ptexplorer

Convert Packet Tracer files (.pkt/.pka) to XML and vice versa.

Packet Tracer is a visual simulation tool designed by Cisco Systems that allows users to create network topologies and imitate modern computer networks. The software allows users to simulate the configuration of Cisco routers and switches using a simulated command line interface.

I was kind of curious about the file format used by Packet Tracer. So, after some reverse engineering and analysis here is the result. This tool allow you to convert the binary format of the .pkt/.pka to a readable XML file. You can also revert an XML back to a Packet Tracer file.

Description

The Packet Tracer files (.pkt/.pka) contain the network topology details, configurations and some other information. When you open one of these files, it looks like random binary data :

$ hexdump -C sample.pkt
00000000  23 22 a4 31 67 82 f0 41  70 69 82 d0 c5 e8 fb 4b  |#".1g..Api.....K|
00000010  d2 f9 de a1 0b b4 57 22  a9 20 85 98 4b 1f 04 0f  |......W". ..K...|
00000020  cb 8c b6 4e ea bb d9 e0  08 bc ef d2 76 64 00 0d  |...N........vd..|
00000030  06 55 8a 68 6e ef cc b7  25 8f 0a 25 cd 6f 48 7d  |.U.hn...%..%.oH}|
00000040  7d 0c 78 0e b8 30 00 7c  13 6c 7b 86 bc 48 32 fc  |}.x..0.|.l{..H2.|
00000050  79 34 a5 57 e8 4c b1 6f  f2 64 a7 51 04 a8 66 11  |y4.W.L.o.d.Q..f.|
00000060  d3 d9 63 18 84 29 26 30  bd 7f 1f 5e 6a ec 7b 81  |..c..)&0...^j.{.|
00000070  97 b7 c8 14 72 46 07 4a  c9 30 cc e0 fd 36 90 d7  |....rF.J.0...6..|
00000080  01 39 95 83 57 40 00 31  92 15 68 ba cb 28 aa 01  |.9..W@.1..h..(..|
00000090  5d a9 43 39 bf fa 6f e1  91 e4 6d ae 91 b7 b3 d7  |].C9..o...m.....|
000000a0  1a e8 c3 3a 76 28 b4 4e  33 b9 8e df 9e 10 6e 76  |...:v(.N3.....nv|

[...]

I did some reverse engineering on it and discovered that is was in fact a compressed XML file (with zlib). However, the compressed file had some kind of encryption. Each byte of the file was xored with the file size as key :

encrypted_byte_0 XOR (file_size - 0) = cleartext_byte_0
encrypted_byte_1 XOR (file_size - 1) = cleartext_byte_1
encrypted_byte_2 XOR (file_size - 2) = cleartext_byte_2
encrypted_byte_3 XOR (file_size - 3) = cleartext_byte_3

[...]

So basically, this script simply reverse the XOR and uncompress the file. The result is an XML file :

<PACKETTRACER5>
 <VERSION>5.2.0.0068</VERSION>
 <NETWORK>
  <DEVICES>
   <DEVICE>
    <ENGINE>
     <TYPE model="1841" >Router</TYPE>
     <NAME translate="true" >Internal</NAME>
     <POWER>true</POWER>
     <DESCRIPTION></DESCRIPTION>
     <MODULE>
      <TYPE>eNonRemovableModule</TYPE>

[...]

Note : Once XORed, the 4 first bytes contain the file size uncompressed. The script takes care of removing them before uncompressing the file.

Install

Checkout the source: https://github.com/axcheron/ptexplorer.git

No dependencies required.

Getting Started

$ python3 ptexplorer.py -h
usage: ptexplorer.py [-h] [-d | -e] infile outfile

Convert Packet Tracer files (.pkt/.pka) to XML and vice versa

positional arguments:
  infile        Packet Tracer file
  outfile       Output file (XML)

optional arguments:
  -h, --help    show this help message and exit
  -d, --decode  Converts Packet Tracer file to XML
  -e, --encode  Converts XML to Packet Tracer File

# Decoding
$ python3 ptexplorer.py -d sample.pka sample.xml
[*] Opening Packet Tracer file 'sample.pka'
[*] File size compressed = 164664 bytes
[*] File size uncompressed = 3475692 bytes
[*] Writing XML to 'sample.xml'

# Encoding
$ python3 ptexplorer.py -e sample.xml sample.pkt
[*] Opening XML file 'sample.xml'
[*] File size uncompressed = 3475692 bytes
[*] File size compressed = 164664 bytes
[*] Writing PKT to 'sample.pkt'

License

This project is released under the MIT License. See LICENCE file.