TCP Handshake & State Machine Visualizer
TCP Handshake & State Machine Visualizer: Models a documented educational subset of RFC 9293 state transitions for open, close, ACK, FIN, RST, and timeout events. It is not packet capture or a complete TCP implementation.
About this tcp handshake & state machine visualizer
TCP Handshake & State Machine Visualizer — browser-based utility.
How this tool works
Models a documented subset of TCP state and event transitions, including open, close, ACK, FIN, RST, and timeout paths. It is an educational state visualizer rather than packet capture, a complete RFC 9293 implementation, or a network diagnostic.
- Protocol Message De-serialization: Parses raw DNS wire-format byte streams or HAR 1.2 JSON waterfall entries.
- Record Validation & Separation: Enforces RFC 6844 requirements that CAA authorization ('issue', 'issuewild') and reporting ('iodef') tags reside on separate records.
- Waterfall Timing Analysis: Sums network phases (blocked, dns, connect, ssl, send, wait, receive) to evaluate latency waterfalls.
- Visual Diagnostic Reporting: Renders color-coded waterfall timelines and highlights high-latency assets or missing HTTP caching headers.
Worked example
Scenario: Model a local TCP transition from ESTABLISHED on RST.
Sample input:
Processing: Normalize the two text values and consult the bundled transition rule.
Illustrative output:
Limits and verification
Rejects combined single-line CAA records that violate RFC 6844 syntax. In HAR file analysis, protects against multi-gigabyte log allocations by parsing entry streams with memory safety bounds.
Examples demonstrate an expected workflow; they do not prove every input or every branch of an external specification. Check important results with an independent source before using them for money, security, compliance, safety, or irreversible file changes.
Browser processing boundary
Tool input is processed by code running in the browser and is not intentionally sent to a CZOA processing API. The page can still request ordinary site assets, analytics, or advertising when those services are enabled. Browser extensions and managed-device software remain outside this tool's control.
Relevant references
These references govern or help explain the format, protocol, or calculation used here. Listing a reference does not claim certification or complete implementation of every optional feature.
Content owner: CZOA Tools · Last reviewed: 2026-09-15 · Review methodology
How to use it
- Enter, paste, or select your input data into the TCP Handshake & State Machine Visualizer workspace controls.
- Review available parameter fields, units, formats, or options configured for your task.
- Click the action button or observe immediate live calculations rendered in your browser runtime.
- Inspect the resulting output and any diagnostic messages, then copy or download the result if needed.
Frequently asked questions
What does this TCP state tool model?+
It evaluates the bundled state-transition table for text state and event values. For example CLOSED plus SYN returns valid SYN-SENT, LISTEN plus SYN returns SYN-RECEIVED, and ESTABLISHED plus RST returns CLOSED. It is an educational local model, not packet capture, a socket, a network scan, or a complete TCP implementation.
Which inputs and normalizations apply?+
Enter a state and an event, then run locally. Inputs are trimmed and uppercased; spaces in a state become hyphens. Empty state defaults to CLOSED and empty event to SYN. The supported table has named TCP lifecycle states and events such as SYN, SYN-ACK, ACK, FIN and RST; it does not parse packets, sequence numbers, options, timers, ports or payloads.
How are invalid transitions handled?+
If a transition is absent, the result keeps the normalized input state, marks valid false, and explains that the segment is dropped or may generate RST under RFC 9293. RST from any non-CLOSED state is handled specially: SYN-RECEIVED goes to LISTEN; other non-CLOSED states go to CLOSED. This is table behavior, not proof of a remote peer response.
What result does the worked example produce?+
Independent checks matched LISTEN plus SYN to SYN-RECEIVED, ESTABLISHED plus RST to CLOSED, and CLOSED plus FIN as invalid. In the worked example, the tool runs also matched CLOSED plus SYN to SYN-SENT and ESTABLISHED plus RST to CLOSED. Those runs establish this local page path only; they do not inspect or send traffic.