.. หัวข้อ: ไดอะแกรมเชิงโต้ตอบของเครื่องสถานะ TCP
.. slug: tcp-state-machine
.. วันที่: 27-03-2026 12:00:00 UTC
.. แท็ก: ระบบเครือข่าย, TCP, rfc793, state-machine, เครื่องคิดเลข, เครื่องมือ
..หมวดหมู่ : เครื่องคิดเลข
.. ลิงค์:
.. คำอธิบาย: แผนภาพเครื่องสถานะ TCP ที่คลิกได้ครอบคลุมสถานะ RFC 793 ทั้งหมด แสดงเหตุการณ์ที่กระตุ้น แพ็กเก็ตที่แลกเปลี่ยน ตัวจับเวลา และคำแนะนำในการวินิจฉัยสำหรับสถานะติดขัดทั่วไป
.. ประเภท: ข้อความ
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<div class="calc-header">
<h2>ไดอะแกรมเชิงโต้ตอบของเครื่องสถานะ TCP</h2>
<p>คลิกโหนดสถานะใดๆ เพื่อดูเหตุการณ์ที่ทริกเกอร์ แพ็กเก็ตที่แลกเปลี่ยน ตัวจับเวลา และเคล็ดลับการวินิจฉัยสถานะที่ติดอยู่</p>
<div class="legend">
<div class="legend-item"><div class="legend-dot" style="background:#28a745"></div>สถานะเริ่มต้น/สิ้นสุด</div>
<div class="legend-item"><div class="legend-dot" style="background:#4CAF50"></div>รัฐปกติ</div>
<div class="legend-item"><div class="legend-dot" style="background:#dc3545"></div>TIME_WAIT / ค้าง</div>
<div class="legend-item"><div class="legend-dot" style="background:#f7971e"></div>รัฐปิด</div>
</div>
</div>
<div class="result-section">
<div class="section-header">แผนภาพสถานะ</div>
<div class="section-content" style="padding:12px">
<div id="cy"></div>
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</div>
<div class="result-section" id="detailPanel">
<div class="section-header">รายละเอียดของรัฐ</div>
<div class="section-content" id="detailContent">
<p style="color:#999">คลิกโหนดสถานะด้านบนเพื่อดูรายละเอียด</p>
</div>
</div>
</div>
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    LISTEN:     { color:'#0f3460', event:'Server calls listen(). Waiting for SYN.',
        packet:'Receives SYN', timer:'—',
        desc:'Server is waiting for an incoming connection request.',
        diagnosis:'Stuck LISTEN: Port not open. Check: ss -lntp | grep &lt;port&gt;' },
    SYN_SENT:   { color:'#0f3460', event:'Client calls connect(). SYN sent.',
        packet:'Sends SYN', timer:'SYN-timeout (~75s)',
        desc:'Client sent SYN, waiting for SYN-ACK.',
        diagnosis:'Stuck SYN_SENT: Firewall dropping SYN, or server not listening. Check MTU/PMTUD if SYN goes out but SYN-ACK never arrives.' },
    SYN_RCVD:   { color:'#0f3460', event:'SYN received. SYN-ACK sent.',
        packet:'Receives SYN, sends SYN-ACK', timer:'SYN-backlog timer',
        desc:'Server received SYN, replied with SYN-ACK, waiting for ACK (3-way handshake).',
        diagnosis:'Many SYN_RCVD: SYN flood / DDoS. Enable tcp_syncookies: sysctl -w net.ipv4.tcp_syncookies=1' },
    ESTABLISHED:{ color:'#28a745', event:'ACK received. Connection open.',
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    CLOSING:    { color:'#f7971e', event:'Both sides send FIN simultaneously.',
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        desc:'Waiting 2×MSL to ensure remote received the final ACK, and to prevent old segments from being accepted by a new connection.',
        diagnosis:'Many TIME_WAIT: Normal under high connection rate. Mitigate: tcp_tw_reuse=1, reduce tcp_fin_timeout, use persistent connections, or load balance across more ports.' },
};

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