Author Topic: L2TP and IPv6 tunnel shenanigans  (Read 251 times)

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Offline steve30

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L2TP and IPv6 tunnel shenanigans
« on: January 12, 2020, 12:27:39 am »
I've been playing with L2TP tunnels and IPv6 lately and seem to be digging myself into a deeper hole.

I took out Andrews & Arnold's L2TP service to get myself a fixed IP address (and a block of IPv6 addresses), because I don't have my own internet connection - I tend to use other people's wireless networks to get internet access, with various levels of NAT and no native IPv6. See https://www.aa.net.uk/broadband/l2tp-service/

I have a Draytek 2926n router which I thought would work, but seems a bit peculiar. It will do the L2TP connection to Andrews & Arnold and get an IPv4 address, but it will not get an IPv6 address through DHCPv6, which it is supposed to.

Alternatively, you can configure A&A to do your IPv6 as a 6in4 tunnel, which the Draytek also 'supports', but again, this doesn't work in the L2TP mode. I have a feeling that the Draytek isn't actually trying to get the IPv6 over the L2TP connection at all, and is trying to get it through the underlying WAN connection.

I also have a Linksys WRT54G running Tomato. If I have this do the L2TP connection, then hook the Draytek up to it and have the Draytek do the 6in4 tunnel, it works fine.

Unfortunately my Tomato router doesn't do IPv6 and I don't have anything else which does (other than the Draytek).

Am I asking too much to expect IPv6 connectivity over an L2TP connection? Or is this a rather poor limitation of Draytek routers?

I've attached some screenshots of the Draytek config page showing how the IPv6 tunnel works when the L2TP is done in another machine, and how it doesn't work when the Draytek itself does the L2TP.

Edit: NetworkManager in Linux will do the L2TP connection, but won't get any IPv6. pfSense will also do the L2TP connection but also doesn't seem to get any IPv6.  :-//

I'd appreciate any suggestions for solutions or workarounds, or suggestions for hardware that might accomplish all this in one box.

Thanks
steve30 :)
« Last Edit: January 19, 2020, 04:39:52 pm by steve30 »
 


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