Init commit with many years of arduino sketches and projects. I dont know if the esp8266 includes much, but there are also libraries. I hope they dont have crazy automatic versioning through the Arduino IDE.

Projects/libraries/Installed_libs/Ethernet/examples/UdpReceiveString/UdpReceiveString.pde

@@ -0,0 +1,58 @@
+#include <Ethernet.h>
+#include <UdpString.h>
+#include <WString.h>
+/* UdpReceiveString.pde: Example how to receive packets over UDP using the UdpString library
+ * prints received packet to serial port
+ * bjoern@cs.stanford.edu 12/30/2008
+ */
+
+/* ETHERNET SHIELD CONFIGURATION  
+ * set MAC, IP address of Ethernet shield, its gateway,
+ * and local port to listen on for incoming packets 
+ */
+byte mac[] = { 0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED }; // MAC address to use
+byte ip[] = { 192, 168, 11, 200 }; // Arduino's IP address
+byte gw[] = { 192, 168, 11, 1 };   // Gateway IP address
+int localPort = 8888; // local port to listen on
+
+String packet(32); //packet can be max 32 bytes long
+byte remoteIp[4]; // holds recvieved packet's originating IP
+unsigned int remotePort[1]; // holds received packet's originating port
+
+int i;
+
+/* SETUP: init Ethernet shield, start UDP listening, open serial port */
+void setup() {
+  Ethernet.begin(mac,ip,gw);
+  UdpString.begin(localPort);
+  Serial.begin(38400); 
+}
+
+/* LOOP: wait for incoming packets and print each packet to the serial port */
+void loop() {  
+
+  // if there's data available, read a packet
+  if(UdpString.available()) {
+    int packetSize = UdpString.readPacket(packet,remoteIp,remotePort);
+
+    Serial.print("Received packet of size ");
+    Serial.println(packetSize);
+
+    Serial.print("From IP ");
+    for(i=0; i<3; i++) {
+      Serial.print(remoteIp[i],DEC);
+      Serial.print(".");
+    }
+    Serial.print(remoteIp[3],DEC);
+
+    Serial.print(" Port ");
+    Serial.println(remotePort[0]); 
+
+    Serial.println("Contents:");
+    Serial.println(packet);
+
+
+  }
+  //wait a bit
+  delay(10);  
+}