.. tiêu đề: Trình hiển thị bảng NAT/PAT
.. sên: nat-pat-visualizer
.. ngày: 27-03-2026 12:00:00 UTC
.. tags: mạng, nat, pat, tường lửa, máy tính, công cụ
.. thể loại: Máy tính
.. liên kết:
.. mô tả: Mô phỏng ánh xạ quá tải PAT và trực quan hóa dung lượng bảng NAT, ngưỡng cạn kiệt cổng và các điều kiện lỗi khi lập kế hoạch dịch địa chỉ mạng.
.. loại: văn bản
<style>
.calc-container { max-width: 900px; margin: 20px auto; padding: 20px; }
.calc-header { margin-bottom: 30px; padding: 25px; background: linear-gradient(135deg, #667eea 0%, #764ba2 100%); border-radius: 12px; box-shadow: 0 4px 6px rgba(0,0,0,0.1); color: white; }
.calc-header h2 { margin-top: 0; color: white; font-size: 28px; margin-bottom: 10px; }
.calc-header p  { margin: 10px 0; opacity: 0.95; font-size: 15px; }
.input-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(220px, 1fr)); gap: 15px; margin-top: 20px; }
.input-group { display: flex; flex-direction: column; }
.input-group label { margin-bottom: 8px; font-weight: 600; color: rgba(255,255,255,0.95); font-size: 14px; }
.input-group input, .input-group select { padding: 14px; font-size: 14px; border: 2px solid rgba(255,255,255,0.3); border-radius: 6px; background: rgba(255,255,255,0.95); transition: all 0.3s ease; box-sizing: border-box; }
.input-group input:focus, .input-group select:focus { outline: none; border-color: #4CAF50; background: white; box-shadow: 0 0 0 3px rgba(76,175,80,0.1); }
.button-container { margin-top: 20px; display: flex; justify-content: center; gap: 10px; flex-wrap: wrap; }
.calc-button { padding: 14px 35px; font-size: 16px; background: #4CAF50; color: white; border: none; border-radius: 6px; cursor: pointer; font-weight: bold; transition: all 0.3s ease; box-shadow: 0 2px 4px rgba(0,0,0,0.2); }
.calc-button:hover { background: #45a049; transform: translateY(-1px); box-shadow: 0 4px 8px rgba(0,0,0,0.3); }
.calc-button:active { background: #3d8b40; transform: translateY(0); }
.help-text { margin-top: 15px; font-size: 14px; color: rgba(255,255,255,0.9); background: rgba(0,0,0,0.1); padding: 10px 15px; border-radius: 4px; }
.result-section { background: white; border: 1px solid #e0e0e0; border-radius: 8px; margin-top: 20px; overflow: hidden; box-shadow: 0 2px 4px rgba(0,0,0,0.05); transition: all 0.3s ease; }
.result-section:hover { box-shadow: 0 4px 8px rgba(0,0,0,0.1); }
.section-header { background: linear-gradient(135deg, #4CAF50 0%, #45a049 100%); color: white; padding: 15px 20px; font-size: 18px; font-weight: bold; }
.section-content { padding: 20px; background: #fafafa; }
.result-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(200px, 1fr)); gap: 15px; }
.data-row { display: flex; flex-direction: column; padding: 15px; background: white; border-radius: 6px; border-left: 4px solid #4CAF50; box-shadow: 0 1px 3px rgba(0,0,0,0.05); }
.data-label { font-weight: bold; color: #555; font-size: 13px; margin-bottom: 8px; text-transform: uppercase; letter-spacing: 0.5px; }
.data-value { color: #4CAF50; font-family: 'Courier New', monospace; font-size: 20px; font-weight: bold; }
.info-box { margin-top: 15px; padding: 15px; background: #e3f2fd; color: #1565c0; border-radius: 8px; border-left: 4px solid #2196F3; font-size: 14px; line-height: 1.6; }
table { width: 100%; border-collapse: collapse; }
th { background: linear-gradient(135deg, #4CAF50 0%, #45a049 100%); color: white; padding: 10px; text-align: left; }
td { padding: 8px 10px; border-bottom: 1px solid #eee; font-size: 13px; }
tr:hover td { background: #f8fff8; }
@media (max-width: 768px) { .input-grid, .result-grid { grid-template-columns: 1fr; } .calc-header h2 { font-size: 22px; } .calc-container { padding: 10px; } }
/* Page-specific */
.port-bar { background: #e0e0e0; border-radius: 4px; height: 12px; overflow: hidden; margin-top: 6px; }
.port-bar-fill { background: #4CAF50; height: 100%; transition: width 0.4s ease; }
.metric-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(200px, 1fr)); gap: 15px; }
.metric-card { display: flex; flex-direction: column; padding: 15px; background: white; border-radius: 6px; border-left: 4px solid #4CAF50; box-shadow: 0 1px 3px rgba(0,0,0,0.05); }
.metric-label { font-weight: bold; color: #555; font-size: 13px; margin-bottom: 6px; text-transform: uppercase; }
.metric-value { color: #4CAF50; font-family: 'Courier New', monospace; font-size: 18px; font-weight: bold; }
.result-highlight { color: #4CAF50; font-weight: bold; font-size: 1.2em; }
</style>
<div class="calc-container">
Máy tính công suất PAT
<div class="calc-header">
<h2>Trình hiển thị bảng NAT/PAT</h2>
<p>Mô phỏng ánh xạ quá tải PAT, tính toán dung lượng bảng NAT và trực quan hóa các ngưỡng cạn kiệt cổng.</p>
<div class="input-grid">
<div class="input-group">
<label>Số lượng máy chủ bên trong</label>
<input id="insideHosts" max="100000" min="1" type="number" value="200"/>
</div>
<div class="input-group">
<label>IP bên ngoài (kích thước nhóm PAT)</label>
<input id="outsideIps" max="255" min="1" type="number" value="1"/>
</div>
<div class="input-group">
<label>Số phiên đồng thời trung bình trên mỗi máy chủ</label>
<input id="sessPerHost" max="1000" min="1" type="number" value="20"/>
</div>
<div class="input-group">
<label>Giao thức</label>
<select id="natProto">
<option selected="" value="tcp">TCP</option>
<option value="udp">UDP</option>
<option value="both">TCP + UDP (kết hợp)</option>
</select>
</div>
</div>
<div class="button-container">
<button class="calc-button" onclick="calcPat()">Tính toán</button>
</div>
</div>
<div class="result-section" id="patResult" style="display:none">
<div class="section-header">Kết quả năng lực PAT</div>
<div class="section-content" id="patResultContent"></div>
</div>
Trình mô phỏng mục nhập PAT
<div class="calc-header" style="margin-top: 30px;">
<h2>Trình mô phỏng mục nhập PAT</h2>
<p>Mô phỏng thêm các mục NAT để xem bảng dịch phát triển.</p>
<div class="input-grid">
<div class="input-group">
<label>Bên trong IP cục bộ</label>
<input id="simInsideIp" type="text" value="192.168.1.10"/>
</div>
<div class="input-group">
<label>Bên trong cảng địa phương</label>
<input id="simInsidePort" max="65535" min="1" type="number" value="54321"/>
</div>
<div class="input-group">
<label>Bên ngoài IP toàn cầu</label>
<input id="simOutsideIp" type="text" value="203.0.113.1"/>
</div>
<div class="input-group">
<label>IP đích:Cổng</label>
<input id="simDstIpPort" type="text" value="1.2.3.4:80"/>
</div>
</div>
<div class="button-container">
<button class="calc-button" onclick="addNatEntry()">Thêm mục nhập</button>
<button class="calc-button" onclick="clearNatTable()" style="background:#888">Xóa bảng</button>
</div>
</div>
<div class="result-section" id="natTableSection" style="display:none">
<div class="section-header">Bảng dịch NAT</div>
<div class="section-content">
<div id="natTable"></div>
</div>
</div>
Tham chiếu cạn kiệt cổng
<div class="result-section" style="margin-top: 30px;">
<div class="section-header">Tham chiếu cạn kiệt cổng</div>
<div class="section-content">
<table>
<tr><th>Nền tảng</th><th>Phạm vi cổng PAT</th><th>Cổng trên mỗi IP</th><th>Bản dịch tối đa</th></tr>
<tr><td>Cisco IOS/IOS-XE</td><td>1024–65535</td><td>64.512</td><td>64.512 × IP bên ngoài</td></tr>
<tr><td>Cisco ASA</td><td>1024–65535 (mặc định)</td><td>64.512</td><td>Bị giới hạn bởi bộ nhớ bảng xlate</td></tr>
<tr><td>Linux iptables/nftables</td><td>1024–65535 (mặc định)</td><td>64.512</td><td>Bị giới hạn bởi kích thước bảng conntrack</td></tr>
<tr><td>Máy chủ Windows NAT</td><td>1025–5000 (cũ) / 1024–65535</td><td>63.511</td><td>Có thể điều chỉnh sổ đăng ký</td></tr>
<tr><td>RFC 4787 (HƯỚNG DẪN)</td><td>Đề nghị bảo quản cổng nguồn</td><td>—</td><td>Ánh xạ mỗi điểm cuối</td></tr>
</table>
</div>
</div>
</div>
<script>
const PAT_PORTS = 64512; // 65535 - 1024 + 1 (ports 1024-65535)
let natEntries = [];
let nextPatPort = 1024;

function calcPat() {
    const hosts = parseInt(document.getElementById('insideHosts').value);
    const ips = parseInt(document.getElementById('outsideIps').value);
    const sessPerHost = parseInt(document.getElementById('sessPerHost').value);
    const proto = document.getElementById('natProto').value;
    const section = document.getElementById('patResult');
    const content = document.getElementById('patResultContent');
    section.style.display = 'block';

    if (isNaN(hosts) || isNaN(ips) || isNaN(sessPerHost) || hosts < 1 || ips < 1 || sessPerHost < 1) {
        content.innerHTML = '<div class="info-box" style="background:#fff5f5;color:#dc3545;border-color:#dc3545"><strong>Invalid input. All fields must be positive numbers.</strong></div>';
        return;
    }

    const poolSize = proto === 'both' ? PAT_PORTS * 2 * ips : PAT_PORTS * ips;
    const totalSessions = hosts * sessPerHost;
    const utilPct = Math.min((totalSessions / poolSize) * 100, 100);
    const isExhausted = totalSessions > poolSize;
    const overflow = isExhausted ? totalSessions - poolSize : 0;

    const barColor = utilPct > 90 ? '#dc3545' : utilPct > 70 ? '#f7971e' : '#4CAF50';

    content.innerHTML = `
        <div class="metric-grid">
            <div class="metric-card"><div class="metric-value">${poolSize.toLocaleString()}</div><div class="metric-label">Total PAT slots (pool)</div></div>
            <div class="metric-card"><div class="metric-value">${totalSessions.toLocaleString()}</div><div class="metric-label">Sessions required</div></div>
            <div class="metric-card"><div class="metric-value">${utilPct.toFixed(1)}%</div><div class="metric-label">Pool utilization</div></div>
            ${isExhausted ? `<div class="metric-card" style="border-left-color:#dc3545"><div class="metric-value" style="color:#dc3545">${overflow.toLocaleString()}</div><div class="metric-label" style="color:#dc3545">Sessions DROPPED (overflow)</div></div>` : ''}
        </div>
        <div class="port-bar" style="height:24px;margin:15px 0;">
            <div class="port-bar-fill" style="width:${Math.min(utilPct, 100)}%;background:${barColor};display:flex;align-items:center;justify-content:center;color:white;font-size:12px;font-weight:bold;">
                ${utilPct.toFixed(1)}%
            </div>
        </div>
        <div class="info-box" style="${isExhausted ? 'background:#fff5f5;color:#dc3545;border-color:#dc3545' : 'background:#f5fff7;color:#155724;border-color:#28a745'}">
            ${isExhausted
                ? `<strong>Port exhaustion!</strong> Need ${Math.ceil(totalSessions / PAT_PORTS)} outside IPs to support current session load.`
                : `<strong>Sufficient capacity.</strong> ${(poolSize - totalSessions).toLocaleString()} PAT slots remaining.`}
            <br><em>Formula: ${ips} IP(s) × ${proto === 'both' ? '2 × ' : ''}64,512 ports = ${poolSize.toLocaleString()} slots</em>
        </div>`;
}

function addNatEntry() {
    const insideIp = document.getElementById('simInsideIp').value.trim();
    const insidePort = parseInt(document.getElementById('simInsidePort').value);
    const outsideIp = document.getElementById('simOutsideIp').value.trim();
    const dstIpPort = document.getElementById('simDstIpPort').value.trim();

    if (!insideIp || !outsideIp || !dstIpPort || isNaN(insidePort)) {
        alert('Fill in all simulator fields.');
        return;
    }

    const patPort = nextPatPort++;
    if (patPort > 65535) { alert('PAT pool exhausted (port 65535 reached).'); return; }

    natEntries.push({ insideIp, insidePort, outsideIp, patPort, dstIpPort, proto: 'TCP' });
    renderNatTable();

    // Auto-increment inside port for easy demo
    document.getElementById('simInsidePort').value = insidePort + 1;
}

function clearNatTable() {
    natEntries = [];
    nextPatPort = 1024;
    renderNatTable();
}

function renderNatTable() {
    const div = document.getElementById('natTable');
    const section = document.getElementById('natTableSection');
    if (!natEntries.length) {
        section.style.display = 'none';
        div.innerHTML = '';
        return;
    }
    section.style.display = 'block';
    let rows = natEntries.map((e, i) => `<tr>
        <td>${i + 1}</td>
        <td>${e.insideIp}:${e.insidePort}</td>
        <td>${e.outsideIp}:${e.patPort}</td>
        <td>${e.dstIpPort}</td>
        <td>${e.proto}</td>
    </tr>`).join('');
    div.innerHTML = `<table>
        <tr><th>#</th><th>Inside Local</th><th>Inside Global (PAT)</th><th>Destination</th><th>Proto</th></tr>
        ${rows}
    </table>
    <div style="margin-top:8px;color:#666;font-size:13px">${natEntries.length} entries | Next PAT port: ${nextPatPort}</div>`;
}
</script>