Start tcpdump automatically on boot ?

Hello,

i am running Oleg's 1.9.2.7-10 on an Wl500gx and would like to start tcpdump at boot. I have a mounted and working USB-stick and tcpdump works from the command line.

My idea is to put the following line in /usr/local/sbin/post-boot :

tcpdump host 192.168.1.3 >> /opt/var/log/tcpdump.log

Will this work ? Or will the execution of the script never end and the boot process no be complete ?

(I would like to monitor this specific host on the LAN to see if some malware talks to outer space...)

Cheers
7111