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WiresharkIntegration » History » Revision 8

Revision 7 (Anonymous, 02/19/2016 10:49 PM) → Revision 8/11 (nion, 02/19/2016 10:49 PM)

= Wireshark integration = 

 [http://www.wireshark.org/ wireshark] is a popular Free Software / Open Source protocol analyzer.    Among many 
 other protocols, it includes dissectors for the GSM Layer 2 (TS 04.06 / LAPDm) and 3 (TS 04.8 04.08 / RR,MM,CC). 

 There also is a [wiki:GSMTAP] protocol dissector in recent wireshark versions, which allows 
 real-time capture and decode of GSM protocol messages encapsulated in a GSMTAP (pseudo-header, 
 which is in turn encapsulated in UDP and IP). 

 So if you have a wireshark version with [wiki:GSMTAP] support (>1.4.0), you can have real-time decode and 
 trace of GSM protocol messages. You can also [wiki:wireshark compile wireshark] yourself. 

 The OsmocomBB [wiki:layer23] program sends [wiki:GSMTAP] packets to the localhost (127.0.0.1) address 
 of the loopback interface (lo).    Please note that the wireshark program is doing passive capture, 
 i.e. if nothing is listening on the [wiki:GSMTAP] UDP port (4729), then you will see ICMP port unreachable 
 messages in addition to the GSMTAP messages.    There are two suggested solutions to this: 
  * Change the IP address to a multicast group like 224.0.0.1 (instead of 127.0.0.1) 
  * Run some program that simply opens the UDP port and discards its content, e.g. using {{{nc {{{{nc -u -l -p 4729 > /dev/null}}} 

 == Screenshot == 

 [[Image(gsmtap-wireshark.png, 66%)]]
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