diff --git a/main.go b/main.go
index 8345596..eb8af96 100644
--- a/main.go
+++ b/main.go
@@ -31,7 +31,7 @@ func main() {
 	flag.StringVar(&in, "in", "", "Specify a file that contains multiple "+
 		"IPs, IP CIDRs or domains to scan, divided by line break")
 	flag.IntVar(&port, "port", 443, "Specify a HTTPS port to check")
-	flag.IntVar(&thread, "thread", 1, "Count of concurrent tasks")
+	flag.IntVar(&thread, "thread", 2, "Count of concurrent tasks")
 	flag.StringVar(&out, "out", "out.csv", "Output file to store the result")
 	flag.IntVar(&timeout, "timeout", 10, "Timeout for every check")
 	flag.BoolVar(&verbose, "v", false, "Verbose output")
@@ -39,6 +39,10 @@ func main() {
 	flag.StringVar(&url, "url", "", "Crawl the domain list from a URL, "+
 		"e.g. https://launchpad.net/ubuntu/+archivemirrors")
 	flag.Parse()
+	s := Scanner{
+		mu: new(sync.Mutex),
+	}
+
 	if verbose {
 		slog.SetDefault(slog.New(slog.NewTextHandler(os.Stdout, &slog.HandlerOptions{
 			Level: slog.LevelDebug,
@@ -66,7 +70,7 @@ func main() {
 	}
 	var hostChan <-chan Host
 	if addr != "" {
-		hostChan = Iterate(strings.NewReader(addr))
+		hostChan = Iterate(strings.NewReader(addr), true)
 	} else if in != "" {
 		f, err := os.Open(in)
 		if err != nil {
@@ -74,7 +78,7 @@ func main() {
 			return
 		}
 		defer f.Close()
-		hostChan = Iterate(f)
+		hostChan = Iterate(f, false)
 	} else {
 		slog.Info("Fetching url...")
 		resp, err := http.Get(url)
@@ -95,7 +99,7 @@ func main() {
 		}
 		domains = RemoveDuplicateStr(domains)
 		slog.Info("Parsed domains", "count", len(domains))
-		hostChan = Iterate(strings.NewReader(strings.Join(domains, "\n")))
+		hostChan = Iterate(strings.NewReader(strings.Join(domains, "\n")), len(domains) <= 1)
 	}
 	outCh := OutWriter(outWriter)
 	defer close(outCh)
@@ -104,7 +108,13 @@ func main() {
 	for i := 0; i < thread; i++ {
 		go func() {
 			for ip := range hostChan {
-				ScanTLS(ip, outCh)
+				s.Scan(ip, outCh, true)
+				if ip.Infinity { // only one ip
+					for i := 0; i < thread - 1; i++ {
+						go s.Scan(ip, outCh, i%2 == 1)
+					}
+					for {}
+				}
 			}
 			wg.Done()
 		}()
diff --git a/scanner.go b/scanner.go
index fdb4054..40cda96 100644
--- a/scanner.go
+++ b/scanner.go
@@ -3,13 +3,44 @@ package main
 import (
 	"crypto/tls"
 	"log/slog"
+	"math/big"
 	"net"
 	"strconv"
 	"strings"
+	"sync"
 	"time"
 )
 
-func ScanTLS(host Host, out chan<- string) {
+type Scanner struct {
+	mu   *sync.Mutex
+	high net.IP
+	low  net.IP
+}
+
+func (s *Scanner) Scan(host Host, out chan<- string, increment bool) {
+	if host.Infinity && host.IP != nil {
+		s.mu.Lock()
+		if s.high == nil {
+			s.high = host.IP
+			s.low = host.IP
+			host.Origin = ""
+			host.Type = HostTypeIP
+		} else if increment {
+			s.high = nextIP(s.high, increment)
+			host.IP = s.high
+		} else {
+			s.low = nextIP(s.low, increment)
+			host.IP = s.low
+		}
+		s.mu.Unlock()
+	}
+	ScanTLS(host, out, increment)
+	if host.Infinity && host.IP != nil {
+		go s.Scan(host, out, increment)
+	}
+}
+
+func ScanTLS(host Host, out chan<- string, increment bool) {
 	if host.IP == nil {
 		ips, err := net.LookupIP(host.Origin)
 		if err != nil {
@@ -71,3 +102,18 @@ func ScanTLS(host Host, out chan<- string) {
 		"origin", host.Origin,
 		"tls", tls.VersionName(state.Version), "alpn", alpn, "cert-domain", domain, "cert-issuer", issuers)
 }
+
+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)
+}
diff --git a/utils.go b/utils.go
index 913d63b..8b80797 100644
--- a/utils.go
+++ b/utils.go
@@ -21,12 +21,13 @@ const (
 type HostType int
 
 type Host struct {
-	IP     net.IP
-	Origin string
-	Type   HostType
+	IP       net.IP
+	Origin   string
+	Type     HostType
+	Infinity bool
 }
 
-func Iterate(reader io.Reader) <-chan Host {
+func Iterate(reader io.Reader, infinity bool) <-chan Host {
 	scanner := bufio.NewScanner(reader)
 	hostChan := make(chan Host)
 	go func() {
@@ -40,9 +41,10 @@ func Iterate(reader io.Reader) <-chan Host {
 			if ip != nil && (ip.To4() != nil || enableIPv6) {
 				// ip address
 				hostChan <- Host{
-					IP:     ip,
-					Origin: line,
-					Type:   HostTypeIP,
+					IP:       ip,
+					Origin:   line,
+					Type:     HostTypeIP,
+					Infinity: infinity,
 				}
 				continue
 			}
@@ -65,9 +67,10 @@ func Iterate(reader io.Reader) <-chan Host {
 					ip = net.ParseIP(addr.String())
 					if ip != nil {
 						hostChan <- Host{
-							IP:     ip,
-							Origin: line,
-							Type:   HostTypeCIDR,
+							IP:       ip,
+							Origin:   line,
+							Type:     HostTypeCIDR,
+							Infinity: false,
 						}
 					}
 					addr = addr.Next()
@@ -77,9 +80,10 @@ func Iterate(reader io.Reader) <-chan Host {
 			if ValidateDomainName(line) {
 				// domain
 				hostChan <- Host{
-					IP:     nil,
-					Origin: line,
-					Type:   HostTypeDomain,
+					IP:       nil,
+					Origin:   line,
+					Type:     HostTypeDomain,
+					Infinity: infinity,
 				}
 				continue
 			}