[FS#73] Router doesn't answer to ping to ff02::1

[LEDE Bugs]

A new Flyspray task has been opened.  Details are below. 

User who did this - Juliusz Chroboczek (jch) 

Attached to Project - LEDE Project
Summary - Router doesn't answer to ping to ff02::1
Task Type - Bug Report
Category - Base system
Status - Unconfirmed
Assigned To - 
Operating System - All
Severity - Low
Priority - Very Low
Reported Version - Trunk
Due in Version - Undecided
Due Date - Undecided
Details - At some point, OpenWRT (and then LEDE) stopped answering to pings to the link-local multicast group:

    $ ping6 -c1 ff02::1%wlan0
    PING ff02::1%wlan0(ff02::1%wlan0) 56 data bytes
    64 bytes from fe80::9677:bc3a:332e:428d%wlan0: icmp_seq=1 ttl=64 time=0.095 ms
    
    --- ff02::1%wlan0 ping statistics ---
    1 packets transmitted, 1 received, 0% packet loss, time 0ms
    rtt min/avg/max/mdev = 0.095/0.095/0.095/0.000 ms

The reply here is spurious -- it comes from my local host.

On the other hand, I can access the router over it's link-local unicast address:

    $ ping6 -c1 fe80::e246:9aff:fe4e:9176%wlan0
    PING fe80::e246:9aff:fe4e:9176%wlan0(fe80::e246:9aff:fe4e:9176%wlan0) 56 data bytes
    64 bytes from fe80::e246:9aff:fe4e:9176%wlan0: icmp_seq=1 ttl=64 time=10.0 ms
    
    --- fe80::e246:9aff:fe4e:9176%wlan0 ping statistics ---
    1 packets transmitted, 1 received, 0% packet loss, time 0ms
    rtt min/avg/max/mdev = 10.020/10.020/10.020/0.000 ms

This is particularly inconvenient when you've mis-configured the router so that it no longer has an IPv4 address on any interface.



More information can be found at the following URL:
https://bugs.lede-project.org/index.php?do=details&task_id=73