tcpdump

I wanted to find out if remote X creates a lot of network flows, so I logged into a remote computer with "ssh -Y", started xclock, and then typed tcpdump. Then screen began scrolling up crazily like this:

13:21:00.694367 IP xxx.xxx.xx.xx.45762 > 192.168.1.3.ssh: . ack 60640 win 2003 <nop,nop,timestamp 191668683 75287130>
13:21:00.694430 IP 192.168.1.3.ssh > xxx.xxx.xx.xx.45762: P 70416:70464(48) ack 113 win 501 <nop,nop,timestamp 191668683 75287200>

Was X sending/receiving lots of data even if it seems to be idling? It shouldn't be so silly.. And... Finally I realized what a big mistake I had made... It was like putting a microphone against a loudspeaker...