Thanks for the info folks. I have followed Headrooms' suggestion of having a name associated with my dynamic 4-byte IP address.
Telnetting from inside my LAN to the Ethernet-Arduino still works fine. Wireshark shows two Address Resolution Protocol frames:
- my computer broadcasts a 'Who has (Ethernet_Arduino IP address), tell (my computer IP address)' ARP request.
- my Ethernet-Arduino addresses my computer with 'its IP address is at its MAC address' ARP reply.
Then TCP & TELNET protocol frames continue in what I expect is normal behavior (I'm happy with it).
Telnetting into my LAN to the Ethernet-Arduino seems to get stuck in the ARP protocol sequence. This time it's my router
(I think) that is issuing the 'Who is' ARP request. It seems to be cycling through typical IP address'. When it hits my
computers address my computer responds with an ARP reply (as the Ethernet-Arduino did when addresses from within my LAN).
So, the Ethernet_Arduino issues ARP protocol replies when addressed directly from my LAN but not automatically when addressed
from the internet? Any ideas? Alex.
P.S. My router (BT Homehub 2) gave this DMZ warning...
DMZ - assign the public IP address of a connection to a device on your home network.
You can use this feature when you're troubleshooting a device or application.
However, in most cases, we recommend that you use Port Forwarding instead.
Important: using this feature can have a serious impact on your Hub and the security of your network.
The device that you've assigned to the internet service will no longer be protected by your Hub's firewall.
We recommend that you only use this feature as a temporary measure while troubleshooting.
Hosts with statically assigned IP addresses cannot be placed into DMZ mode.