diff --git a/Messages.cpp b/Messages.cpp
index e9d7358..64c1663 100644
--- a/Messages.cpp
+++ b/Messages.cpp
@@ -33,22 +33,6 @@ unsigned char *IMessage::ReceiveMsg(unsigned char packetSize) {
 // IMessage
 #pragma endregion
 
-#pragma region Network Id
-
-NetworkIdMsg::NetworkIdMsg(char *buffer) { this->networkId = buffer[1]; }
-
-// void NetworkIdMsg::Deserialize(unsigned char *buffer) {
-//   this->networkId = buffer[1];
-// }
-
-NetworkIdMsg NetworkIdMsg::Receive(char *buffer, unsigned char bufferSize) {
-  NetworkIdMsg msg = NetworkIdMsg(buffer);
-  return msg;
-}
-
-// Network Id
-#pragma endregion
-
 #pragma region Investigate
 
 InvestigateMsg::InvestigateMsg(char *buffer) {
diff --git a/Messages.h b/Messages.h
index 37da6c1..b9ba569 100644
--- a/Messages.h
+++ b/Messages.h
@@ -21,17 +21,6 @@ public:
   // bool SendTo(Participant *participant);
 };
 
-class NetworkIdMsg : public IMessage {
-public:
-  static const unsigned char id = 0xA1;
-  static const unsigned char length = 2;
-  unsigned char networkId;
-
-  NetworkIdMsg(char *buffer);
-
-  static NetworkIdMsg Receive(char *buffer, unsigned char bufferSize);
-};
-
 class InvestigateMsg : public IMessage {
 public:
   static const unsigned char id = 0x81;
diff --git a/NetworkIdMsg.cpp b/NetworkIdMsg.cpp
new file mode 100644
index 0000000..69234ef
--- /dev/null
+++ b/NetworkIdMsg.cpp
@@ -0,0 +1,25 @@
+#include "NetworkIdMsg.h"
+
+namespace Passer {
+namespace Control {
+
+NetworkIdMsg::NetworkIdMsg(const char *buffer) { this->networkId = buffer[1]; }
+
+NetworkIdMsg::NetworkIdMsg(unsigned char networkId) {
+  this->networkId = networkId;
+}
+
+unsigned char NetworkIdMsg::Serialize(char *buffer) {
+  unsigned char ix = 0;
+  buffer[ix++] = this->id;
+  buffer[ix++] = this->networkId;
+  return NetworkIdMsg::length;
+}
+
+// NetworkIdMsg NetworkIdMsg::Receive(char *buffer, unsigned char bufferSize) {
+//   NetworkIdMsg msg = NetworkIdMsg(buffer);
+//   return msg;
+// }
+
+} // namespace Control
+} // namespace Passer
\ No newline at end of file
diff --git a/NetworkIdMsg.h b/NetworkIdMsg.h
new file mode 100644
index 0000000..81cb4f0
--- /dev/null
+++ b/NetworkIdMsg.h
@@ -0,0 +1,20 @@
+#include "Messages.h"
+
+namespace Passer {
+namespace Control {
+
+class NetworkIdMsg : public IMessage {
+public:
+  static const unsigned char id = 0xA1;
+  static const unsigned char length = 2;
+  unsigned char networkId;
+
+  NetworkIdMsg(const char *buffer);
+  NetworkIdMsg(unsigned char networkId);
+
+  virtual unsigned char Serialize(char *buffer) override;
+  // static NetworkIdMsg Receive(char *buffer, unsigned char bufferSize);
+};
+
+} // namespace Control
+} // namespace Passer
diff --git a/Participant.cpp b/Participant.cpp
index dce6631..28cc070 100644
--- a/Participant.cpp
+++ b/Participant.cpp
@@ -21,6 +21,15 @@ Participant::Participant(const char *ipAddress, int port) {
   this->ipAddress = ipAddress;
   this->port = port;
 
+  this->participants.push_back(this);
+
+  int randomPort = (rand() % (65535 - 49152 + 1)) + 49152;
+  SetupUDP(randomPort, ipAddress, port);
+}
+
+void Passer::Control::Participant::SetupUDP(int localPort,
+                                            const char *remoteIpAddress,
+                                            int remotePort) {
   // Create a UDP socket
 #if defined(_WIN32) || defined(_WIN64)
   // Windows-specific Winsock initialization
@@ -42,27 +51,58 @@ Participant::Participant(const char *ipAddress, int port) {
     return;
   }
 
-  // Set up the server address
+// Set the socket to non-blocking mode
+#if defined(_WIN32) || defined(_WIN64)
+  u_long mode = 1; // 1 to enable non-blocking socket
+  ioctlsocket(this->sock, FIONBIO, &mode);
+#elif defined(__unix__) || defined(__APPLE__)
+  int flags = fcntl(this->sock, F_GETFL, 0);
+  fcntl(this->sock, F_SETFL, flags | O_NONBLOCK);
+#endif
+
+  if (remotePort != 0) {
+    // Set up the address to send to
+    memset(&remote_addr, 0, sizeof(remote_addr));
+    remote_addr.sin_family = AF_INET;
+    remote_addr.sin_port = htons((u_short)remotePort);
+    if (inet_pton(AF_INET, remoteIpAddress, &remote_addr.sin_addr) <= 0) {
+      std::cerr << "Invalid address" << std::endl;
+      closesocket(sock);
+      WSACleanup();
+      return;
+    }
+  }
+
+  // Set up the receiving address
   memset(&server_addr, 0, sizeof(server_addr));
   server_addr.sin_family = AF_INET;
-  server_addr.sin_port = htons((u_short)port); // Port to send the packet to
-  if (inet_pton(AF_INET, ipAddress, &server_addr.sin_addr) <= 0) {
+  server_addr.sin_port = htons((u_short)localPort);
+  if (inet_pton(AF_INET, "0.0.0.0", &server_addr.sin_addr) <= 0) {
     std::cerr << "Invalid address" << std::endl;
     closesocket(sock);
     WSACleanup();
     return;
   }
 
+  // Bind the socket to the specified port
+  if (bind(this->sock, (const struct sockaddr *)&server_addr,
+           sizeof(server_addr)) < 0) {
+    std::cerr << "Bind failed" << std::endl;
+    closesocket(this->sock);
+    return;
+  }
+
   // Set up the broadcast address
   memset(&broadcast_addr, 0, sizeof(broadcast_addr));
   broadcast_addr.sin_family = AF_INET;
-  broadcast_addr.sin_port = htons((u_short)port); // Port to send the packet to
+  broadcast_addr.sin_port = htons((u_short)remotePort);
   if (inet_pton(AF_INET, "255.255.255.255", &broadcast_addr.sin_addr) <= 0) {
     std::cerr << "Invalid address" << std::endl;
     closesocket(sock);
     WSACleanup();
     return;
   }
+
   BOOL broadcast = TRUE;
   if (setsockopt(sock, SOL_SOCKET, SO_BROADCAST, (char *)&broadcast,
                  sizeof(broadcast)) == SOCKET_ERROR) {
@@ -71,14 +111,65 @@ Participant::Participant(const char *ipAddress, int port) {
 }
 
 void Participant::Update(unsigned long currentTimeMs) {
-  // std::cout << "update\n";
   if (currentTimeMs > this->nextPublishMe) {
-    ClientMsg msg = ClientMsg(this->networkId);
-    this->Publish(&msg);
-    // Console.WriteLine($"{this.name} Sent ClientMsg {this.networkId}");
-    std::cout << this->name << " sent ClientMsg\n";
+    this->Publish(&ClientMsg(this->networkId));
+    std::cout << this->name << " published ClientMsg\n";
     this->nextPublishMe = currentTimeMs + this->publishInterval;
   }
+  this->ReceiveUDP();
+
+  Thing::UpdateAll(currentTimeMs);
+}
+
+void Participant::ReceiveUDP() {
+  // char ip_str[INET_ADDRSTRLEN];
+  // inet_ntop(AF_INET, &(server_addr.sin_addr), ip_str, INET_ADDRSTRLEN);
+  // std::cout << this->name << " Receive on " << ip_str << ":"
+  //           << ntohs(server_addr.sin_port) << "\n";
+
+  sockaddr_in client_addr;
+  int len = sizeof(client_addr);
+  int packetSize = recvfrom(this->sock, buffer, sizeof(buffer), 0,
+                            (struct sockaddr *)&client_addr, &len);
+  // std::cout << "received data " << packetSize << "\n";
+  if (packetSize < 0) {
+    int error_code = WSAGetLastError(); // Get the error code on Windows
+    if (error_code != WSAEWOULDBLOCK)
+      std::cerr << "recvfrom failed with error: " << error_code << std::endl;
+
+  } else if (packetSize > 0) {
+    char sender_ipAddress[INET_ADDRSTRLEN];
+    inet_ntop(AF_INET, &(client_addr.sin_addr), sender_ipAddress,
+              INET_ADDRSTRLEN);
+    int sender_port = ntohs(client_addr.sin_port);
+
+    Participant *remoteParticipant =
+        this->GetParticipant(sender_ipAddress, sender_port);
+    if (remoteParticipant == nullptr) {
+      remoteParticipant = this->AddParticipant(sender_ipAddress, sender_port);
+      std::cout << "New remote participant " << sender_ipAddress << ":"
+                << sender_port << " "
+                << (unsigned char)remoteParticipant->networkId << "|\n";
+    }
+
+    ReceiveData(packetSize, remoteParticipant);
+  }
+}
+
+Participant *Participant::GetParticipant(const char *ipAddress, int port) {
+  for (Participant *participant : this->participants) {
+    if (participant->ipAddress == ipAddress && participant->port == port)
+      return participant;
+  }
+  return nullptr;
+}
+
+Participant *Participant::AddParticipant(const char *ipAddress, int port) {
+  Participant *participant = new Participant(ipAddress, port);
+  participant->networkId = (unsigned char)this->participants.size();
+  std::cout << "nw id " << (unsigned char)participant->networkId << "\n";
+  this->participants.push_back(participant);
+  return participant;
 }
 
 #pragma region Send
@@ -100,16 +191,16 @@ void Participant::SendThingInfo(Thing *thing) {
 bool Participant::Send(IMessage *msg) {
   // Send the message to the specified address and port
   int bufferSize = msg->Serialize(this->buffer);
-  std::cout << "buffer size " << bufferSize << "\n";
+  // std::cout << "buffer size " << bufferSize << "\n";
   if (bufferSize <= 0)
     return true;
 
-  // char ip_str[INET_ADDRSTRLEN];
-  // inet_ntop(AF_INET, &(server_addr.sin_addr), ip_str, INET_ADDRSTRLEN);
-  // std::cout << "Publish to " << ip_str << ":" << ntohs(server_addr.sin_port)
-  //           << "\n";
+  char ip_str[INET_ADDRSTRLEN];
+  inet_ntop(AF_INET, &(server_addr.sin_addr), ip_str, INET_ADDRSTRLEN);
+  std::cout << "Publish to " << ip_str << ":" << ntohs(server_addr.sin_port)
+            << "\n";
   int sent_bytes = sendto(sock, this->buffer, bufferSize, 0,
-                          (struct sockaddr *)&server_addr, sizeof(server_addr));
+                          (struct sockaddr *)&remote_addr, sizeof(remote_addr));
   if (sent_bytes == SOCKET_ERROR) {
     int error_code = WSAGetLastError(); // Get the error code on Windows
     std::cerr << "sendto failed with error: " << error_code << std::endl;
@@ -121,16 +212,14 @@ bool Participant::Send(IMessage *msg) {
 }
 
 bool Participant::Publish(IMessage *msg) {
-  // Send the message to the specified address and port
   int bufferSize = msg->Serialize(this->buffer);
-  std::cout << "buffer size " << bufferSize << "\n";
   if (bufferSize <= 0)
     return true;
 
-  // char ip_str[INET_ADDRSTRLEN];
-  // inet_ntop(AF_INET, &(server_addr.sin_addr), ip_str, INET_ADDRSTRLEN);
-  // std::cout << "Publish to " << ip_str << ":" << ntohs(server_addr.sin_port)
-  //           << "\n";
+  char ip_str[INET_ADDRSTRLEN];
+  inet_ntop(AF_INET, &(broadcast_addr.sin_addr), ip_str, INET_ADDRSTRLEN);
+  std::cout << "Publish to " << ip_str << ":" << ntohs(broadcast_addr.sin_port)
+            << "\n";
   int sent_bytes =
       sendto(sock, this->buffer, bufferSize, 0,
              (struct sockaddr *)&broadcast_addr, sizeof(broadcast_addr));
@@ -181,8 +270,8 @@ void Participant::ReceiveData(unsigned char bufferSize,
 void Participant::Process(Participant *sender, ClientMsg *msg) {}
 
 void Participant::Process(Participant *sender, NetworkIdMsg *msg) {
-  std::cout << this->name << " receive network id " << this->networkId << " "
-            << msg->networkId << "\n";
+  std::cout << this->name << " receive network id " << (int)this->networkId
+            << " " << msg->networkId << "\n";
   if (this->networkId != msg->networkId) {
     this->networkId = msg->networkId;
     Thing **allThings = Thing::GetAllThings();
diff --git a/Participant.h b/Participant.h
index 83f927e..1f99129 100644
--- a/Participant.h
+++ b/Participant.h
@@ -4,8 +4,11 @@
 #include "Messages.h"
 #include "ModelUrlMsg.h"
 #include "NameMsg.h"
+#include "NetworkIdMsg.h"
 #include "ThingMsg.h"
 
+#include <list>
+
 #if defined(_WIN32) || defined(_WIN64)
 #include <winsock2.h>
 #endif
@@ -26,6 +29,7 @@ public:
   int port = 0;
 
   SOCKET sock;
+  sockaddr_in remote_addr;
   sockaddr_in server_addr;
   sockaddr_in broadcast_addr;
 
@@ -42,8 +46,17 @@ public:
   void ReceiveData(unsigned char bufferSize, Participant *remoteParticipant);
 
 protected:
+  std::list<Participant *> participants;
+
   unsigned long nextPublishMe = 0;
 
+  void SetupUDP(int localPort, const char *remoteIpAddress, int remotePort);
+
+  Participant *GetParticipant(const char *ipAddress, int port);
+  Participant *AddParticipant(const char *ipAddress, int port);
+
+  void ReceiveUDP();
+
   virtual void Process(Participant *sender, ClientMsg *msg);
   virtual void Process(Participant *sender, NetworkIdMsg *msg);
   virtual void ProcessInvestigateMsg(InvestigateMsg msg);
diff --git a/SiteServer.cpp b/SiteServer.cpp
index 15721ac..e75e076 100644
--- a/SiteServer.cpp
+++ b/SiteServer.cpp
@@ -5,16 +5,22 @@ Passer::Control::SiteServer::SiteServer(int port) {
 
   this->ipAddress = "0.0.0.0";
   this->port = port;
+
+  this->participants.push_back(this);
+
+  SetupUDP(port, ipAddress, 0);
 }
 
 void Passer::Control::SiteServer::Update(unsigned long currentTimeMs) {
+  this->ReceiveUDP();
   Thing::UpdateAll(currentTimeMs);
 }
 
 void Passer::Control::SiteServer::Process(Participant *sender, ClientMsg *msg) {
   if (msg->networkId == 0) {
-    std::cout << this->name << " received New Client -> " << sender->networkId
-              << "\n";
+    std::cout << this->name << " received New Client -> "
+              << (unsigned char)sender->networkId << "\n";
+    sender->Send(&NetworkIdMsg(sender->networkId));
   }
 }
 
diff --git a/test/thing_test.cc b/test/thing_test.cc
index d38fad4..e261fb5 100644
--- a/test/thing_test.cc
+++ b/test/thing_test.cc
@@ -5,6 +5,7 @@
 #include <gtest/gtest.h>
 
 #include <chrono>
+#include <thread>
 #include <ws2tcpip.h>
 
 #include "Participant.h"
@@ -60,5 +61,21 @@ TEST_F(ControlCoreSuite, SiteServer) {
   ASSERT_EQ(1, 1);
 }
 
+TEST_F(ControlCoreSuite, SiteParticipant) {
+  SiteServer site = SiteServer(7681);
+  Participant participant = Participant("127.0.0.1", 7681);
+
+  unsigned long milliseconds = get_time_ms();
+  unsigned long startTime = milliseconds;
+  while (milliseconds < startTime + 1000) {
+    site.Update(milliseconds);
+    participant.Update(milliseconds);
+
+    std::this_thread::sleep_for(std::chrono::milliseconds(100));
+    milliseconds = get_time_ms();
+  }
+  ASSERT_EQ(1, 1);
+}
+
 } // namespace Passer
 #endif