I'm using NeptuneOS 6.5 on 3 machines.
Today I've noticed that I can't ping these machines. And no: no iptables rules, policy is ACCEPT.
I can ssh into these machines. Other services like VNC are reachble, too.
With tcpdump I can see incoming icmp echo requests. But no answers from the machine.
This goes as far as I even can't ping 127.0.0.1 from inside! The machine also can't ping its own IPs on its interfaces.
I've been using Linux/Debian (desktop and server) for over 15 years now. But this is weird.
And it's reproducible on 3 maschines!
So is this a new "security feature" that I've missed?
Or a bug?