What happens when a TCP stream suddenly receives a packet that was not destined for the current stream?

Issue

• In the middle of a TCP session, possibly during the three-way-handshake, a random packet from another TCP session is sent to the wrong system. What is the response from the kernel that can be expected when this happens?

• For example, in this TCP session:

No.     Time                       Source                Destination           Protocol Length Info
    285 2013-06-19 16:15:46.697294 192.168.1.4          172.34.124.220        TCP      66     50221 > http [SYN] Seq=3960902987 Win=14600 Len=0 MSS=1460 WS=7
    286 2013-06-19 16:15:46.697703 172.34.124.220        192.168.1.4          TCP      60     [TCP ACKed lost segment] http > 50221 [PSH, ACK] Seq=3530742827 Ack=3961023912 Win=16560 Len=0

• In the above scenario, a client sends a SYN to port 80 with ephemeral port 50221 (packet 285). The client is expecting a SYN-ACK in response as per TCP/IP standards for opening a new socket - in this instance, however, it receives an ACK that was not intended for this current stream (packet 286).