Hello!
Did you find the answer?
I had the same problem - i've got some packets from pcap file, stored it
data into DB.
When i'm trying to create new packet from this stored data its works well,
but packet metadata is empty.
On Monday, 24 April 2017 23:45:55 UTC+3, Chun Zhang wrote:
>
> Hi, all,
>
> I am trying to capture a GRE tunneled packet and get rid off the GRE
> header to retrieve the encapsulated packet.
>
> The code is quite simple, I basically grabs the GRE tunneled packet and
> build a new one from its payload. The problem I have here is the MetaData
> of the packet1 channel is completely empty, even though the decoded layers
> look just fine.
>
> Can anybody help me to figure out where I made the mistake?
>
> Thanks,
> Chun
>
> --------- code snip ------
> packetSource := gopacket.NewPacketSource(handle, handle.LinkType())
> for packet := range packetSource.Packets() {
> if packet.Layer(layers.LayerTypeGRE) == nil {
> fmt.Println("not gre kets")
> //if this is not a GRE tunneled pkt, then this is
> not what we are looking for
> continue
> }
>
> fmt.Println("find a GRE tunnedl pkt")
> packet1 :=
> gopacket.NewPacket(packet.Layer(layers.LayerTypeGRE).LayerPayload(),
> layers.LinkTypeEthernet, gopacket.Default)
> // shouldn't a channel type of Packet being returned here, with Metadata()
> method implemented?
>
> // Process packet here
> fmt.Println(packet1)
>
> fmt.Println("capture lenght:",
> packet1.Metadata().CaptureLength, "timestamp:",
> packet1.Metadata().Timestamp, "capture info:",
> packet1.Metadata().CaptureInfo)
> w.WritePacket(packet1.Metadata().CaptureInfo,
> packet1.Data())
> packetCount++
>
>
> ------ console print -------- test.pcap is completely empty since the
> capture length from the metadata is 0
>
> find a GRE tunnedl pkt
> PACKET: 64 bytes
> - Layer 1 (14 bytes) = Ethernet {Contents=[..14..] Payload=[..50..]
> SrcMAC=00:04:96:6d:49:00 DstMAC=00:50:56:88:4e:2d EthernetType=Dot1Q
> Length=0}
> - Layer 2 (04 bytes) = Dot1Q {Contents=[0, 69, 8, 0] Payload=[..46..]
> Priority=0 DropEligible=false VLANIdentifier=69 Type=IPv4}
> - Layer 3 (20 bytes) = IPv4 {Contents=[..20..] Payload=[..20..]
> Version=4 IHL=5 TOS=16 Length=40 Id=25729 Flags=DF FragOffset=0 TTL=59
> Protocol=TCP Checksum=6231 SrcIP=10.6.105.21 DstIP=10.68.69.137 Options=[]
> Padding=[]}
> - Layer 4 (20 bytes) = TCP {Contents=[..20..] Payload=[]
> SrcPort=50507 DstPort=22(ssh) Seq=3986061698 Ack=2511277766 DataOffset=5
> FIN=false SYN=false RST=false PSH=false ACK=true URG=false ECE=false
> CWR=false NS=false Window=8039 Checksum=64660 Urgent=0 Options=[]
> Padding=[]}
>
> capture lenght: 0 timestamp: 0001-01-01 00:00:00 +0000 UTC capture info:
> {0001-01-01 00:00:00 +0000 UTC 0 0 0}
>
>
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