1

I have an usb ethernet adapter that I use to test network configuration, a Raspberry pi is at the other end of the cable.

I'm trying to setup ipv6 connectivity, but a link-local address is never set. On my local machine:

$ ip -br a
ip a
enxa0cec855bd4d  DOWN 
$ sudo ip -6 addr add "fc00:7500:6700::1/64" dev enxa0cec855bd4d 
$ ip a
enxa0cec855bd4d  DOWN           fc00:7500:6700::1/64 
# Power up raspberry so iface comes up
$ ip a
enxa0cec855bd4d  UP             fc00:7500:6700::1/64

There is no fe80:: address :(, let's try will the iface is up from the beginning:

$ ip -br a
ip a
enxa0cec855bd4d  UP 
$ sudo ip -6 addr add "fc00:7500:6700::1/64" dev enxa0cec855bd4d 
$ ip a
enxa0cec855bd4d  UP           fc00:7500:6700::1/64

There is no link-local address.

My main internet iface correctly gets an ipv6 link-local and global addr, I have the following sysctl

net.ipv6.conf.enxa0cec855bd4d.accept_dad = 1
net.ipv6.conf.enxa0cec855bd4d.accept_ra = 0
net.ipv6.conf.enxa0cec855bd4d.addr_gen_mode = 1
net.ipv6.conf.enxa0cec855bd4d.autoconf = 1
net.ipv6.conf.enxa0cec855bd4d.disable_ipv6 = 0

Why this iface not getting a link-local addr?

Improve this question
2
  • Was there no link-local address when you initially connected the adapter? If I remember correctly, one is added when the interface is created, not every time it's brought up.
    – grawity_u1686
    Commented Apr 9, 2022 at 16:12
  • I just tried, even if the raspberry network interface is up before I plug in the usb adapter, no ipv6 (or ipv4) appears
    – izissise
    Commented Apr 9, 2022 at 18:16

2 Answers 2

Reset to default
2

I found that my RPI had addr_gen_mode set to 1, and I was not running network-manager, so nothing setup the address. I restored it to 0 in sysctl.conf, and it worked. This article helped me understand this: https://medium.com/opsops/how-to-restore-link-local-ipv6-address-in-linux-737666a505f3

sysctl -w net.ipv6.conf.eth0.addr_gen_mode=0
Improve this answer
3
  • If this answers your question please accept it so the community is aware.
    – Blindspots
    Commented Jul 31, 2023 at 19:29
  • Link only answers get deleted. Please add the essential steps here.
    – Rohit Gupta
    Commented Jul 31, 2023 at 20:41
  • This is probably the solution to the problem
    – izissise
    Commented Aug 3, 2023 at 13:26
-1

After multiples tries and fails, I have been able to fix this issue by issuing the two following commands:

sudo ip -6 addr flush dev enxa0cec855bd4d scope link
sudo ip -6 link set enxa0cec855bd4d up

It works even when the iface is down, a link-local address will be correctly assigned when it comes up.

Improve this answer

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .