Here is part of an email I send to new users in our geo.  I do recommend you to request your AMPR coordinator to set an DNS entry for your main AMPR IP as well. --David KI6ZHD    - Example IPIP compatibility testing with a Linux computer: Consider you want to see if your ISP does or       doesn't block protocol 4 / IPIP traffic.          a. REQUIRED: Update the AMPR portal with the correct Internet IP address that will be terminating                       your IPIP tunnel.          b. RECOMMENDED: Send me (your AMPR coordinator) a hostname for at least one AMPR IP address you will             want to receive traffic.  I will enter these names into the reserve DNS interface.          c. Wait roughly 60 minutes until the IPIP mesh gets new routes for your information to propagate             through the AMPR mesh network          d. On your intended system that will be the AMPR IPIP endpoint, run the command:             #Assuming eth0 is your uplink port             tcpdump -nni eth0 proto 4          e. While tcpdump is running in one window on your Linux machine, open up a web browser using your             standard Internet connection to: http://yo2tm.ampr.org/nettools.php             Enter in the desired AMPR IP host address (not subnet address) you're using to terminate your             IPIP connection and click on "IPv4 ping".  If your ISP is properly forwarding you IPIP traffic,             your AMPR gateway should see something like the following on the tcpdump window:             --             13:12:15.876817 IP 89.122.215.236 > 96.78.144.186: IP 44.182.21.1 > 44.4.10.40: ICMP echo request, id 37699, seq 1, length 64 (ipip-proto-4)             13:12:15.877272 IP 96.78.144.186 > 89.122.215.236: IP 44.4.10.40 > 44.182.21.1: ICMP echo reply, id 37699, seq 1, length 64 (ipip-proto-4)             13:12:16.876362 IP 89.122.215.236 > 96.78.144.186: IP 44.182.21.1 > 44.4.10.40: ICMP echo request, id 37699, seq 2, length 64 (ipip-proto-4)             13:12:16.876788 IP 96.78.144.186 > 89.122.215.236: IP 44.4.10.40 > 44.182.21.1: ICMP echo reply, id 37699, seq 2, length 64 (ipip-proto-4)             13:12:17.876889 IP 89.122.215.236 > 96.78.144.186: IP 44.182.21.1 > 44.4.10.40: ICMP echo request, id 37699, seq 3, length 64 (ipip-proto-4)             --                                ^^^^^^^^^^^^^^ ^^^^^^^^^^^^^     ^^^^^^^^^^^   ^^^^^^^^^^                                yo2tm's public   your public       yo2tm's       your                                Internet addr Internet addr     AMPR addr     AMPR addr             If you don't see traffic like that, you either probably didn't set your Internet gateway IP             address on the AMPR portal correctly. Alternatively, your ISP is blocking IPIP traffic which             isn't all that uncommon.  There are ways around this with VPNs and what not so see the AMPR             Wiki (details below). On 01/07/2023 10:51 AM, kj7omo--- via 44net wrote: