatible DOCSIS 3.x modems that had IPv6 support. Saw the Motorola SB6120 listed, and having used their ISDN products in mid-90s, figured it would be a good investment. Hunted around and found that the nearby Fry’s Electronics had the SB6121. Picked it up for $100. They also had Zoom modems that stated they supported IPv6. But after dealing with their Rockwell chipset modems in the early 90s, I’ll pass.

Got home, swapped out the old RCA rental from Comcast, and plugged in the new one. Called them up, got them the HFC MAC and had them provision it. Took them a bit to do, but finally my laptop was getting a Comcast IP, and that was a good start. Plugged in the D-Link DIR-825, it got its old IP back (since its MAC hadn’t changed). Went into the IPv6 WAN Configuration, and initially picked “Autoconfiguration (SLAAC/DHCPv6)”, but decided that since we live in the FUTURE, I’d let the D-Link try “Auto” and sort it out. Well it worked, and I had IPv6 on the D-Link’s WAN interface, and my laptop was autoconfiguring out of Comcast space.

But there was one last hurdle: Comcast. While IPs had configured fine, I couldn’t reach anywhere. I spent roughly 30 minutes reviewing all configuration settings, making sure I had routes, and rebooting everything a few times to no avail. Finally gave in, called back Comcast, and the tech was like “oh, let me disable the firewall on our side.” POOF! Everything worked. So Comcast residential IPv6 is definitely live in my area, and just needed a new shiny DOCSIS 3.x modem.

Tutorial: Configuring D-Link DIR-825 for Protocol 41 Tunnel

This is a quick walk-through/tutorial for configuring a Protocol 41 tunnel (from tunnelbroker.net) on a D-Link DIR-825 (rev. B) NAT appliance.

Step 1, log into your appliance and under the “Setup” tab, you’ll see a link for “IPv6”.

Step 2, after selecting “IPv6” in the setup menu, you will be presented with 2 options for configuring IPv6 on the appliance: Wizard and Manual. Select the manual configuration link.

Step 3, on this configuration menu, select “IPv6 in IPv4 Tunnel” as connection Type. Refer to your tunnel’s details page to fill in the blanks:
Server IPv4 Address = Remote IPv4 Address
Server IPv6 Address = Remote IPv6 Address
Client IPv6 Address = Local IPv6 Address
Routed /64 = LAN IPv6 Address (make certain IP ends as ::1 without the netmask)
Then save your settings and IPv6 will be made available to all your hosts connected to the DIR-825, both wired and wireless.


There still doesn’t appear to be any kind of IPv6 firewall rules to configure on the DIR-825, so make certain your hosts are secured using their own protection methods (ip6tables for Linux, Windows Firewall, etc.).