GoPacket - parse Dot11 packets

Getting Help
1

Hi everyone,

I’m trying to gopacket to parse the packets of a .pcap file and pretty much to get all the information in it, until I get either truncated information or an error IF I try to use a filter.

package main

import (
    "fmt"
    "github.com/google/gopacket"
    "github.com/google/gopacket/pcap"
    //"github.com/google/gopacket/layers"
    "log"
)

var (
    pcapFile string = "myFile.pcap"
    handle   *pcap.Handle
    err      error
)

func main() {
    // Open file instead of device
    handle, err = pcap.OpenOffline(pcapFile)
    if err != nil { log.Fatal(err) }
    defer handle.Close()

    // Loop through packets in file
    packetSource := gopacket.NewPacketSource(handle, handle.LinkType())
    for packet := range packetSource.Packets() {
        fmt.Println
      }
}

This returns:

PACKET: 122 bytes, wire length 122 cap length 122 @ 2017-06-11 02:57:03.133873 +0100 WEST
- Layer 1 (36 bytes) = RadioTap	{Contents=[..36..] Payload=[..86..] Version=0 Length=36 Present=2684370991 TSFT=661956589449 Flags=FCS Rate=1 Mb/s ChannelFrequency=2412 MHz ChannelFlags=CCK,Ghz2 FHSS=0 DBMAntennaSignal=-91 DBMAntennaNoise=0 LockQuality=0 TxAttenuation=0 DBTxAttenuation=0 DBMTxPower=0 Antenna=0 DBAntennaSignal=0 DBAntennaNoise=0 RxFlags= TxFlags= RtsRetries=0 DataRetries=0 MCS= AMPDUStatus=ref#0 VHT=}
- Layer 2 (24 bytes) = Dot11	{Contents=[..24..] Payload=[..58..] Type=DataQOSData Proto=0 Flags=TO-DS,WEP DurationID=0 Address1=11:22:33:44:55:66 Address2=00:11:22:33:44:55 Address3=11:22:33:44:55:66 Address4= SequenceNumber=0 FragmentNumber=0 Checksum=4262477891}
- Layer 3 (58 bytes) = Dot11WEP	{Contents=[..58..] Payload=[]}

PACKET: 116 bytes, wire length 116 cap length 116 @ 2017-06-11 02:57:03.243457 +0100 WEST
- Layer 1 (18 bytes) = RadioTap	{Contents=[..18..] Payload=[..102..] Version=0 Length=18 Present=18478 TSFT=0 Flags= Rate=1 Mb/s ChannelFrequency=2417 MHz ChannelFlags=CCK,Ghz2 FHSS=0 DBMAntennaSignal=-25 DBMAntennaNoise=0 LockQuality=0 TxAttenuation=0 DBTxAttenuation=0 DBMTxPower=0 Antenna=1 DBAntennaSignal=0 DBAntennaNoise=0 RxFlags= TxFlags= RtsRetries=0 DataRetries=0 MCS= AMPDUStatus=ref#0 VHT=}
- Layer 2 (24 bytes) = Dot11	{Contents=[..24..] Payload=[..74..] Type=DataQOSData Proto=0 Flags=TO-DS,WEP DurationID=314 Address1=00:11:22:33:44:55 Address2=11:22:33:44:55:66 Address3=00:11:22:33:44:55 Address4= SequenceNumber=0 FragmentNumber=0 Checksum=412506031}
- Layer 3 (74 bytes) = Dot11WEP	{Contents=[..74..] Payload=[]}

I would like to see for example the SSID of the packets or more info inside each layer but everytime I try to drill down the items I get:

RadioTap
Dot11
Dot11WEP
RadioTap
Dot11
Dot11WEP

CODE FOR THE ABOVE OUTPUT

package main

// Use tcpdump to create a test file
// tcpdump -w test.pcap
// or use the example above for writing pcap files

import (
    "fmt"
    "github.com/google/gopacket"
    "github.com/google/gopacket/pcap"
    //"github.com/google/gopacket/layers"
    "log"
)

var (
    pcapFile string = "myFile.pcap"
    handle   *pcap.Handle
    err      error
)

func main() {
    // Open file instead of device
    handle, err = pcap.OpenOffline(pcapFile)
    if err != nil { log.Fatal(err) }
    defer handle.Close()

    // Loop through packets in file
    packetSource := gopacket.NewPacketSource(handle, handle.LinkType())
    for packet := range packetSource.Packets() {
      for _, p := range packet.Layers() {
        for _, b := range p.LayerType() {
          fmt.Println(b)
        }
      }
  	}
}

But in reality I would like to Know the SSID/BSSID and the flags inside the packtet from Dot11.

2

You will probably need to type assert the layer to the correct type and then inspect its properties.

3

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