> The man file isn't particularly useful for figuring out how what the 
> output means, so here is a few lines:
> 
> 15:04:57.045705 IP toil.robots.cse.wustl.edu.53552 > 
> 192.168.1.115.49680: . 931064:932512(1448) ack 1 win 108 
> <nop,nop,timestamp 4970372 497156321>
> 15:04:57.045710 IP 192.168.1.115.49680 > 
> toil.robots.cse.wustl.edu.53552: . ack 931064 win 33304 
> <nop,nop,timestamp 497156335 4970352>
> 15:04:57.045711 IP 192.168.1.1.http > 192.168.1.115.49706: P 1:351(350) 
> ack 597 win 6556 <nop,nop,timestamp 172066583 497156334>
> 15:04:57.045777 IP 192.168.1.115.49680 > 
> toil.robots.cse.wustl.edu.53552: . ack 933960 win 33304 
> <nop,nop,timestamp 497156335 4970372>
> 15:04:57.045809 IP 192.168.1.115.49706 > 192.168.1.1.http: . ack 351 win 
> 33129 <nop,nop,timestamp 497156335 172066583>
> > Have you tried using compressed image transports?

Strange, I have never seen tcpdump not print packet lengths. Try adding
-e.