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Wireshark-bugs: [Wireshark-bugs] [Bug 5792] New: T.38 FAX bad decoding

Date: Mon, 28 Mar 2011 23:59:13 -0700 (PDT)
https://bugs.wireshark.org/bugzilla/show_bug.cgi?id=5792

           Summary: T.38 FAX bad decoding
           Product: Wireshark
           Version: 1.4.4
          Platform: Other
        OS/Version: Windows XP
            Status: NEW
          Severity: Normal
          Priority: Low
         Component: Wireshark
        AssignedTo: wireshark-bugs@xxxxxxxxxxxxx
        ReportedBy: Lars.Ruoff@xxxxxxxxxxxxxxxxxx


Created an attachment (id=6095)
 --> (https://bugs.wireshark.org/bugzilla/attachment.cgi?id=6095)
SIP/T.38 Fax trace

Build Information:
Version 1.4.4 (SVN Rev 36110 from /trunk-1.4)

Copyright 1998-2011 Gerald Combs <gerald@xxxxxxxxxxxxx> and contributors.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

Compiled (32-bit) with GTK+ 2.16.6, with GLib 2.22.4, with WinPcap (version
unknown), with libz 1.2.3, without POSIX capabilities, without libpcre, with
SMI
0.4.8, with c-ares 1.7.1, with Lua 5.1, without Python, with GnuTLS 2.8.5, with
Gcrypt 1.4.5, with MIT Kerberos, with GeoIP, with PortAudio V19-devel (built
Mar
 1 2011), with AirPcap.

Running on Windows XP Service Pack 3, build 2600, with WinPcap version 4.1.2
(packet.dll version 4.1.0.2001), based on libpcap version 1.0 branch 1_0_rel0b
(20091008), GnuTLS 2.8.5, Gcrypt 1.4.5, without AirPcap.

--
(Observed in Wireshark Version 1.4.3, confirmed still present in 1.4.4.)
Attached a VoIP network trace for a SIP/T38 FAX call.
Wireshark sees the T38/V21 packets emitted by the receiving FAX-GW (i.e. IP:
192.168.100.89) as malformed although these packets look correct and the FAX
transmission for this call works fine.
Also, in the flow graph of Wireshark, the T38 signals corresponding to these
V21 packets
are all shown wrong :
Frames 46-49 :        signal emitted by the GW = T38/DIS ; signal displayed by
the tool = T38/NSF ??
Frames 54-65 :        signal emitted by the GW = T38/CSI ; signal displayed by
the tool = T38/NSF ??
Frames 215-216 :     signal emitted by the GW = T38/CFR ; signal displayed by
the tool = T38/DCS ??
Frames 1089-1090 : signal emitted by the GW = T38/MCF ; signal displayed by the
tool = T38/DCS ??

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