Rather use a locally-hosted Ubuntu Echo Server as Buffalo Creek Wirel…

…ess rejects all outgoing/incoming packets forwarded on behalf of my MCU. Evidenced as:

	# Before connecting MCU to Ubuntu Ethernet Interface:
	(py37-venv) nuertey@nuertey-PC-LL850RSB:~$ sudo iptables -S -v
	-P INPUT ACCEPT -c 16 2682
	-P FORWARD ACCEPT -c 0 0
	-P OUTPUT ACCEPT -c 18 2762
	-A INPUT -i enp3s0 -c 0 0 -j ACCEPT
	-A FORWARD -i enp3s0 -c 0 0 -j ACCEPT
	-A OUTPUT -o enp3s0 -c 0 0 -j ACCEPT

	# After connecting MCU to Ubuntu Ethernet Interface:
	(py37-venv) nuertey@nuertey-PC-LL850RSB:~$ sudo iptables -S -v
	-P INPUT ACCEPT -c 608 90252
	-P FORWARD ACCEPT -c 0 0
	-P OUTPUT ACCEPT -c 673 84599
	-A INPUT -i enp3s0 -p udp -m udp --dport 67 -c 4 1344 -j ACCEPT
	-A INPUT -i enp3s0 -p tcp -m tcp --dport 67 -c 0 0 -j ACCEPT
	-A INPUT -i enp3s0 -p udp -m udp --dport 53 -c 0 0 -j ACCEPT
	-A INPUT -i enp3s0 -p tcp -m tcp --dport 53 -c 0 0 -j ACCEPT
	-A INPUT -i enp3s0 -c 21 3296 -j ACCEPT
	-A FORWARD -d 10.42.0.0/24 -o enp3s0 -m state --state RELATED,ESTABLISHED -c 38 2262 -j ACCEPT
	-A FORWARD -s 10.42.0.0/24 -i enp3s0 -c 10 510 -j ACCEPT
	-A FORWARD -i enp3s0 -o enp3s0 -c 0 0 -j ACCEPT
	-A FORWARD -o enp3s0 -c 0 0 -j REJECT --reject-with icmp-port-unreachable
	-A FORWARD -i enp3s0 -c 0 0 -j REJECT --reject-with icmp-port-unreachable
	-A FORWARD -i enp3s0 -c 0 0 -j ACCEPT
	-A OUTPUT -o enp3s0 -c 27 4688 -j ACCEPT

Utilities.h

@@ -148,6 +148,16 @@ namespace Utilities
                 // as we are emplace'ing:
                 ipAddress.emplace(pTheSocketAddress->get_ip_address());
             }
+            else
+            {
+                // Assume that we are already dealing with an IP address. i.e.,
+                // as the designer of this application, I am mandating that the
+                // user can choose to specify IP addresses directly in the mbed_app.json
+                // echo-server-hostname field. This will facilitate testing with
+                // locally hosted Echo Servers, which by necessity, do not have 
+                // DNS names.
+                ipAddress.emplace(address.c_str()); 
+            }
         }
 
         return ipAddress;

mbed_app.json

@@ -7,7 +7,7 @@
         "sock-type": "NUERTEY_TCP",
         "echo-server-hostname": {
             "help": "Echo server host name.",
-            "value": "\"echo.mbedcloudtesting.com\""
+            "value": "\"10.50.10.25\""
         },
         "echo-server-port": {
             "help": "Echo server port number.",