Lets say I have an application written in python to send a ping or e-mail. How can I change the source IP address of the sent packet to a fake one, using, e.g., Scapy?
Consider that that the IP address assigned to my eth0 is 192.168.0.100. My e-mail application will send messages using this IP. However, I want to manipulate this packet, as soon as it is ready to be sent, so its source IP is not 192.168.0.100 but 192.168.0.101 instead.
I'd like to do this without having to implement a MITM.
You basically want to spoof your ip address.Well I suggest you to read Networking and ip header packets.This can be possible through python but you won't be able to see result as you have spoofed your ip.To be able to do this you will need to predict the sequence numbers.
Send packet and change its source IP