Wireshark-bugs: [Wireshark-bugs] [Bug 6470] New: tshark badly interprets RFC2554 (SMTP authentic
Date: Wed, 19 Oct 2011 12:38:25 -0700 (PDT)
https://bugs.wireshark.org/bugzilla/show_bug.cgi?id=6470

           Summary: tshark badly interprets RFC2554 (SMTP authentication)
           Product: Wireshark
           Version: 1.4.9
          Platform: x86
        OS/Version: Fedora
            Status: NEW
          Severity: Normal
          Priority: Low
         Component: TShark
        AssignedTo: bugzilla-admin@xxxxxxxxxxxxx
        ReportedBy: franta@xxxxxxxxxxx


Created an attachment (id=7265)
 --> (https://bugs.wireshark.org/bugzilla/attachment.cgi?id=7265)
both here included outputs (without and with display filters)

Build Information:
TShark 1.4.9

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 GLib 2.26.0, with libpcap 1.1.1, without libz, without
POSIX capabilities, without libpcre, with SMI 0.4.8, without c-ares, without
ADNS, with Lua 5.1, without Python, with GnuTLS 2.8.6, with Gcrypt 1.4.5, with
MIT Kerberos, with GeoIP.

Running on Linux 2.6.35.14-96.fc14.i686.PAE, with libpcap version 1.1.1.

Built using gcc 4.5.1 20100924 (Red Hat 4.5.1-4).
--
when decode pcap file previously captured by "tcpdump -w file.pcap port 25"
command, then "tshark -n -r file.pcap" output looks like (I cutted out only
authentication part):

166  44.815436 85.70.171.14 -> 77.75.72.48 SMTP C: AUTH LOGIN
167  44.815560 77.75.72.48 -> 85.70.171.14 SMTP S: 334 VXNlcm5hbWU6
168  44.831403 85.70.171.14 -> 77.75.72.48 SMTP C: am9lc21pdGg=
169  44.831465 77.75.72.48 -> 85.70.171.14 SMTP S: 334 UGFzc3dvcmQ6
170  44.846178 85.70.171.14 -> 77.75.72.48 SMTP C: aWVLMlF1YWg=
171  44.886176 77.75.72.48 -> 85.70.171.14 TCP 25 > 16066 [ACK] Seq=342 Ack=73
Win=5840 Len=0
172  45.474313 77.75.72.48 -> 85.70.171.14 SMTP S: 235 2.0.0 OK Authenticated

which is fine. When process same file using display filter fields, with
command:
'tshark -r file.pcap -n -T fields -e tcp.srcport -e tcp.dstport -e ip.src -e
ip.dst -e smtp.req.command -e smtp.req.parameter -e smtp.response.code -e
smtp.rsp.parameter -R "smtp.req == 1 || smtp.rsp == 1"', then output is as:

16066    25    85.70.171.14    77.75.72.48    AUTH    LOGIN        
25    16066    77.75.72.48    85.70.171.14            334    VXNlcm5hbWU6
16066    25    85.70.171.14    77.75.72.48    am9l    21pdGg=        
25    16066    77.75.72.48    85.70.171.14            334    UGFzc3dvcmQ6
16066    25    85.70.171.14    77.75.72.48    aWVL    lF1YWg=        
25    16066    77.75.72.48    85.70.171.14            235    2.0.0 OK
Authenticated

where is visible that client responses are ruptured at something as
smtp.req.command and smtp.req.parameter with missing character at fifth
position
(e.g. client response "am9lc21pdGg=" is treated as smtp.req.command="am9l" and
smtp.req.parameter="21pdGg=" (and letter "c" isn't in either part).

This should be probably somehow handled better. Or, maybe, constitute another
SMTP display filter field, which wil display full decoded SMTP line as in case
when not using display filter (in this case it would display "C:
am9lc21pdGg=").

Maybe same solution would be sufficient in case of bug no. 6446 (IMAP display
filter) and maybe other protocols - after all, without using display filters &
field names, tshark decodes protocol correctly and for lot of cases (including
my own) it is sufficient, I only want display some additional fields from
TCP/IP/Ethernet layer.

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