How to change a packet data with scapy?

Question

How can one change a packet data with scapy?

I tried to use sniff() and then send() the edited packet, but it won't work as the original packet has already reached it's destination.

Answer 1

"but it won't work as the original packet has already reached it's destination."

So first you need to setup some MiTM solution so all the communications between both ends traverse though your device, and let you modifiy packet data.

Some wll known software pacakages for this functionality /attack are ettercap and cain/abel.