Just tried to update the ipv4 endpoint of my tunnel (pop: ams) via the web interface, and it didn't work; instead, it shows an error message claiming that the "IPv4 endpoint is unreachable or unstable" and the instruction that "Your IPv4 endpoint must be pingable. If you are blocking ICMP, please allow ipv6.he.net through your firewall".
Tcpdump however reveals that the ping requests do not originate from ipv6.he.net/64.62.200.2 but from arc.he.net/66.220.2.74:
Quote12:28:28.430646 IP (tos 0x0, ttl 56, id 0, offset 0, flags [DF], proto ICMP (1), length 84) 66.220.2.74 > [ipv4 endpoint of tunnel]: ICMP echo request, id 2611, seq 1, length 64
Ah, thanks for the reminder. Obviously we forgot to update that when we consolidated the servers. I'll get that changed now.
(EDIT) I've changed it to have the IP address that should be allowed.