How to save the packets received by a network interface or some port in a file and resend the packets received when needed?

Question

I am doing my work on a server service program on Linux that processes the packets sent to the socket it listens.Their is already a old such service listening on the port doing its job,and I can't stop the old server service, and I need to get the packets sent to the old server and send them to my new server service to make sure it works well .How can I get the packets and resent them to my new service? Is there such a tool or is there some functionality that tools such as tcpdump already provides? Thanks:)

Answer 1

Maybe tcpreplay is what you're looking for.