diff --git a/commons/pcap/pcap.go b/commons/pcap/pcap.go
index 4e7ee3a..839d9ce 100644
--- a/commons/pcap/pcap.go
+++ b/commons/pcap/pcap.go
@@ -2,6 +2,7 @@ package pcap
 
 import (
 	"sync"
+	"time"
 
 	"git.loafle.net/overflow/overflow_discovery/api/module/discovery/model"
 )
@@ -36,10 +37,13 @@ func ReleaseScanner(zone *model.Zone) {
 	defer mtx.Unlock()
 
 	if ps, ok := instances[zone.Network]; ok {
-		if ps.release() {
-			ps.stop()
-			delete(instances, zone.Network)
-		}
+		go func() {
+			time.Sleep(2 * time.Second)
+			if ps.release() {
+				ps.stop()
+				delete(instances, zone.Network)
+			}
+		}()
 	}
 }
 
diff --git a/commons/pcap/pcap_scan.go b/commons/pcap/pcap_scan.go
index 8a6fdd1..0bfc3e2 100644
--- a/commons/pcap/pcap_scan.go
+++ b/commons/pcap/pcap_scan.go
@@ -197,6 +197,7 @@ func (ps *pCapScan) release() bool {
 	if 0 > ps.refCount {
 		ps.refCount = 0
 	}
+
 	return 0 == ps.refCount
 }
 
@@ -243,6 +244,7 @@ func handleReceive(ps *pCapScan) {
 			handlePacket(ps, packet)
 		case <-ps.stopChan:
 			ps.destroy()
+			return
 		}
 	}
 }
diff --git a/discovery/ipv4/host.go b/discovery/ipv4/host.go
index 565e91f..642099b 100644
--- a/discovery/ipv4/host.go
+++ b/discovery/ipv4/host.go
@@ -15,17 +15,26 @@ import (
 )
 
 func ScanHost(zone *model.Zone, dh *model.DiscoveryHost, resultChan chan interface{}, errChan chan error, doneChan chan<- struct{}) {
+	defer func() {
+		doneChan <- struct{}{}
+	}()
+
 	ps, err := pcap.RetainScanner(zone)
 	if nil != err {
 		errChan <- fmt.Errorf("Discovery: Cannot retain pcap instance %v", err)
-		// doneChan <- struct{}{}
 		return
 	}
+
+	defer func() {
+		pcap.ReleaseScanner(zone)
+	}()
+
 	cr, err := cidr.NewCIDRRanger(zone.Network)
 	if nil != err {
 		errChan <- err
 		return
 	}
+
 	hostRanges, err := getTargetHostRange(dh, cr)
 	if nil != err {
 		errChan <- err
@@ -34,11 +43,7 @@ func ScanHost(zone *model.Zone, dh *model.DiscoveryHost, resultChan chan interfa
 
 	arpChan := ps.OpenARP()
 	defer func() {
-		if nil != ps {
-			ps.CloseARP(arpChan)
-			pcap.ReleaseScanner(zone)
-		}
-		doneChan <- struct{}{}
+		ps.CloseARP(arpChan)
 	}()
 
 	go func() {