I agree with Rob.
For years, my node had similar behavior, causing various kinds of
intermittent issues. The problem was solved when I added an iptables
rule permitting inbound IPENCAP:
iptables -t filter -I INPUT -p 4 -i <INTERFACE OF YOUR WAN> -j ACCEPT
# For more security, there are scripts that will dynamically add
only AMPR node IPs seen in RIP44 updates.
It was discovered when others used my web-based ping and traceroute
tools from the Internet to their AMPR nodes, causing a stateful outbound
connection (of the IPENCAP packet); that this permitted the return
traffic from their nodes. Those who maintain a default route to the
Internet via AMPRGW don't usually notice this behavior from non-44 IPs;
because, generally, some packets from your Localhost have already
attempted to connect outbound (DNS, NTP, e-mail, messaging, Windows
Network Map, etc.), thereby establishing the stateful [firewall]
connection with AMPRGW.
NATed hosts must be connection tracked for outbound (which is why his
node can be reached by the remote after he initiates pings). "DMZ"
settings usually apply only to TCP and UDP (in most consumer devices, at
least). This is also further indication that our common recommendation
on this list for operators to place their AMPRGW in the DMZ may not be a
risk necessary to take. I should note, I've NEVER been able to use a
router with AMPRNet by simply enabling the "DMZ feature" on a consumer
device. We may need to compile a list of makes/models where the DMZ
feature works with IPENCAP.
73,
KB3VWG
PS: The above rule is on the firewall wiki page I'm working on; I'll add
details regarding why it's necessary to configure on a stateful firewall.