func tryCapture(iface net.Interface) error {
if iface.Name[:2] == "lo" {
return fmt.Errorf("skipping loopback")
}
var h *pcap.Handle
var err error
switch *mode {
case "basic":
h, err = pcap.OpenLive(iface.Name, 65536, false, time.Second*3)
if err != nil {
return fmt.Errorf("openlive: %v", err)
}
defer h.Close()
case "filtered":
h, err = pcap.OpenLive(iface.Name, 65536, false, time.Second*3)
if err != nil {
return fmt.Errorf("openlive: %v", err)
}
defer h.Close()
if err := h.SetBPFFilter("port 80 or port 443"); err != nil {
return fmt.Errorf("setbpf: %v", err)
}
case "timestamp":
u, err := pcap.NewInactiveHandle(iface.Name)
if err != nil {
return err
}
defer u.CleanUp()
if err = u.SetSnapLen(65536); err != nil {
return err
} else if err = u.SetPromisc(false); err != nil {
return err
} else if err = u.SetTimeout(time.Second * 3); err != nil {
return err
}
sources := u.SupportedTimestamps()
if len(sources) == 0 {
return fmt.Errorf("no supported timestamp sources")
} else if err := u.SetTimestampSource(sources[0]); err != nil {
return fmt.Errorf("settimestampsource(%v): %v", sources[0], err)
} else if h, err = u.Activate(); err != nil {
return fmt.Errorf("could not activate: %v", err)
}
defer h.Close()
default:
panic("Invalid --mode: " + *mode)
}
go generatePackets()
h.ReadPacketData() // Do one dummy read to clear any timeouts.
data, ci, err := h.ReadPacketData()
if err != nil {
return fmt.Errorf("readpacketdata: %v", err)
}
log.Printf("Read packet, %v bytes, CI: %+v", len(data), ci)
return nil
}
// newScanner creates a new scanner for a given destination IP address, using
// router to determine how to route packets to that IP.
func newScanner(ip net.IP, router routing.Router) (*scanner, error) {
s := &scanner{
dst: ip,
opts: gopacket.SerializeOptions{
FixLengths: true,
ComputeChecksums: true,
},
buf: gopacket.NewSerializeBuffer(),
}
// Figure out the route to the IP.
iface, gw, src, err := router.Route(ip)
if err != nil {
return nil, err
}
log.Printf("scanning ip %v with interface %v, gateway %v, src %v", ip, iface.Name, gw, src)
s.gw, s.src, s.iface = gw, src, iface
// Open the handle for reading/writing.
// Note we could very easily add some BPF filtering here to greatly
// decrease the number of packets we have to look at when getting back
// scan results.
handle, err := pcap.OpenLive(iface.Name, 65536, true, pcap.BlockForever)
if err != nil {
return nil, err
}
s.handle = handle
return s, nil
}
func main() {
defer util.Run()()
var handle *pcap.Handle
var err error
// Set up pcap packet capture
if *fname != "" {
log.Printf("Reading from pcap dump %q", *fname)
handle, err = pcap.OpenOffline(*fname)
} else {
log.Printf("Starting capture on interface %q", *iface)
handle, err = pcap.OpenLive(*iface, int32(*snaplen), true, pcap.BlockForever)
}
if err != nil {
log.Fatal(err)
}
if err := handle.SetBPFFilter(*filter); err != nil {
log.Fatal(err)
}
// Set up assembly
streamFactory := &httpStreamFactory{}
streamPool := tcpassembly.NewStreamPool(streamFactory)
assembler := tcpassembly.NewAssembler(streamPool)
log.Println("reading in packets")
// Read in packets, pass to assembler.
packetSource := gopacket.NewPacketSource(handle, handle.LinkType())
packets := packetSource.Packets()
ticker := time.Tick(time.Minute)
for {
select {
case packet := <-packets:
// A nil packet indicates the end of a pcap file.
if packet == nil {
return
}
if *logAllPackets {
log.Println(packet)
}
if packet.NetworkLayer() == nil || packet.TransportLayer() == nil || packet.TransportLayer().LayerType() != layers.LayerTypeTCP {
log.Println("Unusable packet")
continue
}
tcp := packet.TransportLayer().(*layers.TCP)
assembler.AssembleWithTimestamp(packet.NetworkLayer().NetworkFlow(), tcp, packet.Metadata().Timestamp)
case <-ticker:
// Every minute, flush connections that haven't seen activity in the past 2 minutes.
assembler.FlushOlderThan(time.Now().Add(time.Minute * -2))
}
}
}
// scan scans an individual interface's local network for machines using ARP requests/replies.
//
// scan loops forever, sending packets out regularly. It returns an error if
// it's ever unable to write a packet.
func scan(iface *net.Interface) error {
// We just look for IPv4 addresses, so try to find if the interface has one.
var addr *net.IPNet
if addrs, err := iface.Addrs(); err != nil {
return err
} else {
for _, a := range addrs {
if ipnet, ok := a.(*net.IPNet); ok {
if ip4 := ipnet.IP.To4(); ip4 != nil {
addr = &net.IPNet{
IP: ip4,
Mask: ipnet.Mask[len(ipnet.Mask)-4:],
}
break
}
}
}
}
// Sanity-check that the interface has a good address.
if addr == nil {
return fmt.Errorf("no good IP network found")
} else if addr.IP[0] == 127 {
return fmt.Errorf("skipping localhost")
} else if addr.Mask[0] != 0xff || addr.Mask[1] != 0xff {
return fmt.Errorf("mask means network is too large")
}
log.Printf("Using network range %v for interface %v", addr, iface.Name)
// Open up a pcap handle for packet reads/writes.
handle, err := pcap.OpenLive(iface.Name, 65536, true, pcap.BlockForever)
if err != nil {
return err
}
defer handle.Close()
// Start up a goroutine to read in packet data.
stop := make(chan struct{})
go readARP(handle, iface, stop)
defer close(stop)
for {
// Write our scan packets out to the handle.
if err := writeARP(handle, iface, addr); err != nil {
log.Printf("error writing packets on %v: %v", iface.Name, err)
return err
}
// We don't know exactly how long it'll take for packets to be
// sent back to us, but 10 seconds should be more than enough
// time ;)
time.Sleep(10 * time.Second)
}
}
func main() {
defer util.Run()()
log.Printf("starting capture on interface %q", *iface)
// Set up pcap packet capture
handle, err := pcap.OpenLive(*iface, int32(*snaplen), true, pcap.BlockForever)
if err != nil {
panic(err)
}
if err := handle.SetBPFFilter(*filter); err != nil {
panic(err)
}
// Set up assembly
streamFactory := &myFactory{bidiMap: make(map[key]*bidi)}
streamPool := tcpassembly.NewStreamPool(streamFactory)
assembler := tcpassembly.NewAssembler(streamPool)
log.Println("reading in packets")
// Read in packets, pass to assembler.
packetSource := gopacket.NewPacketSource(handle, handle.LinkType())
packets := packetSource.Packets()
ticker := time.Tick(timeout / 4)
for {
select {
case packet := <-packets:
if *logAllPackets {
log.Println(packet)
}
if packet.NetworkLayer() == nil || packet.TransportLayer() == nil || packet.TransportLayer().LayerType() != layers.LayerTypeTCP {
log.Println("Unusable packet")
continue
}
tcp := packet.TransportLayer().(*layers.TCP)
assembler.AssembleWithTimestamp(packet.NetworkLayer().NetworkFlow(), tcp, packet.Metadata().Timestamp)
case <-ticker:
// Every minute, flush connections that haven't seen activity in the past minute.
log.Println("---- FLUSHING ----")
assembler.FlushOlderThan(time.Now().Add(-timeout))
streamFactory.collectOldStreams()
}
}
}
func (sniffer *SnifferSetup) setFromConfig(config *config.InterfacesConfig) error {
var err error
sniffer.config = config
if len(sniffer.config.File) > 0 {
logp.Debug("sniffer", "Reading from file: %s", sniffer.config.File)
// we read file with the pcap provider
sniffer.config.Type = "pcap"
}
// set defaults
if len(sniffer.config.Device) == 0 {
sniffer.config.Device = "any"
}
if index, err := strconv.Atoi(sniffer.config.Device); err == nil { // Device is numeric
devices, err := ListDeviceNames()
if err != nil {
return fmt.Errorf("Error getting devices list: %v", err)
}
sniffer.config.Device, err = deviceNameFromIndex(index, devices)
if err != nil {
return fmt.Errorf("Couldn't understand device index %d: %v", index, err)
}
logp.Info("Resolved device index %d to device: %s", index, sniffer.config.Device)
}
if sniffer.config.Snaplen == 0 {
sniffer.config.Snaplen = 65535
}
if sniffer.config.Type == "autodetect" || sniffer.config.Type == "" {
sniffer.config.Type = "pcap"
}
logp.Debug("sniffer", "Sniffer type: %s device: %s", sniffer.config.Type, sniffer.config.Device)
switch sniffer.config.Type {
case "pcap":
if len(sniffer.config.File) > 0 {
sniffer.pcapHandle, err = pcap.OpenOffline(sniffer.config.File)
if err != nil {
return err
}
} else {
sniffer.pcapHandle, err = pcap.OpenLive(
sniffer.config.Device,
int32(sniffer.config.Snaplen),
true,
500*time.Millisecond)
if err != nil {
return err
}
err = sniffer.pcapHandle.SetBPFFilter(sniffer.config.Bpf_filter)
if err != nil {
return err
}
}
sniffer.DataSource = gopacket.PacketDataSource(sniffer.pcapHandle)
case "af_packet":
if sniffer.config.Buffer_size_mb == 0 {
sniffer.config.Buffer_size_mb = 24
}
frame_size, block_size, num_blocks, err := afpacketComputeSize(
sniffer.config.Buffer_size_mb,
sniffer.config.Snaplen,
os.Getpagesize())
if err != nil {
return err
}
sniffer.afpacketHandle, err = NewAfpacketHandle(
sniffer.config.Device,
frame_size,
block_size,
num_blocks,
500*time.Millisecond)
if err != nil {
return err
}
err = sniffer.afpacketHandle.SetBPFFilter(sniffer.config.Bpf_filter)
if err != nil {
return fmt.Errorf("SetBPFFilter failed: %s", err)
}
sniffer.DataSource = gopacket.PacketDataSource(sniffer.afpacketHandle)
case "pfring":
sniffer.pfringHandle, err = NewPfringHandle(
sniffer.config.Device,
sniffer.config.Snaplen,
true)
if err != nil {
return err
}
err = sniffer.pfringHandle.SetBPFFilter(sniffer.config.Bpf_filter)
if err != nil {
return fmt.Errorf("SetBPFFilter failed: %s", err)
}
err = sniffer.pfringHandle.Enable()
if err != nil {
return fmt.Errorf("Enable failed: %s", err)
}
sniffer.DataSource = gopacket.PacketDataSource(sniffer.pfringHandle)
default:
return fmt.Errorf("Unknown sniffer type: %s", sniffer.config.Type)
}
return nil
}
func main() {
defer util.Run()()
flushDuration, err := time.ParseDuration(*flushAfter)
if err != nil {
log.Fatal("invalid flush duration: ", *flushAfter)
}
log.Printf("starting capture on interface %q", *iface)
// Set up pcap packet capture
handle, err := pcap.OpenLive(*iface, int32(*snaplen), true, flushDuration/2)
if err != nil {
log.Fatal("error opening pcap handle: ", err)
}
if err := handle.SetBPFFilter(*filter); err != nil {
log.Fatal("error setting BPF filter: ", err)
}
// Set up assembly
streamFactory := &statsStreamFactory{}
streamPool := tcpassembly.NewStreamPool(streamFactory)
assembler := tcpassembly.NewAssembler(streamPool)
assembler.MaxBufferedPagesPerConnection = *bufferedPerConnection
assembler.MaxBufferedPagesTotal = *bufferedTotal
log.Println("reading in packets")
// We use a DecodingLayerParser here instead of a simpler PacketSource.
// This approach should be measurably faster, but is also more rigid.
// PacketSource will handle any known type of packet safely and easily,
// but DecodingLayerParser will only handle those packet types we
// specifically pass in. This trade-off can be quite useful, though, in
// high-throughput situations.
var eth layers.Ethernet
var dot1q layers.Dot1Q
var ip4 layers.IPv4
var ip6 layers.IPv6
var ip6extensions layers.IPv6ExtensionSkipper
var tcp layers.TCP
var payload gopacket.Payload
parser := gopacket.NewDecodingLayerParser(layers.LayerTypeEthernet,
ð, &dot1q, &ip4, &ip6, &ip6extensions, &tcp, &payload)
decoded := make([]gopacket.LayerType, 0, 4)
nextFlush := time.Now().Add(flushDuration / 2)
var byteCount int64
start := time.Now()
loop:
for ; *packetCount != 0; *packetCount-- {
// Check to see if we should flush the streams we have
// that haven't seen any new data in a while. Note we set a
// timeout on our PCAP handle, so this should happen even if we
// never see packet data.
if time.Now().After(nextFlush) {
stats, _ := handle.Stats()
log.Printf("flushing all streams that haven't seen packets in the last 2 minutes, pcap stats: %+v", stats)
assembler.FlushOlderThan(time.Now().Add(flushDuration))
nextFlush = time.Now().Add(flushDuration / 2)
}
// To speed things up, we're also using the ZeroCopy method for
// reading packet data. This method is faster than the normal
// ReadPacketData, but the returned bytes in 'data' are
// invalidated by any subsequent ZeroCopyReadPacketData call.
// Note that tcpassembly is entirely compatible with this packet
// reading method. This is another trade-off which might be
// appropriate for high-throughput sniffing: it avoids a packet
// copy, but its cost is much more careful handling of the
// resulting byte slice.
data, ci, err := handle.ZeroCopyReadPacketData()
if err != nil {
log.Printf("error getting packet: %v", err)
continue
}
err = parser.DecodeLayers(data, &decoded)
if err != nil {
log.Printf("error decoding packet: %v", err)
continue
}
if *logAllPackets {
log.Printf("decoded the following layers: %v", decoded)
}
byteCount += int64(len(data))
// Find either the IPv4 or IPv6 address to use as our network
// layer.
foundNetLayer := false
var netFlow gopacket.Flow
for _, typ := range decoded {
switch typ {
case layers.LayerTypeIPv4:
netFlow = ip4.NetworkFlow()
foundNetLayer = true
case layers.LayerTypeIPv6:
netFlow = ip6.NetworkFlow()
foundNetLayer = true
case layers.LayerTypeTCP:
if foundNetLayer {
assembler.AssembleWithTimestamp(netFlow, &tcp, ci.Timestamp)
} else {
log.Println("could not find IPv4 or IPv6 layer, inoring")
}
continue loop
}
}
log.Println("could not find TCP layer")
}
assembler.FlushAll()
log.Printf("processed %d bytes in %v", byteCount, time.Since(start))
}
func (sniffer *SnifferSetup) setFromConfig(config *config.InterfacesConfig) error {
var err error
sniffer.config = config
if len(sniffer.config.File) > 0 {
logp.Debug("sniffer", "Reading from file: %s", sniffer.config.File)
// we read file with the pcap provider
sniffer.config.Type = "pcap"
}
// set defaults
if len(sniffer.config.Device) == 0 {
sniffer.config.Device = "any"
}
if len(sniffer.config.Devices) == 0 {
// 'devices' not set but 'device' is set. For backwards compatibility,
// use the one configured device
if len(sniffer.config.Device) > 0 {
sniffer.config.Devices = []string{sniffer.config.Device}
}
}
if sniffer.config.Snaplen == 0 {
sniffer.config.Snaplen = 65535
}
if sniffer.config.Type == "autodetect" || sniffer.config.Type == "" {
sniffer.config.Type = "pcap"
}
logp.Debug("sniffer", "Sniffer type: %s devices: %s", sniffer.config.Type, sniffer.config.Devices)
switch sniffer.config.Type {
case "pcap":
if len(sniffer.config.File) > 0 {
sniffer.pcapHandle, err = pcap.OpenOffline(sniffer.config.File)
if err != nil {
return err
}
} else {
if len(sniffer.config.Devices) > 1 {
return fmt.Errorf("Pcap sniffer only supports one device. You can use 'any' if you want")
}
sniffer.pcapHandle, err = pcap.OpenLive(
sniffer.config.Devices[0],
int32(sniffer.config.Snaplen),
true,
500*time.Millisecond)
if err != nil {
return err
}
err = sniffer.pcapHandle.SetBPFFilter(sniffer.config.Bpf_filter)
if err != nil {
return err
}
}
sniffer.DataSource = gopacket.PacketDataSource(sniffer.pcapHandle)
case "af_packet":
if sniffer.config.Buffer_size_mb == 0 {
sniffer.config.Buffer_size_mb = 24
}
if len(sniffer.config.Devices) > 1 {
return fmt.Errorf("Afpacket sniffer only supports one device. You can use 'any' if you want")
}
frame_size, block_size, num_blocks, err := afpacketComputeSize(
sniffer.config.Buffer_size_mb,
sniffer.config.Snaplen,
os.Getpagesize())
if err != nil {
return err
}
sniffer.afpacketHandle, err = NewAfpacketHandle(
sniffer.config.Devices[0],
frame_size,
block_size,
num_blocks,
500*time.Millisecond)
if err != nil {
return err
}
err = sniffer.afpacketHandle.SetBPFFilter(sniffer.config.Bpf_filter)
if err != nil {
return fmt.Errorf("SetBPFFilter failed: %s", err)
}
sniffer.DataSource = gopacket.PacketDataSource(sniffer.afpacketHandle)
case "pfring":
if len(sniffer.config.Devices) > 1 {
return fmt.Errorf("Afpacket sniffer only supports one device. You can use 'any' if you want")
}
sniffer.pfringHandle, err = NewPfringHandle(
sniffer.config.Devices[0],
sniffer.config.Snaplen,
true)
if err != nil {
return err
}
err = sniffer.pfringHandle.SetBPFFilter(sniffer.config.Bpf_filter)
if err != nil {
return fmt.Errorf("SetBPFFilter failed: %s", err)
}
err = sniffer.pfringHandle.Enable()
if err != nil {
return fmt.Errorf("Enable failed: %s", err)
}
sniffer.DataSource = gopacket.PacketDataSource(sniffer.pfringHandle)
default:
return fmt.Errorf("Unknown sniffer type: %s", sniffer.config.Type)
}
return nil
}