However, please note that injecting data into the TCP stream is not as easy as it may seem at the first look, because you should properly shift SEQ and ACK fields in your newly inserted packet and all sequent packets.
Before I try to inject a packet into the TCP stream I thought I would check with you to see if there is another way to do what I need at the winsock level. If application 1 and application 2 are communicating via TCP using windows sockets on a set port, is there a way from my intercepting application to send a message to application 1 using Winsock so that is appears it came from application 2? I can’t figure out how to send messages using winsock using a port that is already open.
(e.g. App1 is connected to App2 on local port 9999, I want App3 to be able to send messages to App1 using local local port 9999 as well).