diff --git a/cmd/gid.go b/cmd/gid.go
deleted file mode 100644
index f0a89b2..0000000
--- a/cmd/gid.go
+++ /dev/null
@@ -1,92 +0,0 @@
-package main
-
-import (
-	"bytes"
-	"encoding/binary"
-	"fmt"
-	"net"
-	"os"
-
-	"github.com/satta/gommunityid"
-
-	"github.com/google/gopacket"
-	"github.com/google/gopacket/layers"
-	"github.com/google/gopacket/pcap"
-)
-
-func tupleLessThan(addr1, addr2 []byte, port1, port2 uint16) bool {
-	return bytes.Compare(addr1, addr2) == -1 || (bytes.Equal(addr1, addr2) && port1 < port2)
-}
-
-func main() {
-	cid := gommunityid.CommunityIDv1{
-		Seed: 0,
-	}
-	if handle, err := pcap.OpenOffline(os.Args[1]); err != nil {
-		panic(err)
-	} else {
-		packetSource := gopacket.NewPacketSource(handle, handle.LinkType())
-		for packet := range packetSource.Packets() {
-			var netLayer gopacket.NetworkLayer
-			if netLayer = packet.NetworkLayer(); netLayer == nil {
-				continue
-			}
-			var proto uint8
-			switch netLayer.LayerType() {
-			case layers.LayerTypeIPv4:
-				proto = uint8(netLayer.(*layers.IPv4).Protocol)
-			case layers.LayerTypeIPv6:
-				proto = uint8(netLayer.(*layers.IPv6).NextLayerType())
-			case layers.LayerTypeICMPv4:
-				proto = 1
-			case layers.LayerTypeICMPv6:
-				proto = 58
-			}
-			src, dst := netLayer.NetworkFlow().Endpoints()
-
-			ft := gommunityid.FlowTuple{
-				Proto: proto,
-				Srcip: net.IP(src.Raw()),
-				Dstip: net.IP(dst.Raw()),
-			}
-
-			var transLayer gopacket.TransportLayer
-			var srcP, dstP uint16
-			if transLayer = packet.TransportLayer(); transLayer == nil {
-				if got, ok := packet.Layer(layers.LayerTypeICMPv6).(*layers.ICMPv6); ok {
-					var oneway bool
-					srcP, dstP, oneway = gommunityid.GetICMPv6PortEquivalents(got.TypeCode.Type(), got.TypeCode.Code())
-					ft.Srcport, ft.Dstport = srcP, dstP
-					if !oneway && !tupleLessThan(ft.Srcip, ft.Dstip, ft.Srcport, ft.Dstport) {
-						ft.Srcip, ft.Dstip, ft.Srcport, ft.Dstport = ft.Dstip, ft.Srcip, ft.Dstport, ft.Srcport
-					}
-
-				}
-				if got, ok := packet.Layer(layers.LayerTypeICMPv4).(*layers.ICMPv4); ok {
-					var oneway bool
-					srcP, dstP, oneway = gommunityid.GetICMPv4PortEquivalents(got.TypeCode.Type(), got.TypeCode.Code())
-					ft.Srcport, ft.Dstport = srcP, dstP
-					if !oneway && !tupleLessThan(ft.Srcip, ft.Dstip, ft.Srcport, ft.Dstport) {
-						ft.Srcip, ft.Dstip, ft.Srcport, ft.Dstport = ft.Dstip, ft.Srcip, ft.Dstport, ft.Srcport
-					}
-				}
-			} else {
-				_srcP, _dstP := transLayer.TransportFlow().Endpoints()
-				srcP, dstP = binary.BigEndian.Uint16(_srcP.Raw()), binary.BigEndian.Uint16(_dstP.Raw())
-				ft.Srcport, ft.Dstport = srcP, dstP
-				if !tupleLessThan(ft.Srcip, ft.Dstip, ft.Srcport, ft.Dstport) {
-					ft.Srcip, ft.Dstip, ft.Srcport, ft.Dstport = ft.Dstip, ft.Srcip, ft.Dstport, ft.Srcport
-				}
-			}
-
-			communityid := cid.CalcBase64(ft)
-			fmt.Printf("%d%s | %s | %s %s %d %d %d\n",
-				packet.Metadata().Timestamp.Unix(),
-				packet.Metadata().Timestamp.Format(".000000"),
-				communityid,
-				src, dst,
-				proto,
-				srcP, dstP)
-		}
-	}
-}
diff --git a/cmd/gommunityid.go b/cmd/gommunityid.go
new file mode 100644
index 0000000..1818dc0
--- /dev/null
+++ b/cmd/gommunityid.go
@@ -0,0 +1,60 @@
+package main
+
+import (
+	"flag"
+	"fmt"
+	"log"
+	"os"
+
+	"github.com/satta/gommunityid"
+)
+
+func main() {
+
+	pcapCmd := flag.NewFlagSet("pcap", flag.ExitOnError)
+	pcapVersion := pcapCmd.Uint("version", 1, "Community ID version")
+	pcapSeed := pcapCmd.Uint("seed", 0, "seed value (default 0)")
+
+	tupleCmd := flag.NewFlagSet("tuple", flag.ExitOnError)
+	tupleVersion := tupleCmd.Uint("version", 1, "Community ID version")
+	tupleSeed := tupleCmd.Uint("seed", 0, "seed value (default 0)")
+
+	if len(os.Args) < 2 {
+		fmt.Println("expected 'pcap' or 'tuple' subcommands")
+		os.Exit(1)
+	}
+	switch os.Args[1] {
+	case "pcap":
+		pcapCmd.Parse(os.Args[2:])
+		if len(pcapCmd.Args()) == 0 {
+			log.Println("No input file given")
+			flag.PrintDefaults()
+			os.Exit(0)
+		}
+		ftChan, err := gommunityid.PcapFlowTupleSource(pcapCmd.Args()[0])
+		if err != nil {
+			log.Fatal(err)
+		}
+		cid, err := gommunityid.GetCommunityIDByVersion(*pcapVersion, uint16(*pcapSeed))
+		if err != nil {
+			log.Fatal(err)
+		}
+		for ft := range ftChan {
+			communityid := cid.CalcBase64(ft.FlowTuple)
+			fmt.Printf("%d%s | %s | %s %s %d %d %d\n",
+				ft.Metadata.Timestamp.Unix(),
+				ft.Metadata.Timestamp.Format(".000000"),
+				communityid,
+				ft.FlowTuple.Srcip, ft.FlowTuple.Dstip,
+				ft.FlowTuple.Proto,
+				ft.FlowTuple.Srcport, ft.FlowTuple.Dstport)
+		}
+	case "tuple":
+		tupleCmd.Parse(os.Args[2:])
+		fmt.Printf("not yet implemented")
+		_, _ = tupleSeed, tupleVersion
+	default:
+		fmt.Println("expected 'pcap' or 'tuple' subcommands")
+		os.Exit(1)
+	}
+}