pyCologne Python User Group, Cologne, Germany, January, 13th Notes

The Python User Group Cologne (pyCologne) met on January, 13th at the computer centre of the University of Cologne. The meeting was attended by 10 people. German speakers might want to refer to our wiki page http://www.pycologne.de

This time we had a talk about the network-tool Scapy:

"Scapy - Experimenting with network packets" (Dirk Loss)

Dirk introduced the network-tool "Scapy" which allows building as well as analysing network packets. There are some similarities between Scapy and Wireshark, a well known graphical network analyser. Wireshark is also known by its predecessor Etherreal.

Scapy features building and manipulating network packets using an extended python-command-prompt. The '/' (division)-operator is overloaded to represent nesting of a packet-part into another. To nest an ICMP (ping echo-request) packet into an IP-packet you would write: i=IP(dst="8.8.8.8")/ICMP()

Besides the creation of network packets you can use Scapy to:

• Send out network packets
• Sniff network packets and analyse them on the command-line
• Visualize a conversation using the command conversation()
• Visualize the nested structure of an IP-packet with the command pdfdump()
• Create a series of packets with slight, random faults for testing purposes ("Fuzzing")

Analysing complex, high level protocols is difficult. However, Scapy offers state machines to keep track of the conversation.

Dirk did a live presentation of all the mentioned features, which led to a lot of interesting questions during and after the talk.

You can find the slides of Dirk's talk here:

http://dirk-loss.de/scapy/Scapy_pyCologne_2010-01-13_DirkLoss_v1.1.pdf

Other topics

During the rest of the meeting we talked about the following other issues:

• Question for good python introductory material: "Dive into Python" was recommended.
• Martin looks for a solution to generate comments within a C++-library into doc-strings of the corresponding Python-wrapper. There were some answers. However, we could not find a final strategy for doing that. Suggestions are very welcome!
• We would like to encourage participants to do, additionally to the classic talks, short talks or live presentations which need less preparation. The estimated duration of a talk should be announced beforehand for better organization.
• Reimar proposes to organize a "Python-Day" in Cologne and to invite other Python-User-Groups from Germany as well to participate. We will look for 1 or 2 suitable days on a weekend.
  

The minutes of the meeting in German language can be found here.

The next meeting will be held on, Wednesday, February, 10th.

Most of the participants enjoyed the rest of the evening in our usual italian restaurant having food, drinks and friendly conversation.