Change default UDP port to 2121 and EtherType to 0x2121

Update the default UDP bind port from 4000 to 2121 (decimal) and the
default Ethernet EtherType from 0x88B5 to 0x2121 across all source
code, documentation, configuration templates, test fixtures, and
scripts. Remove references to "IEEE 802 experimental range" since
0x2121 is not in that range.

testing/chaos/configs/node.template.yaml

@@ -17,7 +17,7 @@ dns:
 
 transports:
   udp:
-    bind_addr: "0.0.0.0:4000"
+    bind_addr: "0.0.0.0:2121"
     mtu: 1472
     # recv_buf_size: 2097152   # 2 MB (default)
     # send_buf_size: 2097152   # 2 MB (default)

testing/chaos/sim/config_gen.py

@@ -49,7 +49,7 @@ def generate_peers_block(
         lines.append(f'    alias: "{peer_id}"')
         lines.append(f"    addresses:")
         lines.append(f"      - transport: udp")
-        lines.append(f'        addr: "{peer.docker_ip}:4000"')
+        lines.append(f'        addr: "{peer.docker_ip}:2121"')
         lines.append(f"    connect_policy: auto_connect")
     return "\n".join(lines)
 

testing/static/README.md

@@ -306,7 +306,7 @@ removing rules first.
 - **Capabilities**: `CAP_NET_ADMIN` (for TUN device creation)
 - **Devices**: `/dev/net/tun` mapped into each container
 - **DNS**: FIPS built-in resolver on `127.0.0.1:53`
-- **Transport**: UDP on port 4000, MTU 1472
+- **Transport**: UDP on port 2121, MTU 1472
 - **TUN**: `fips0` interface, MTU 1280
 
 Each node resolves `<npub>.fips` DNS names to FIPS IPv6 addresses via its

testing/static/configs/node.template.yaml

@@ -17,7 +17,7 @@ dns:
 
 transports:
   udp:
-    bind_addr: "0.0.0.0:4000"
+    bind_addr: "0.0.0.0:2121"
     mtu: 1472
     # recv_buf_size: 2097152   # 2 MB (default)
     # send_buf_size: 2097152   # 2 MB (default)

testing/static/docker-chain-topology.svg

@@ -101,7 +101,7 @@
   <rect x="30" y="260" width="640" height="120" class="legend-box"/>
 
   <line x1="50" y1="282" x2="90" y2="282" stroke="#506090" stroke-width="2"/>
-  <text x="100" y="286" class="legend">Direct UDP peer link (port 4000, auto_connect)</text>
+  <text x="100" y="286" class="legend">Direct UDP peer link (port 2121, auto_connect)</text>
 
   <line x1="50" y1="304" x2="90" y2="304" stroke="#d0a040" stroke-width="1.2"
         stroke-dasharray="5 3" marker-end="url(#arrow)"/>

testing/static/docker-mesh-topology.svg

@@ -117,7 +117,7 @@
   <rect x="40" y="410" width="620" height="130" class="legend-box"/>
 
   <line x1="60" y1="435" x2="100" y2="435" stroke="#404860" stroke-width="1.5"/>
-  <text x="110" y="439" class="legend">UDP peer link (port 4000, auto_connect)</text>
+  <text x="110" y="439" class="legend">UDP peer link (port 2121, auto_connect)</text>
 
   <line x1="55" y1="457" x2="100" y2="457" stroke="#60a0e0" stroke-width="2"/>
   <path d="M 90 454 L 100 457 L 90 460 z" fill="#60a0e0"/>

testing/static/scripts/generate-configs.sh

@@ -89,7 +89,7 @@ generate_peer_block() {
     alias: "node-$peer_id"
     addresses:
       - transport: udp
-        addr: "$peer_ip:4000"
+        addr: "$peer_ip:2121"
     connect_policy: auto_connect
 EOF
 }