On your QRadar Community Edition or Linux CentOS distro you can get tcpreplay from the EPEL repo.
Just do :
root@qradarCE ~] yum --enablerepo=extras install epel-release [root@qradarCE ~]# yum install tcpreplay
This will install tcpdump and tcpreplay on your Linux Centos Qradar CE.
For information EPEL (Extra Packages for Enterprise Linux) is open source and free community based repository project from Fedora team. This is for RHEL, CentOS, and Scientific Linux.
Epel project is not a part of RHEL/Cent OS but it is designed for these Linux distributions by providing lots of open source packages like networking, sys admin, programming, monitoring and so on.
Most of the epel packages are maintained by Fedora repo.