.. Titel: Linux TCP Sysctl Tuning Reference
.. slug: linux-tcp-sysctl-reference
.. Datum: 27.03.2026 12:00:00 UTC
.. Tags: Linux, TCP, Sysctl, Leistung, Kernel, Rechner, Tool
.. Kategorie: Taschenrechner
.. Link:
.. Beschreibung: Interaktives Linux-Parameterhandbuch für net.ipv4.tcp_* und net.core.* mit Workload-Voreinstellungen für Massenübertragung, latenzempfindliches RPC, Webserver mit hoher Verbindung und WAN mit langer Fatpipe.
.. Typ: Text
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<div class="calc-container">
<div class="calc-header">
<h2>Linux TCP Sysctl Tuning Reference</h2>
<p>Interaktiv<code style="color:rgba(255,255,255,0.9)">net.ipv4.tcp_*</code>Und<code style="color:rgba(255,255,255,0.9)">net.core.*</code>Parameterhandbuch mit Workload-Voreinstellungen für Massenübertragung, latenzempfindliches RPC, Hochleistungs-Webserver und Long-Fat-Pipe-WAN.</p>
<div class="input-grid">
<div class="input-group">
<label>Suchen / Filtern</label>
<input id="searchInput" oninput="filterParams(this.value)" placeholder="Search parameters..." type="text"/>
</div>
<div class="input-group">
<label>Workload-Voreinstellungen</label>
<div class="preset-row" id="presetRow"></div>
</div>
</div>
</div>
<div class="result-section">
<div class="section-header">TCP-Systemparameter</div>
<div class="section-content" id="paramList">
</div>
<div style="padding: 20px; background: #fafafa; border-top: 1px solid #e0e0e0;">
<button class="copy-all-btn" onclick="copyAll()">Kopieren Sie alle angezeigten Parameter als sysctl-Befehle</button>
</div>
</div>
</div>
<script>
const PARAMS = [
    {
        name: 'net.ipv4.tcp_rmem',
        desc: 'TCP receive buffer sizes: min, default, max (bytes). Kernel auto-tunes between min and max.',
        default: '4096 131072 6291456',
        presets: {
            bulk: '4096 131072 134217728',
            rpc: '4096 87380 4194304',
            web: '4096 131072 16777216',
            wan: '4096 131072 134217728',
        },
        range: 'min 4096; max up to ~1GB (limited by net.core.rmem_max)',
        tags: ['buffer', 'receive', 'window'],
        doc: 'https://www.kernel.org/doc/html/latest/networking/ip-sysctl.html',
    },
    {
        name: 'net.ipv4.tcp_wmem',
        desc: 'TCP send buffer sizes: min, default, max (bytes).',
        default: '4096 16384 4194304',
        presets: {
            bulk: '4096 16384 134217728',
            rpc: '4096 16384 4194304',
            web: '4096 16384 16777216',
            wan: '4096 16384 134217728',
        },
        range: 'min 4096; max up to ~1GB',
        tags: ['buffer', 'send', 'window'],
        doc: 'https://www.kernel.org/doc/html/latest/networking/ip-sysctl.html',
    },
    {
        name: 'net.core.rmem_max',
        desc: 'Maximum receive socket buffer size. Upper bound for tcp_rmem max.',
        default: '212992',
        presets: {
            bulk: '134217728',
            rpc: '4194304',
            web: '16777216',
            wan: '134217728',
        },
        range: '212992 – 2147483647',
        tags: ['buffer', 'receive', 'core'],
        doc: 'https://www.kernel.org/doc/html/latest/networking/ip-sysctl.html',
    },
    {
        name: 'net.core.wmem_max',
        desc: 'Maximum send socket buffer size.',
        default: '212992',
        presets: {
            bulk: '134217728',
            rpc: '4194304',
            web: '16777216',
            wan: '134217728',
        },
        range: '212992 – 2147483647',
        tags: ['buffer', 'send', 'core'],
        doc: 'https://www.kernel.org/doc/html/latest/networking/ip-sysctl.html',
    },
    {
        name: 'net.ipv4.tcp_congestion_control',
        desc: 'Default TCP congestion control algorithm.',
        default: 'cubic',
        presets: {
            bulk: 'bbr',
            rpc: 'cubic',
            web: 'bbr',
            wan: 'bbr',
        },
        range: 'cubic, bbr, reno, htcp (check: sysctl net.ipv4.tcp_available_congestion_control)',
        tags: ['congestion', 'bbr', 'cubic'],
        doc: 'https://www.kernel.org/doc/html/latest/networking/ip-sysctl.html',
    },
    {
        name: 'net.ipv4.tcp_window_scaling',
        desc: 'Enable TCP window scaling (RFC 1323). Required for windows > 65535 bytes.',
        default: '1',
        presets: { bulk: '1', rpc: '1', web: '1', wan: '1' },
        range: '0 (disable) or 1 (enable)',
        tags: ['window', 'rfc1323'],
        doc: 'https://www.kernel.org/doc/html/latest/networking/ip-sysctl.html',
    },
    {
        name: 'net.ipv4.tcp_timestamps',
        desc: 'RFC 1323 timestamps — used for PAWS (protection against wrapped sequence numbers) and RTT measurement.',
        default: '1',
        presets: { bulk: '1', rpc: '1', web: '1', wan: '1' },
        range: '0 (disable), 1 (enable), 2 (enable without ECR)',
        tags: ['rfc1323', 'paws', 'rtt'],
        doc: 'https://www.kernel.org/doc/html/latest/networking/ip-sysctl.html',
    },
    {
        name: 'net.ipv4.tcp_sack',
        desc: 'Selective Acknowledgements (RFC 2018). Allows receiver to inform sender of non-contiguous received segments, improving recovery from multiple losses.',
        default: '1',
        presets: { bulk: '1', rpc: '1', web: '1', wan: '1' },
        range: '0 or 1',
        tags: ['sack', 'loss', 'recovery'],
        doc: 'https://www.kernel.org/doc/html/latest/networking/ip-sysctl.html',
    },
    {
        name: 'net.ipv4.tcp_max_syn_backlog',
        desc: 'Maximum number of SYN packets queued per listening socket before dropping. Increase for high connection-rate servers.',
        default: '1024',
        presets: {
            bulk: '1024',
            rpc: '4096',
            web: '65536',
            wan: '1024',
        },
        range: '128 – 65536 (limited by system memory)',
        tags: ['syn', 'connection', 'backlog'],
        doc: 'https://www.kernel.org/doc/html/latest/networking/ip-sysctl.html',
    },
    {
        name: 'net.core.somaxconn',
        desc: 'Maximum socket listen backlog (accept queue depth). Application must also set listen() backlog >= this value.',
        default: '4096',
        presets: {
            bulk: '4096',
            rpc: '8192',
            web: '65535',
            wan: '4096',
        },
        range: '128 – 65535',
        tags: ['connection', 'backlog', 'accept', 'core'],
        doc: 'https://www.kernel.org/doc/html/latest/networking/ip-sysctl.html',
    },
    {
        name: 'net.ipv4.tcp_tw_reuse',
        desc: 'Allow reuse of TIME_WAIT sockets for new connections when safe (requires timestamps). Reduces port exhaustion under heavy connection churn.',
        default: '2',
        presets: {
            bulk: '2',
            rpc: '1',
            web: '1',
            wan: '2',
        },
        range: '0 (disable), 1 (enable for loopback), 2 (enable for all)',
        tags: ['time_wait', 'port', 'reuse'],
        doc: 'https://www.kernel.org/doc/html/latest/networking/ip-sysctl.html',
    },
    {
        name: 'net.ipv4.tcp_fin_timeout',
        desc: 'Time (seconds) a socket stays in FIN_WAIT_2 state before being forcibly closed. Reduce to reclaim ports faster under high connection rates.',
        default: '60',
        presets: {
            bulk: '60',
            rpc: '15',
            web: '15',
            wan: '60',
        },
        range: '5 – 120 seconds',
        tags: ['fin', 'timeout', 'connection'],
        doc: 'https://www.kernel.org/doc/html/latest/networking/ip-sysctl.html',
    },
];

const PRESETS = {
    default: { label: 'Kernel Defaults', desc: 'Show kernel default values' },
    bulk: { label: 'Bulk File Transfer', desc: 'Large BDP, maximize throughput over high-RTT links' },
    rpc: { label: 'Latency-Sensitive RPC', desc: 'Low-latency datacenter RPCs (Redis, gRPC, etc.)' },
    web: { label: 'High-Connection Web Server', desc: 'High connection rate, many short-lived connections' },
    wan: { label: 'Long-Fat-Pipe WAN', desc: 'High bandwidth × high RTT (satellite, cross-continental)' },
};

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function renderParams() {
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               p.tags.some(t => t.includes(searchQuery));
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    if (!filtered.length) {
        list.innerHTML = '<p style="color:#999">No parameters match your filter.</p>';
        return;
    }

    list.innerHTML = filtered.map((p, idx) => {
        const val = getVal(p);
        const cmd = `sysctl -w ${p.name}=${val}`;
        const tags = p.tags.map(t => `<span class="param-tag">${t}</span>`).join('');
        const changed = currentPreset !== 'default' && val !== p.default;
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                <span class="param-name">${p.name}</span>
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                <div class="param-meta">
                    <span><strong>Default:</strong> ${p.default}</span>
                    <span><strong>Range:</strong> ${p.range}</span>
                </div>
                <div style="margin-top:8px">${tags}</div>
                <div class="copy-block">${cmd} <button class="copy-btn" onclick="copyCmd('${cmd}')">Copy</button></div>
            </div>
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function copyCmd(cmd) {
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function copyAll() {
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    const cmds = filtered.map(p => `sysctl -w ${p.name}=${getVal(p)}`).join('\n');
    copyCmd(cmds);
    alert(`Copied ${filtered.length} sysctl commands to clipboard.`);
}

function toggleCard(event) {
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    const body = card.querySelector('.param-body');
    body.classList.toggle('open');
}

init();
</script>