IPv6 global address lost after delay

2

I have a (gentoo linux) computer behind a home router (Fritz!Box 7360). When I initially connect it via a wired connection, it is assigned a link-local address (fe80:...), a unique local address (fd00:...) and a global address (2001:...). After some time I'm only left with the link-local address, however as soon as I use the computer to access an external site (e.g. ping google.com), all of the addresses are restored.

I want to be able to SSH to this computer, and for that I need the global address to stay valid. Is it possible to configure this, and if so where do I need to do so?

The router is set to only advertise a DNS server via DHCP, I don't know what other information is relevant so please comment if I've missed something important.

kai

Posted 2015-04-24T11:28:06.507

Reputation: 191

This sounds quite obscure. I have no idea how to approach this other than inspecting a packet trace between computer and router while the computer get an IP, lose it, and get it again. Something along the lines of tcpdump -pni eth0 -s0 -Uw output.pcap and then with that running wait for the computer to lose the IP and ping an external site to get it again, and repeat one more time before stopping tcpdump. – kasperd – 2015-04-25T08:06:23.497

Check your system logs for any problems. – Michael Hampton – 2015-04-25T19:10:08.327

Answers

1

I experienced something similar, but I can't tell you if this applies to you.

I had a wireless Access Point hooked up in my LAN that acted as a simple bridge. It did not support IPv6. However... it somehow managed to 'reflect' IPv6 packets back into the network with a different MAC address. So my PC would see packets coming in with its own IPv6 address but a different MAC address and declared itself a duplicate. Turning off DAD (Duplicate Address Detection) on my system helped, but it had to be enabled on all systems in order to get it working. In the end ditching the access point was the easy solution. You may have a similar non-compliant device in your network.

JvO

Posted 2015-04-24T11:28:06.507

Reputation: 883

Asked: 2015-04-24T11:28:06.507

Viewed: 651 times

Active: 2015-08-19T18:27:27.467