CODEWITHSUNDEEP
pythonhexwiresharkpcapcisco
Vishnu Indusekharan
Vishnu Indusekharan

Reputation: 41

text2pcap is not detecting the below format

I am trying to convert the hex dump obtained from a Cisco router via embedded packet capture feature to pcap file.

My input format is as listed below

0
   0000:  70E42273 90D2003A 7D36A502 81000183   p."s...:}6......
   0010:  080045C0 003BB1BF 40000106 8FA20A10   ..E..;..@.......
   0020:  91BD0A10 91BEAC03 00B313C4 EE96E803   ................
   0030:  1C875018 3D41832D 0000FFFF FFFFFFFF   ..P.=A.-........
   0040:  FFFFFFFF FFFFFFFF FFFF0013 04         .............
 
 1
   0000:  003A7D36 A50270E4 227390D2 81000183   .:}6..p."s......
   0010:  08004500 00281097 40000106 319E0A10   ..E..([email protected]...
   0020:  91BE0A10 91BD00B3 AC03E803 1C8713C4   ................  
   0030:  EEA95010 7B534936 0000                ..P.{SI6..
 
 2
   0000:  003A7D36 A50270E4 227390D2 81000183   .:}6..p."s......
   0010:  08004500 003B1197 40000106 308B0A10   ..E..;[email protected]...
   0020:  91BE0A10 91BD00B3 AC03E803 1C8713C4   ................
   0030:  EEA95018 7B534508 0000FFFF FFFFFFFF   ..P.{SE.........
   0040:  FFFFFFFF FFFFFFFF FFFF0013 04         .............

The above format is not accepted in text2pcap, as text2pcap is expecting

   0000:  70 E4 22 73 90 D2 00 3A 7D 36 A5 02 81 00 01 83
   0010:  08 00 45 C0 00 3B B1 BF 40 00 01 06 8F A2 0A 10

Is there any converter tools or scripts available for the same?

Upvotes: -2

Views: 1315

Answers (1)

Christopher Maynard
Christopher Maynard

Reputation: 6284

Is there any converter tools or scripts available for the same?

As you know, text2pcap doesn't currently support this data format; however, I have opened a Wireshark bug report so that one day text2pcap may natively support reading data in such a format. Feel free to follow Wireshark Bug 16193 - text2pcap could be enhanced to accept input in other formats for any updates to this enhancement request.

In the meantime, you will either have to write your own script/command(s), find someone to write one for you, or use/modify an existing script/command in order to convert the data into a format readable by text2pcap. To help get you going, I'm providing you with one method that seems to work in my testing. Assuming your output is saved in a dump.in file, you can run the following:

cat dump.in | sed 's/\([0-9A-F]\{2\}\)/\1 /g' | sed 's/\([0-9A-F]\{2\}\) \([0-9A-F]\{2\}\) :  /\1\2  /g' > dump.out

Both cat and sed should be available on most platforms. I actually ran this command on Windows 10 under Cygwin.

NOTE: I am no sed expert, but there are almost certainly sed experts out there who can probably figure out how to get this to work in 1 pass; I couldn't in the time I was willing to spend on this.

Using the command provided, I was able to convert the data to a format that text2pcap could read and then ran text2pcap -a dump.out dump.pcap to generate a valid pcap file. Running tshark -r dump.pcap generates the following output:

1  387 2019-11-12 21:49:23.000000   0.000000 0.000000 10.16.145.189 → 10.16.145.190 BGP 77 KEEPALIVE Message
2  387 2019-11-12 21:49:23.000001   0.000001 0.000001 10.16.145.190 → 10.16.145.189 TCP 58 bgp(179) → 44035 [ACK] Seq=1 Ack=20 Win=31571 Len=0
3  387 2019-11-12 21:49:23.000002   0.000002 0.000001 10.16.145.190 → 10.16.145.189 BGP 77 KEEPALIVE Message

I assume that's the correct and expected output.

See also: How to convert hex dump from 4 hex digit groups to 2 hex digit groups

Upvotes: 1

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