diff --git a/README.md b/README.md
index ddfd2be..0dd9b34 100644
--- a/README.md
+++ b/README.md
@@ -1,4 +1,4 @@
-# Reality - Tls - Scanner
+# Reality - TLS - Scanner
 
 Build
 ```
@@ -10,5 +10,5 @@ Usage
 Recommend to run this tool locally. It may cause VPS to be flagged if you run scanner in the cloud.
 ```
 ./RealiTLScanner -addr www.microsoft.com
-./RealiTLScanner -addr 20.81.111.85
-``
+./RealiTLScanner -addr 20.81.111.85 -thread 10
+```
diff --git a/main.go b/main.go
index 037e7c3..51b6fcf 100644
--- a/main.go
+++ b/main.go
@@ -4,38 +4,49 @@ import (
 	"crypto/tls"
 	"flag"
 	"fmt"
+	"math/big"
 	"net"
+	"sync"
 	"time"
 )
 
 func main() {
 	addrPtr := flag.String("addr", "127.0.0.1", "Destination to start scan")
 	portPtr := flag.String("port", "443", "Port to scan")
+	threadPtr := flag.Int("thread", 2, "Number of threads to scan in parallel")
 	flag.Parse()
-	fmt.Println("Reality Tls Scanner running: ", *addrPtr, ":", *portPtr)
+	fmt.Println("Reality TLS Scanner running: ", *addrPtr, ":", *portPtr)
 	s := Scanner {
 		addr: *addrPtr,
 		port: *portPtr,
 		timeout: 10 * time.Second,
-		numberOfThread: 1,
+		numberOfThread: *threadPtr,
+		mu: new(sync.Mutex),
 	}
 	s.Run()
 }
 
 type Scanner struct {
-	addr string
-	port string
-	timeout time.Duration
+	addr           string
+	port           string
+	timeout        time.Duration
 	numberOfThread int
+	mu             *sync.Mutex
+	high		   net.IP
+	low			   net.IP
 }
 
-func (s Scanner) Run() {
+func (s *Scanner) Run() {
 	conn, err := net.DialTimeout("tcp", s.addr+":"+s.port, s.timeout)
 	if err != nil {
 		fmt.Println("Dial failed: ", err)
 		return
 	}
 	line := "" + conn.RemoteAddr().String() + " \t----- "
+	s.mu.Lock()
+	s.high = conn.RemoteAddr().(*net.TCPAddr).IP
+	s.low = conn.RemoteAddr().(*net.TCPAddr).IP
+	s.mu.Unlock()
 	conn.SetDeadline(time.Now().Add(s.timeout))
 	c := tls.Client(conn, &tls.Config {
 		InsecureSkipVerify: true,
@@ -44,11 +55,65 @@ func (s Scanner) Run() {
 	err = c.Handshake()
 	if err != nil {
 		fmt.Println("", line, "TLS handshake failed: ", err)
-		return
+	} else {
+		defer c.Close()
+		state := c.ConnectionState()
+		fmt.Println("", line, "Found TLS v", TlsDic[state.Version], "\tALPN", state.NegotiatedProtocol, "\t", state.PeerCertificates[0].Subject)
 	}
-	defer c.Close()
-	state := c.ConnectionState()
-	fmt.Println("", line, "Found TLS v", TlsDic[state.Version], "\tALPN", state.NegotiatedProtocol, "\t", state.PeerCertificates[0].Subject)
+	for i := 0; i < s.numberOfThread; i++ {
+		go s.Scan(i % 2 == 0)
+	}
+	for {
+		// now the scans are performed in goroutines
+	}
+}
+
+func (s *Scanner) Scan(increment bool) {
+	var addr string
+	s.mu.Lock()
+	if increment {
+		s.high = nextIP(s.high, increment)
+		addr = s.high.String()
+	} else {
+		s.low = nextIP(s.low, increment)
+		addr = s.low.String()
+	}
+	s.mu.Unlock()
+	conn, err := net.DialTimeout("tcp", addr+":"+s.port, s.timeout)
+	if err != nil {
+		fmt.Println("Dial failed: ", err)
+	} else {
+		line := "" + conn.RemoteAddr().String() + " \t----- "
+		conn.SetDeadline(time.Now().Add(s.timeout))
+		c := tls.Client(conn, &tls.Config {
+			InsecureSkipVerify: true,
+			NextProtos: []string{"h2", "http/1.1"},
+		})
+		err = c.Handshake()
+		if err != nil {
+			fmt.Println("", line, "TLS handshake failed: ", err)
+		} else {
+			defer c.Close()
+			state := c.ConnectionState()
+			fmt.Println("", line, "Found TLS v", TlsDic[state.Version], "\tALPN", state.NegotiatedProtocol, "\t", state.PeerCertificates[0].Subject)
+		}
+	}
+	go s.Scan(increment)
+}
+
+func nextIP(ip net.IP, increment bool) net.IP {
+    // Convert to big.Int and increment
+    ipb := big.NewInt(0).SetBytes([]byte(ip))
+	if increment {
+		ipb.Add(ipb, big.NewInt(1))
+	} else {
+		ipb.Sub(ipb, big.NewInt(1))
+	}
+
+    // Add leading zeros
+    b := ipb.Bytes()
+    b = append(make([]byte, len(ip)-len(b)), b...)
+    return net.IP(b)
 }
 
 var TlsDic = map[uint16]string{