diff --git a/relay/client/client.go b/relay/client/client.go
index 1ba815018..6b8dac9df 100644
--- a/relay/client/client.go
+++ b/relay/client/client.go
@@ -371,7 +371,11 @@ func (c *Client) writeTo(id string, dstID []byte, payload []byte) (int, error) {
 			return 0, io.EOF
 		}
 	*/
-	msg := messages.MarshalTransportMsg(dstID, payload)
+	msg, err := messages.MarshalTransportMsg(dstID, payload)
+	if err != nil {
+		log.Errorf("failed to marshal transport message: %s", err)
+		return 0, err
+	}
 	n, err := c.relayConn.Write(msg)
 	if err != nil {
 		log.Errorf("failed to write transport message: %s", err)
diff --git a/relay/client/manager.go b/relay/client/manager.go
index ae44be4b9..42cbcd280 100644
--- a/relay/client/manager.go
+++ b/relay/client/manager.go
@@ -194,6 +194,7 @@ func (m *Manager) isForeignServer(address string) (bool, error) {
 	if err != nil {
 		return false, fmt.Errorf("relay client not connected")
 	}
+	log.Debugf("check if foreign server: %s != %s", rAddr.String(), address)
 	return rAddr.String() != address, nil
 }
 
diff --git a/relay/messages/id.go b/relay/messages/id.go
index c2248fb2b..dbb49cc58 100644
--- a/relay/messages/id.go
+++ b/relay/messages/id.go
@@ -3,18 +3,25 @@ package messages
 import (
 	"crypto/sha256"
 	"encoding/base64"
+	"fmt"
 )
 
 const (
-	IDSize = sha256.Size
+	prefixLength = 4
+	IDSize       = sha256.Size + 4 // 4 is equal with len(prefix)
+)
+
+var (
+	prefix = []byte("sha-") // 4 bytes
 )
 
 func HashID(peerID string) ([]byte, string) {
 	idHash := sha256.Sum256([]byte(peerID))
-	idHashString := base64.StdEncoding.EncodeToString(idHash[:])
-	return idHash[:], idHashString
+	idHashString := string(prefix) + base64.StdEncoding.EncodeToString(idHash[:])
+	prefixedHash := append(prefix, idHash[:]...)
+	return prefixedHash, idHashString
 }
 
 func HashIDToString(idHash []byte) string {
-	return base64.StdEncoding.EncodeToString(idHash)
+	return fmt.Sprintf("%s%s", idHash[:prefixLength], base64.StdEncoding.EncodeToString(idHash[prefixLength:]))
 }
diff --git a/relay/messages/id_test.go b/relay/messages/id_test.go
new file mode 100644
index 000000000..25c64955b
--- /dev/null
+++ b/relay/messages/id_test.go
@@ -0,0 +1,26 @@
+package messages
+
+import (
+	"encoding/binary"
+	"testing"
+
+	log "github.com/sirupsen/logrus"
+)
+
+func TestHashID(t *testing.T) {
+	hashedID, hashedStringId := HashID("abc")
+	enc := HashIDToString(hashedID)
+	if enc != hashedStringId {
+		t.Errorf("expected %s, got %s", hashedStringId, enc)
+	}
+
+	var magicHeader uint32 = 0x2112A442 // size 4 byte
+
+	msg := make([]byte, 4)
+	binary.BigEndian.PutUint32(msg, magicHeader)
+
+	magicHeader2 := []byte{0x21, 0x12, 0xA4, 0x42}
+
+	log.Infof("msg: %v, %v", msg, magicHeader2)
+
+}
diff --git a/relay/messages/message.go b/relay/messages/message.go
index b865687ce..92b8bced7 100644
--- a/relay/messages/message.go
+++ b/relay/messages/message.go
@@ -1,6 +1,7 @@
 package messages
 
 import (
+	"bytes"
 	"fmt"
 
 	log "github.com/sirupsen/logrus"
@@ -11,10 +12,15 @@ const (
 	MsgTypeHelloResponse MsgType = 1
 	MsgTypeTransport     MsgType = 2
 	MsgClose             MsgType = 3
+
+	headerSizeTransport = 1 + IDSize     // 1 byte for msg type, IDSize for peerID
+	headerSizeHello     = 1 + 4 + IDSize // 1 byte for msg type, 4 byte for magic header, IDSize for peerID
 )
 
 var (
 	ErrInvalidMessageLength = fmt.Errorf("invalid message length")
+
+	magicHeader = []byte{0x21, 0x12, 0xA4, 0x42}
 )
 
 type MsgType byte
@@ -35,7 +41,6 @@ func (m MsgType) String() string {
 }
 
 func DetermineClientMsgType(msg []byte) (MsgType, error) {
-	// todo: validate magic byte
 	msgType := MsgType(msg[0])
 	switch msgType {
 	case MsgTypeHello:
@@ -50,7 +55,6 @@ func DetermineClientMsgType(msg []byte) (MsgType, error) {
 }
 
 func DetermineServerMsgType(msg []byte) (MsgType, error) {
-	// todo: validate magic byte
 	msgType := MsgType(msg[0])
 	switch msgType {
 	case MsgTypeHelloResponse:
@@ -67,19 +71,21 @@ func DetermineServerMsgType(msg []byte) (MsgType, error) {
 // MarshalHelloMsg initial hello message
 func MarshalHelloMsg(peerID []byte) ([]byte, error) {
 	if len(peerID) != IDSize {
-		return nil, fmt.Errorf("invalid peerID length")
+		return nil, fmt.Errorf("invalid peerID length: %d", len(peerID))
 	}
-	msg := make([]byte, 1, 1+len(peerID))
+	msg := make([]byte, 5, headerSizeHello)
 	msg[0] = byte(MsgTypeHello)
+	copy(msg[1:5], magicHeader)
 	msg = append(msg, peerID...)
 	return msg, nil
 }
 
 func UnmarshalHelloMsg(msg []byte) ([]byte, error) {
-	if len(msg) < 2 {
+	if len(msg) < headerSizeHello {
 		return nil, fmt.Errorf("invalid 'hello' messge")
 	}
-	return msg[1:], nil
+	bytes.Equal(msg[1:5], magicHeader)
+	return msg[5:], nil
 }
 
 func MarshalHelloResponse() []byte {
@@ -98,34 +104,32 @@ func MarshalCloseMsg() []byte {
 
 // Transport message
 
-func MarshalTransportMsg(peerID []byte, payload []byte) []byte {
+func MarshalTransportMsg(peerID []byte, payload []byte) ([]byte, error) {
 	if len(peerID) != IDSize {
-		return nil
+		return nil, fmt.Errorf("invalid peerID length: %d", len(peerID))
 	}
 
-	msg := make([]byte, 1+IDSize, 1+IDSize+len(payload))
+	msg := make([]byte, headerSizeTransport, headerSizeTransport+len(payload))
 	msg[0] = byte(MsgTypeTransport)
 	copy(msg[1:], peerID)
 	msg = append(msg, payload...)
-	return msg
+	return msg, nil
 }
 
 func UnmarshalTransportMsg(buf []byte) ([]byte, []byte, error) {
-	headerSize := 1 + IDSize
-	if len(buf) < headerSize {
+	if len(buf) < headerSizeTransport {
 		return nil, nil, ErrInvalidMessageLength
 	}
 
-	return buf[1:headerSize], buf[headerSize:], nil
+	return buf[1:headerSizeTransport], buf[headerSizeTransport:], nil
 }
 
 func UnmarshalTransportID(buf []byte) ([]byte, error) {
-	headerSize := 1 + IDSize
-	if len(buf) < headerSize {
-		log.Debugf("invalid message length: %d, expected: %d, %x", len(buf), headerSize, buf)
+	if len(buf) < headerSizeTransport {
+		log.Debugf("invalid message length: %d, expected: %d, %x", len(buf), headerSizeTransport, buf)
 		return nil, ErrInvalidMessageLength
 	}
-	return buf[1:headerSize], nil
+	return buf[1:headerSizeTransport], nil
 }
 
 func UpdateTransportMsg(msg []byte, peerID []byte) error {
diff --git a/relay/messages/message_test.go b/relay/messages/message_test.go
new file mode 100644
index 000000000..d40963d8b
--- /dev/null
+++ b/relay/messages/message_test.go
@@ -0,0 +1,43 @@
+package messages
+
+import (
+	"testing"
+)
+
+func TestMarshalHelloMsg(t *testing.T) {
+	peerID := []byte("abdFAaBcawquEiCMzAabYosuUaGLtSNhKxz+")
+	bHello, err := MarshalHelloMsg(peerID)
+	if err != nil {
+		t.Fatalf("error: %v", err)
+	}
+
+	receivedPeerID, err := UnmarshalHelloMsg(bHello)
+	if err != nil {
+		t.Fatalf("error: %v", err)
+	}
+	if string(receivedPeerID) != string(peerID) {
+		t.Errorf("expected %s, got %s", peerID, receivedPeerID)
+	}
+}
+
+func TestMarshalTransportMsg(t *testing.T) {
+	peerID := []byte("abdFAaBcawquEiCMzAabYosuUaGLtSNhKxz+")
+	payload := []byte("payload")
+	msg, err := MarshalTransportMsg(peerID, payload)
+	if err != nil {
+		t.Fatalf("error: %v", err)
+	}
+
+	id, respPayload, err := UnmarshalTransportMsg(msg)
+	if err != nil {
+		t.Fatalf("error: %v", err)
+	}
+
+	if string(id) != string(peerID) {
+		t.Errorf("expected %s, got %s", peerID, id)
+	}
+
+	if string(respPayload) != string(payload) {
+		t.Errorf("expected %s, got %s", payload, respPayload)
+	}
+}