Tshark is another application that identical to Tcpdump

No, it's much more powerful - have a look again at the tshark manpage, especially the -T fields and -e options. You can use them to output Wireshark's tcp.options.mss_val field.

As for your output, it looks like the packets don't contain an MSS option, or, if you know the packets do have one, NetPacket::TCP isn't parsing them correctly, in that case file a bug with the module.

You can use them to output Wireshark's tcp.options.mss_val field.

Agreed Tshark will be helpful and more easy to implement wireshark filters. My understanding was Tshark is used with Java. Identical to Tcpdump for Perl. Definitely give a try to use Tshark in Perl. There's a Tshark PM too. I've been parsing input pcap file that don't contain mss option. here is the output with mss option.

Thank you

===output===

$VAR1 = {
          'sack' => 2,
          'mss' => 1460,
          'ws' => 8
        };
[download]

===output===