diff --git a/cmd/control.go b/cmd/control.go
index 69bbc0e..c56fed9 100644
--- a/cmd/control.go
+++ b/cmd/control.go
@@ -9,6 +9,9 @@ import (
 	common "github.com/kerwenwwer/xdp-gossip/common"
 )
 
+const errMsgInvalidRequestMethod = "Invalid request method"
+const errMsgErrorWritingResponse = "Error writing response"
+
 /*
  * HTTP server for XDP Gossip control plane.
  */
@@ -19,7 +22,7 @@ import (
 func (nl *NodeList) ListNodeHandler() http.HandlerFunc {
 	return func(w http.ResponseWriter, r *http.Request) {
 		if r.Method != http.MethodGet {
-			http.Error(w, "Invalid request method", http.StatusMethodNotAllowed)
+			http.Error(w, errMsgInvalidRequestMethod, http.StatusMethodNotAllowed)
 			return
 		}
 
@@ -42,7 +45,7 @@ func (nl *NodeList) ListNodeHandler() http.HandlerFunc {
 func (nl *NodeList) StopNodeHandler() http.HandlerFunc {
 	return func(w http.ResponseWriter, r *http.Request) {
 		if r.Method != http.MethodGet {
-			http.Error(w, "Invalid request method", http.StatusMethodNotAllowed)
+			http.Error(w, errMsgInvalidRequestMethod, http.StatusMethodNotAllowed)
 			return
 		}
 
@@ -52,7 +55,7 @@ func (nl *NodeList) StopNodeHandler() http.HandlerFunc {
 		w.WriteHeader(http.StatusOK)
 		_, err := w.Write([]byte("Node stopped successfully.\n"))
 		if err != nil {
-			log.Println("Error writing response")
+			log.Println(errMsgErrorWritingResponse)
 			return
 		}
 	}
@@ -62,7 +65,7 @@ func (nl *NodeList) StopNodeHandler() http.HandlerFunc {
 func (nl *NodeList) GetMetadataHandler() http.HandlerFunc {
 	return func(w http.ResponseWriter, r *http.Request) {
 		if r.Method != http.MethodGet {
-			http.Error(w, "Invalid request method", http.StatusMethodNotAllowed)
+			http.Error(w, errMsgInvalidRequestMethod, http.StatusMethodNotAllowed)
 			return
 		}
 
@@ -86,7 +89,7 @@ func (nl *NodeList) GetMetadataHandler() http.HandlerFunc {
 func (nl *NodeList) PublishHandler() http.HandlerFunc {
 	return func(w http.ResponseWriter, r *http.Request) {
 		if r.Method != http.MethodPost {
-			http.Error(w, "Invalid request method", http.StatusMethodNotAllowed)
+			http.Error(w, errMsgInvalidRequestMethod, http.StatusMethodNotAllowed)
 			return
 		}
 
@@ -104,7 +107,7 @@ func (nl *NodeList) PublishHandler() http.HandlerFunc {
 		w.WriteHeader(http.StatusOK)
 		_, err = w.Write([]byte("[Control]: Data published successfully.\n"))
 		if err != nil {
-			log.Println("Error writing response")
+			log.Println(errMsgErrorWritingResponse)
 			return
 		}
 	}
@@ -114,7 +117,7 @@ func (nl *NodeList) PublishHandler() http.HandlerFunc {
 func (nl *NodeList) SetNodeHandler() http.HandlerFunc {
 	return func(w http.ResponseWriter, r *http.Request) {
 		if r.Method != http.MethodPost {
-			http.Error(w, "Invalid request method", http.StatusMethodNotAllowed)
+			http.Error(w, errMsgInvalidRequestMethod, http.StatusMethodNotAllowed)
 			return
 		}
 
@@ -140,7 +143,7 @@ func (nl *NodeList) SetNodeHandler() http.HandlerFunc {
 		w.WriteHeader(http.StatusOK)
 		_, err = w.Write([]byte("Node list updated successfully.\n"))
 		if err != nil {
-			log.Println("Error writing response")
+			log.Println(errMsgErrorWritingResponse)
 			return
 		}
 	}
diff --git a/cmd/opt.go b/cmd/opt.go
index 76465c4..8b1c46e 100644
--- a/cmd/opt.go
+++ b/cmd/opt.go
@@ -7,6 +7,8 @@ import (
 	common "github.com/kerwenwwer/xdp-gossip/common"
 )
 
+const errMsgControlErrorPrefix = "[Control Error]:"
+
 // New initializes the local node list
 func (nodeList *NodeList) New(localNode common.Node) {
 
@@ -71,7 +73,7 @@ func (nodeList *NodeList) Join() {
 
 	// If the local node list of this node has not been initialized
 	if len(nodeList.localNode.Addr) == 0 {
-		nodeList.println("[Control Error]:", "New() a nodeList before Join().")
+		nodeList.println(errMsgControlErrorPrefix, "New() a nodeList before Join().")
 		// Directly return
 		return
 	}
@@ -96,7 +98,7 @@ func (nodeList *NodeList) Stop() {
 
 	// If the local node list of this node has not been initialized
 	if len(nodeList.localNode.Addr) == 0 {
-		nodeList.println("[Control Error]:", "New() a nodeList before Stop().")
+		nodeList.println(errMsgControlErrorPrefix, "New() a nodeList before Stop().")
 		// Return directly
 		return
 	}
@@ -110,7 +112,7 @@ func (nodeList *NodeList) Start() {
 
 	// If the local node list of this node has not been initialized
 	if len(nodeList.localNode.Addr) == 0 {
-		nodeList.println("[Control Error]:", "New() a nodeList before Start().")
+		nodeList.println(errMsgControlErrorPrefix, "New() a nodeList before Start().")
 		// Return directly
 		return
 	}
@@ -131,7 +133,7 @@ func (nodeList *NodeList) Set(node common.Node) {
 
 	// If the local node list of this node has not been initialized
 	if len(nodeList.localNode.Addr) == 0 {
-		nodeList.println("[Control Error]:", "New() a nodeList before Set().")
+		nodeList.println(errMsgControlErrorPrefix, "New() a nodeList before Set().")
 		// Return directly
 		return
 	}
@@ -155,7 +157,7 @@ func (nodeList *NodeList) Get() []common.Node {
 
 	// If the local node list of this node has not been initialized
 	if len(nodeList.localNode.Addr) == 0 {
-		nodeList.println("[Control Error]:", "New() a nodeList before Get().")
+		nodeList.println(errMsgControlErrorPrefix, "New() a nodeList before Get().")
 		// Return directly
 		return nil
 	}
@@ -180,7 +182,7 @@ func (nodeList *NodeList) Publish(newMetadata []byte) {
 
 	//Return if the node's local node list has not been initialized
 	if len(nodeList.localNode.Addr) == 0 {
-		nodeList.println("[Control Error]:", "New() a nodeList before Publish().")
+		nodeList.println(errMsgControlErrorPrefix, "New() a nodeList before Publish().")
 		return
 	}
 
@@ -225,7 +227,7 @@ func (nodeList *NodeList) Read() []byte {
 
 	// If the local node list of this node has not been initialized
 	if len(nodeList.localNode.Addr) == 0 {
-		nodeList.println("[Control Error]:", "New() a nodeList before Read().")
+		nodeList.println(errMsgControlErrorPrefix, "New() a nodeList before Read().")
 		// Directly return
 		return nil
 	}
diff --git a/cmd/udp.go b/cmd/udp.go
index 731f4d1..c6b33b3 100644
--- a/cmd/udp.go
+++ b/cmd/udp.go
@@ -7,6 +7,8 @@ import (
 	"net"
 )
 
+const errMsgUDPErrorPrefix = "[UDP Error]:"
+
 // udpWrite send udp data
 func udpWrite(nodeList *NodeList, addr string, port int, data []byte) {
 	socket, err := net.DialUDP("udp", nil, &net.UDPAddr{
@@ -14,20 +16,20 @@ func udpWrite(nodeList *NodeList, addr string, port int, data []byte) {
 		Port: port,
 	})
 	if err != nil {
-		nodeList.println("[UDP Error]:", err)
+		nodeList.println(errMsgUDPErrorPrefix, err)
 		return
 	}
 
 	_, err = socket.Write(data) // socket write syscall
 	if err != nil {
-		nodeList.println("[UDP Error]:", err)
+		nodeList.println(errMsgUDPErrorPrefix, err)
 		return
 	}
 
 	defer func(socket *net.UDPConn) {
 		err = socket.Close()
 		if err != nil {
-			nodeList.println("[UDP Error]:", err)
+			nodeList.println(errMsgUDPErrorPrefix, err)
 		}
 	}(socket)
 }
@@ -37,18 +39,18 @@ func udpListen(nodeList *NodeList, mq chan []byte) {
 
 	udpAddr, err := net.ResolveUDPAddr("udp", fmt.Sprintf("%s:%d", nodeList.ListenAddr, nodeList.localNode.Port))
 	if err != nil {
-		nodeList.println("[UDP Error]:", err)
+		nodeList.println(errMsgUDPErrorPrefix, err)
 		return
 	}
 	conn, err := net.ListenUDP("udp", udpAddr)
 	if err != nil {
-		nodeList.println("[UDP Error]:", err)
+		nodeList.println(errMsgUDPErrorPrefix, err)
 		return
 	}
 	defer func(conn *net.UDPConn) {
 		err = conn.Close()
 		if err != nil {
-			nodeList.println("[UDP Error]:", err)
+			nodeList.println(errMsgUDPErrorPrefix, err)
 		}
 	}(conn)
 
@@ -59,12 +61,12 @@ func udpListen(nodeList *NodeList, mq chan []byte) {
 		// listen for UDP packets to the port
 		n, _, err := conn.ReadFromUDP(bs)
 		if err != nil {
-			nodeList.println("[UDP Error]:", err)
+			nodeList.println(errMsgUDPErrorPrefix, err)
 			continue
 		}
 
 		if n >= nodeList.Size {
-			nodeList.println("[UDP Error]:", fmt.Sprintf("received data size (%v) exceeds the limit (%v)", n, nodeList.Size))
+			nodeList.println(errMsgUDPErrorPrefix, fmt.Sprintf("received data size (%v) exceeds the limit (%v)", n, nodeList.Size))
 			continue
 		}