TCP establishes reliable connections using a three-way handshake (SYN, SYN-ACK, ACK). Watch packets flow between client and server, simulate packet loss, and understand retransmission behavior.
The handshake process
Client sends SYN with sequence number. Server responds with SYN-ACK, acknowledging the client and providing its own sequence. Client sends ACK, and the connection is established.
Handling failures
If any packet is lost, TCP uses timeouts and retransmissions. The simulator shows how lost SYN or ACK packets are detected and retransmitted to complete the connection.
Good for
- Learning network protocols
- Understanding connection latency
- Debugging connection issues
- Networking interview preparation
Questions people ask
Why three-way and not two-way?
Three-way handshake ensures both parties can send and receive, and it synchronizes sequence numbers. A two-way handshake cannot confirm the client can receive responses.
What is SYN flood attack?
Attackers send many SYN packets without completing handshakes, exhausting server resources. Defenses include SYN cookies and limiting half-open connections.