I'm capturing http traffic with tcpdump and am interested in TCP slow start and how window sizes increase:
$ sudo tcpdump -i eth1 -w wget++.tcpdump tcp and port 80
When I view the dump file with Wireshark the progression of window sizes looks normal, i.e. 5840, 5888, 5888, 8576, 11264, etc...
But when I view the dump file via
$ tcpdump -r wget++.tcpdump -tnN | less
I get what seem to be nonsensical windows sizes ( IP addresses omitted for brevity ):
: S 1069713761:1069713761(0) win 5840 <mss 1460,sackOK,timestamp 24220583 0,nop,wscale 7>
: S 1198053215:1198053215(0) ack 1069713762 win 5672 <mss 1430,sackOK,timestamp 2485833728 24220583,nop,wscale 6>
: . ack 1 win 46 <nop,nop,timestamp 24220604 2485833728>
: . 1:1419(1418) ack 1 win 46 <nop,nop,timestamp 24220604 2485833728>
: P 1419:2002(583) ack 1 win 46 <nop,nop,timestamp 24220604 2485833728>
: . ack 1419 win 133 <nop,nop,timestamp 2485833824 24220604>
: . ack 2002 win 178 <nop,nop,timestamp 2485833830 24220604>
Is there a way to get normal / absolute window sizes on the command line?