.. 标题：NAT/PAT 表可视化工具
.. slug：nat-pat-Visualizer
.. 日期: 2026-03-27 12:00:00 世界标准时间
..标签：网络、nat、pat、防火墙、计算器、工具
..类别：计算器
..链接：
.. 描述：模拟 PAT 过载映射并可视化 NAT 表容量、端口耗尽阈值和网络地址转换规划的故障情况。
..类型：文本
<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">
PAT 容量计算器
<div class="calc-header">
<h2>NAT/PAT 表可视化工具</h2>
<p>模拟 PAT 过载映射、计算 NAT 表容量并可视化端口耗尽阈值。</p>
<div class="input-grid">
<div class="input-group">
<label>内部主机数量</label>
<input id="insideHosts" max="100000" min="1" type="number" value="200"/>
</div>
<div class="input-group">
<label>外部 IP（PAT 池大小）</label>
<input id="outsideIps" max="255" min="1" type="number" value="1"/>
</div>
<div class="input-group">
<label>每台主机的平均同时会话数</label>
<input id="sessPerHost" max="1000" min="1" type="number" value="20"/>
</div>
<div class="input-group">
<label>协议</label>
<select id="natProto">
<option selected="" value="tcp">传输控制协议</option>
<option value="udp">UDP协议</option>
<option value="both">TCP + UDP（组合）</option>
</select>
</div>
</div>
<div class="button-container">
<button class="calc-button" onclick="calcPat()">计算</button>
</div>
</div>
<div class="result-section" id="patResult" style="display:none">
<div class="section-header">PAT 容量结果</div>
<div class="section-content" id="patResultContent"></div>
</div>
PAT入门模拟器
<div class="calc-header" style="margin-top: 30px;">
<h2>PAT入门模拟器</h2>
<p>模拟添加 NAT 条目以查看转换表的增长。</p>
<div class="input-grid">
<div class="input-group">
<label>内部本地IP</label>
<input id="simInsideIp" type="text" value="192.168.1.10"/>
</div>
<div class="input-group">
<label>本地港口内</label>
<input id="simInsidePort" max="65535" min="1" type="number" value="54321"/>
</div>
<div class="input-group">
<label>外部全球IP</label>
<input id="simOutsideIp" type="text" value="203.0.113.1"/>
</div>
<div class="input-group">
<label>目的IP:端口</label>
<input id="simDstIpPort" type="text" value="1.2.3.4:80"/>
</div>
</div>
<div class="button-container">
<button class="calc-button" onclick="addNatEntry()">添加条目</button>
<button class="calc-button" onclick="clearNatTable()" style="background:#888">清除表格</button>
</div>
</div>
<div class="result-section" id="natTableSection" style="display:none">
<div class="section-header">NAT 转换表</div>
<div class="section-content">
<div id="natTable"></div>
</div>
</div>
端口耗尽参考
<div class="result-section" style="margin-top: 30px;">
<div class="section-header">端口耗尽参考</div>
<div class="section-content">
<table>
<tr><th>平台</th><th>PAT 端口范围</th><th>每个 IP 的端口数</th><th>最大翻译量</th></tr>
<tr><td>思科 IOS/IOS-XE</td><td>1024–65535</td><td>64,512</td><td>64,512 × 外部 IP</td></tr>
<tr><td>思科ASA</td><td>1024–65535（默认）</td><td>64,512</td><td>受 xlate 表内存限制</td></tr>
<tr><td>Linux iptables/nftables</td><td>1024–65535（默认）</td><td>64,512</td><td>受 conntrack 表大小限制</td></tr>
<tr><td>Windows 服务器 NAT</td><td>1025–5000（旧版）/1024–65535</td><td>63,511</td><td>注册表可调</td></tr>
<tr><td>RFC 4787（行为）</td><td>建议保留源端口</td><td>—</td><td>每端点映射</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>