diff --git a/tcp/dialer.go b/tcp/dialer.go
new file mode 100644
index 00000000..d2ae53f4
--- /dev/null
+++ b/tcp/dialer.go
@@ -0,0 +1,50 @@
+package tcp
+
+import (
+	"crypto/tls"
+	"net"
+	"time"
+)
+
+// NewDialer returns an initialized Dialer
+func NewDialer(header byte, remoteEncrypted, skipVerify bool) *Dialer {
+	return &Dialer{
+		header:          header,
+		remoteEncrypted: remoteEncrypted,
+		skipVerify:      skipVerify,
+	}
+}
+
+// Dialer supports dialing a cluster service.
+type Dialer struct {
+	header          byte
+	remoteEncrypted bool
+	skipVerify      bool
+}
+
+// Dial dials the cluster service at the given addr and returns a connection.
+func (d *Dialer) Dial(addr string, timeout time.Duration) (net.Conn, error) {
+	dialer := &net.Dialer{Timeout: timeout}
+
+	var err error
+	var conn net.Conn
+	if d.remoteEncrypted {
+		conf := &tls.Config{
+			InsecureSkipVerify: d.skipVerify,
+		}
+		conn, err = tls.DialWithDialer(dialer, "tcp", addr, conf)
+	} else {
+		conn, err = dialer.Dial("tcp", addr)
+	}
+	if err != nil {
+		return nil, err
+	}
+
+	// Write a marker byte to indicate message type.
+	_, err = conn.Write([]byte{d.header})
+	if err != nil {
+		conn.Close()
+		return nil, err
+	}
+	return conn, err
+}
diff --git a/tcp/dialer_test.go b/tcp/dialer_test.go
new file mode 100644
index 00000000..a703075c
--- /dev/null
+++ b/tcp/dialer_test.go
@@ -0,0 +1,86 @@
+package tcp
+
+import (
+	"net"
+	"testing"
+	"time"
+)
+
+func Test_NewDialer(t *testing.T) {
+	d := NewDialer(1, false, false)
+	if d == nil {
+		t.Fatal("failed to create a dialer")
+	}
+}
+
+func Test_DialerNoConnect(t *testing.T) {
+	d := NewDialer(87, false, false)
+	_, err := d.Dial("127.0.0.1:0", 5*time.Second)
+	if err == nil {
+		t.Fatalf("no error connecting to bad address")
+	}
+}
+
+func Test_DialerHeader(t *testing.T) {
+	s := mustNewEchoServer()
+	defer s.Close()
+
+	go s.MustStart()
+
+	d := NewDialer(87, false, false)
+	conn, err := d.Dial(s.Addr(), 10*time.Second)
+	if err != nil {
+		t.Fatalf("failed to dial echo server: %s", err.Error())
+	}
+
+	buf := make([]byte, 1)
+	_, err = conn.Read(buf)
+	if err != nil {
+		t.Fatalf("failed to read from echo server: %s", err.Error())
+	}
+	if exp, got := buf[0], byte(87); exp != got {
+		t.Fatalf("got wrong response from echo server, exp %d, got %d", exp, got)
+	}
+}
+
+type echoSever struct {
+	ln net.Listener
+}
+
+// Addr returns the address of the echo server.
+func (e *echoSever) Addr() string {
+	return e.ln.Addr().String()
+}
+
+// MustStart starts the echo server.
+func (e *echoSever) MustStart() {
+	for {
+		conn, err := e.ln.Accept()
+		if err != nil {
+			return
+		}
+		go func(c net.Conn) {
+			buf := make([]byte, 1)
+			_, err := c.Read(buf)
+			if err != nil {
+				panic("failed to read byte")
+			}
+			_, err = c.Write(buf)
+			if err != nil {
+				panic("failed to echo received byte")
+			}
+			c.Close()
+		}(conn)
+	}
+}
+
+// Close closes the echo server.
+func (e *echoSever) Close() {
+	e.ln.Close()
+}
+
+func mustNewEchoServer() *echoSever {
+	return &echoSever{
+		ln: mustTCPListener("127.0.0.1:0"),
+	}
+}
diff --git a/tcp/mux.go b/tcp/mux.go
index b2dfada2..08428a79 100644
--- a/tcp/mux.go
+++ b/tcp/mux.go
@@ -35,49 +35,6 @@ func init() {
 	stats.Add(numUnregisteredHandlers, 0)
 }
 
-// NewDialer returns an initialized Dialer
-func NewDialer(header byte, remoteEncrypted, skipVerify bool) *Dialer {
-	return &Dialer{
-		header:          header,
-		remoteEncrypted: remoteEncrypted,
-		skipVerify:      skipVerify,
-	}
-}
-
-// Dialer supports dialing a cluster service.
-type Dialer struct {
-	header          byte
-	remoteEncrypted bool
-	skipVerify      bool
-}
-
-// Dial dials the cluster service a the given addr and returns a connection.
-func (d *Dialer) Dial(addr string, timeout time.Duration) (net.Conn, error) {
-	dialer := &net.Dialer{Timeout: timeout}
-
-	var err error
-	var conn net.Conn
-	if d.remoteEncrypted {
-		conf := &tls.Config{
-			InsecureSkipVerify: d.skipVerify,
-		}
-		conn, err = tls.DialWithDialer(dialer, "tcp", addr, conf)
-	} else {
-		conn, err = dialer.Dial("tcp", addr)
-	}
-	if err != nil {
-		return nil, err
-	}
-
-	// Write a marker byte to indicate message type.
-	_, err = conn.Write([]byte{d.header})
-	if err != nil {
-		conn.Close()
-		return nil, err
-	}
-	return conn, err
-}
-
 // Layer represents the connection between nodes. It can be both used to
 // make connections to other nodes, and receive connections from other
 // nodes.