Hi Marco, I remember in te old forum I asked for blocking the ICMP, and I still remember that @ms told me how, but sadly I can’t get to that old forum and I can’t find a hint for that nider on my pc.
If it’s a way to get to the old forum from ipfire i am shure you could find it.
But I think this link would help you:
ICMP
I think its the same thing that Michael Tremmer told me long ago.
Sins that time my ipfire is full stealth on grc.com.
Best regards,
Sharlon ( Neopegasus)