diff --git a/main.go b/main.go
index b8d8f69..51eacee 100644
--- a/main.go
+++ b/main.go
@@ -5,6 +5,7 @@ import (
 	"wwfc/gpcm"
 	"wwfc/gpsp"
 	"wwfc/nas"
+	"wwfc/natneg"
 	"wwfc/qr2"
 	"wwfc/sake"
 	"wwfc/serverbrowser"
@@ -12,7 +13,7 @@ import (
 
 func main() {
 	wg := &sync.WaitGroup{}
-	actions := []func(){nas.StartServer, gpcm.StartServer, qr2.StartServer, gpsp.StartServer, serverbrowser.StartServer, sake.StartServer}
+	actions := []func(){nas.StartServer, gpcm.StartServer, qr2.StartServer, gpsp.StartServer, serverbrowser.StartServer, sake.StartServer, natneg.StartServer}
 	wg.Add(5)
 	for _, action := range actions {
 		go func(ac func()) {
diff --git a/natneg/main.go b/natneg/main.go
new file mode 100644
index 0000000..a43f02a
--- /dev/null
+++ b/natneg/main.go
@@ -0,0 +1,149 @@
+package natneg
+
+import (
+	"bytes"
+	"encoding/binary"
+	"fmt"
+	"github.com/logrusorgru/aurora/v3"
+	"net"
+	"wwfc/common"
+	"wwfc/logging"
+)
+
+const (
+	NNInitRequest         = 0x00
+	NNInitReply           = 0x01
+	NNErtTestRequest      = 0x02
+	NNErtTestReply        = 0x03
+	NNStateUpdate         = 0x04
+	NNConnectRequest      = 0x05
+	NNConnectReply        = 0x06
+	NNConnectPing         = 0x07
+	NNBackupTestRequest   = 0x08
+	NNBackupTestReply     = 0x09
+	NNAddressCheckRequest = 0x0A
+	NNAddressCheckReply   = 0x0B
+	NNNatifyRequest       = 0x0C
+	NNReportRequest       = 0x0D
+	NNReportReply         = 0x0E
+	NNPreInitRequest      = 0x0F
+	NNPreInitReply        = 0x10
+)
+
+func StartServer() {
+	// Get config
+	config := common.GetConfig()
+
+	address := config.Address + ":27901"
+	conn, err := net.ListenPacket("udp", address)
+	if err != nil {
+		panic(err)
+	}
+
+	// Close the listener when the application closes.
+	defer conn.Close()
+	logging.Notice("NATNEG", "Listening on", address)
+
+	for {
+		buf := make([]byte, 1024)
+		_, addr, err := conn.ReadFrom(buf)
+		if err != nil {
+			continue
+		}
+
+		go handleConnection(conn, addr, buf)
+	}
+}
+
+func handleConnection(conn net.PacketConn, addr net.Addr, buffer []byte) {
+	// Validate the packet magic
+	if bytes.Equal(buffer[:6], []byte{0xfd, 0xfc, 0x1e, 0x66, 0x6a, 0xb2}) {
+		logging.Error("NATNEG:"+addr.String(), "Invalid packet header")
+		return
+	}
+
+	// Parse the NATNEG header
+	// fd fc 1e 66 6a b2 - Packet Magic
+	// xx                - Version
+	// xx                - Packet Type / Command
+	// xx xx xx xx       - Cookie
+
+	// version := buffer[6]
+	command := buffer[7]
+	cookie := binary.BigEndian.Uint32(buffer[8:12])
+
+	moduleName := "NATNEG:" + fmt.Sprintf("%08x", cookie) + addr.String() + ":"
+
+	switch command {
+	default:
+		logging.Error(moduleName, "Received unknown command type:", aurora.Cyan(command))
+
+	case NNInitRequest:
+		logging.Notice(moduleName, "Command:", aurora.Yellow("NNInitRequest"))
+		break
+
+	case NNInitReply:
+		logging.Warn(moduleName, "Received server command:", aurora.Yellow("NNInitReply"))
+		break
+
+	case NNErtTestRequest:
+		logging.Warn(moduleName, "Received server command:", aurora.Yellow("NNErtTestRequest"))
+		break
+
+	case NNErtTestReply:
+		logging.Notice(moduleName, "Command:", aurora.Yellow("NNErtReply"))
+		break
+
+	case NNStateUpdate:
+		logging.Notice(moduleName, "Command:", aurora.Yellow("NNStateUpdate"))
+		break
+
+	case NNConnectRequest:
+		logging.Warn(moduleName, "Received server command:", aurora.Yellow("NNConnectRequest"))
+		break
+
+	case NNConnectReply:
+		logging.Notice(moduleName, "Command:", aurora.Yellow("NNConnectReply"))
+		break
+
+	case NNConnectPing:
+		logging.Notice(moduleName, "Command:", aurora.Yellow("NNConnectPing"))
+		break
+
+	case NNBackupTestRequest:
+		logging.Notice(moduleName, "Command:", aurora.Yellow("NNBackupTestRequest"))
+		break
+
+	case NNBackupTestReply:
+		logging.Warn(moduleName, "Received server command:", aurora.Yellow("NNBackupTestReply"))
+		break
+
+	case NNAddressCheckRequest:
+		logging.Notice(moduleName, "Command:", aurora.Yellow("NNAddressCheckRequest"))
+		break
+
+	case NNAddressCheckReply:
+		logging.Warn(moduleName, "Received server command:", aurora.Yellow("NNAddressCheckReply"))
+		break
+
+	case NNNatifyRequest:
+		logging.Notice(moduleName, "Command:", aurora.Yellow("NNNatifyRequest"))
+		break
+
+	case NNReportRequest:
+		logging.Notice(moduleName, "Command:", aurora.Yellow("NNReportRequest"))
+		break
+
+	case NNReportReply:
+		logging.Warn(moduleName, "Received server command:", aurora.Yellow("NNReportReply"))
+		break
+
+	case NNPreInitRequest:
+		logging.Notice(moduleName, "Command:", aurora.Yellow("NNPreInitRequest"))
+		break
+
+	case NNPreInitReply:
+		logging.Warn(moduleName, "Received server command:", aurora.Yellow("NNPreInitReply"))
+		break
+	}
+}