Tcpdump is getting to traffic on a network, refer tcpdump from the link :

The current developments version of tcpdump and libpcap is free from the GitHub, You can clone the tcpdump GitHub repository using

    git clone
    git clone
You can then configure and compile the source via the normal GNU autoconf method.

The simple shell script do take a backup current tcpdump logs  every 10 minutes into a tcpdump.log in your home directory

/usr/sbin/tcpdump -i eth0 ip >> ~/tcpdump.log &
sleep 5m
pkill -9 tcpdump

If you would like to set the cron job every 10 minutes,

Open a crontab file

# vim /etc/cron/crontab
0,10,20,30,40,50 * * * *  /bin/sh /root/

You might restart the cron service.