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TCP Flow Graph not displaying packets length on localhost

asked 2021-10-11 10:08:21 +0000


I am using wireshark as a teacher for students to investigate how the sequence and acknowledgment numbers of a TCP flow works. To simplify the data capture, I am asking them to run some server/client on IPv6 localhost. When displaying the corresponding Flow Graph, the two vertical lines that would correspond to the client and the server seems to collapse together as a single line (with header ::1) resulting in the flags and packet length missing on the graph, which is a vital piece of information for this purpose ^^

Is there anyway to get the graph split the two lines as it does when the client and server addresses are different?

Many thanks!

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answered 2021-10-11 16:15:37 +0000

Chuckc gravatar image

Can you provide a sample capture file and open a Gitlab issue? Please include a link back to this question.

Testing with tshark -z flow,any,standard reveals that it also doesn't display properly for traffic to/from localhost.

p$ tshark -r ./*localhost_http* -q -z flow,any,standard,tcp.port==1026
|Time     |                             |
|         |
|7.595188  ** (tshark:8684) 11:14:03.813463 [GLib CRITICAL] -- g_string_erase: assertion 'pos_unsigned + len_unsigned
 <= string->len' failed
|         1026 → 80 [SYN] Seq=          |TCP: 1026 → 80 [SYN] Seq=0 Win=65535 Len=0 MSS=65495 WS=256 SACK_PERM=1
|          ** (tshark:8684) 11:14:03.825533 [GLib CRITICAL] -- g_string_erase: assertion 'pos_unsigned + len_unsigned
 <= string->len' failed
|(1026)   ------------------>  (80)    |
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Asked: 2021-10-11 10:03:04 +0000

Seen: 183 times

Last updated: Oct 11 '21