> For the complete documentation index, see [llms.txt](https://hacking-notes.jord4n.pro/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://hacking-notes.jord4n.pro/zh/hacking-tools/calculators/subnetting-calculator.md).

# 子网划分计算器

搜索类似以下的 CIDR 前缀： `/24`, `/27`，或 `/30` 即可获取子网掩码、通配符掩码、地址总数、可用主机范围大小和块大小。

## CIDR 查找器

<table data-view="cards" data-full-width="true" data-search="true"><thead><tr><th>CIDR</th><th>子网掩码</th><th>通配符掩码</th><th>IP 总数</th><th>可用主机数</th><th>块大小</th><th>常见用途</th></tr></thead><tbody><tr><td><code>/0</code></td><td>0.0.0.0</td><td>255.255.255.255</td><td>4,294,967,296</td><td>4,294,967,294</td><td>第 1 个八位组为 256</td><td>默认路由</td></tr><tr><td><code>/8</code></td><td>255.0.0.0</td><td>0.255.255.255</td><td>16,777,216</td><td>16,777,214</td><td>第 1 个八位组为 1</td><td>超大网络</td></tr><tr><td><code>/9</code></td><td>255.128.0.0</td><td>0.127.255.255</td><td>8,388,608</td><td>8,388,606</td><td>第二个八位组为 128</td><td>大型划分</td></tr><tr><td><code>/10</code></td><td>255.192.0.0</td><td>0.63.255.255</td><td>4,194,304</td><td>4,194,302</td><td>第二个八位组为 64</td><td>大型划分</td></tr><tr><td><code>/11</code></td><td>255.224.0.0</td><td>0.31.255.255</td><td>2,097,152</td><td>2,097,150</td><td>第二个八位组为 32</td><td>大型划分</td></tr><tr><td><code>/12</code></td><td>255.240.0.0</td><td>0.15.255.255</td><td>1,048,576</td><td>1,048,574</td><td>第二个八位组为 16</td><td>RFC1918 172.16.0.0/12</td></tr><tr><td><code>/13</code></td><td>255.248.0.0</td><td>0.7.255.255</td><td>524,288</td><td>524,286</td><td>第二个八位组为 8</td><td>大型企业</td></tr><tr><td><code>/14</code></td><td>255.252.0.0</td><td>0.3.255.255</td><td>262,144</td><td>262,142</td><td>第二个八位组为 4</td><td>大型企业</td></tr><tr><td><code>/15</code></td><td>255.254.0.0</td><td>0.1.255.255</td><td>131,072</td><td>131,070</td><td>第二个八位组为 2</td><td>大型企业</td></tr><tr><td><code>/16</code></td><td>255.255.0.0</td><td>0.0.255.255</td><td>65,536</td><td>65,534</td><td>第二个八位组为 1</td><td>大型局域网</td></tr><tr><td><code>/17</code></td><td>255.255.128.0</td><td>0.0.127.255</td><td>32,768</td><td>32,766</td><td>第三个八位组为 128</td><td>大型 VLAN 块</td></tr><tr><td><code>/18</code></td><td>255.255.192.0</td><td>0.0.63.255</td><td>16,384</td><td>16,382</td><td>第三个八位组为 64</td><td>大型 VLAN 块</td></tr><tr><td><code>/19</code></td><td>255.255.224.0</td><td>0.0.31.255</td><td>8,192</td><td>8,190</td><td>第三个八位组为 32</td><td>大型 VLAN 块</td></tr><tr><td><code>/20</code></td><td>255.255.240.0</td><td>0.0.15.255</td><td>4,096</td><td>4,094</td><td>第三个八位组为 16</td><td>中型网络</td></tr><tr><td><code>/21</code></td><td>255.255.248.0</td><td>0.0.7.255</td><td>2,048</td><td>2,046</td><td>第三个八位组为 8</td><td>中型网络</td></tr><tr><td><code>/22</code></td><td>255.255.252.0</td><td>0.0.3.255</td><td>1,024</td><td>1,022</td><td>第三个八位组为 4</td><td>中型网络</td></tr><tr><td><code>/23</code></td><td>255.255.254.0</td><td>0.0.1.255</td><td>512</td><td>510</td><td>第三个八位组为 2</td><td>两个 /24 网络</td></tr><tr><td><code>/24</code></td><td>255.255.255.0</td><td>0.0.0.255</td><td>256</td><td>254</td><td>第三个八位组为 1</td><td>常见局域网</td></tr><tr><td><code>/25</code></td><td>255.255.255.128</td><td>0.0.0.127</td><td>128</td><td>126</td><td>第四个八位组为 128</td><td>半个 /24</td></tr><tr><td><code>/26</code></td><td>255.255.255.192</td><td>0.0.0.63</td><td>64</td><td>62</td><td>第四个八位组为 64</td><td>小型 VLAN</td></tr><tr><td><code>/27</code></td><td>255.255.255.224</td><td>0.0.0.31</td><td>32</td><td>30</td><td>第四个八位组为 32</td><td>小型子网</td></tr><tr><td><code>/28</code></td><td>255.255.255.240</td><td>0.0.0.15</td><td>16</td><td>14</td><td>第四个八位组为 16</td><td>超小子网</td></tr><tr><td><code>/29</code></td><td>255.255.255.248</td><td>0.0.0.7</td><td>8</td><td>6</td><td>第四个八位组为 8</td><td>小型路由段</td></tr><tr><td><code>/30</code></td><td>255.255.255.252</td><td>0.0.0.3</td><td>4</td><td>2</td><td>第四个八位组为 4</td><td>点对点</td></tr><tr><td><code>/31</code></td><td>255.255.255.254</td><td>0.0.0.1</td><td>2</td><td>点对点使用 2</td><td>第四个八位组为 2</td><td>点对点链路</td></tr><tr><td><code>/32</code></td><td>255.255.255.255</td><td>0.0.0.0</td><td>1</td><td>1 主机路由</td><td>1 个 IP</td><td>单主机</td></tr></tbody></table>

## 手动计算

| 步长     | 公式                             |
| ------ | ------------------------------ |
| IP 总数  | `2^(32 - CIDR)`                |
| 可用主机数  | `总数 - 2`，除非 `/31` 和 `/32` 特殊情况 |
| 块大小    | `256 - 相关掩码八位组`                |
| 网络地址   | 将相关八位组向下取整到最近的块                |
| 广播地址   | 下一个网络减 1                       |
| 第一个主机  | 网络地址加 1                        |
| 最后一个主机 | 广播地址减 1                        |

## 示例

<table data-view="cards" data-full-width="true" data-search="true"><thead><tr><th>IP/CIDR</th><th>网络</th><th>第一个主机</th><th>最后一个主机</th><th>广播地址</th><th>备注</th></tr></thead><tbody><tr><td><code>192.168.1.37/27</code></td><td>192.168.1.32</td><td>192.168.1.33</td><td>192.168.1.62</td><td>192.168.1.63</td><td>/27 块每次递增 32。</td></tr><tr><td><code>10.10.10.10/30</code></td><td>10.10.10.8</td><td>10.10.10.9</td><td>10.10.10.10</td><td>10.10.10.11</td><td>/30 块每次递增 4。</td></tr><tr><td><code>172.16.44.201/26</code></td><td>172.16.44.192</td><td>172.16.44.193</td><td>172.16.44.254</td><td>172.16.44.255</td><td>/26 块每次递增 64。</td></tr><tr><td><code>192.168.56.90/28</code></td><td>192.168.56.80</td><td>192.168.56.81</td><td>192.168.56.94</td><td>192.168.56.95</td><td>/28 块每次递增 16。</td></tr></tbody></table>

## 常用范围

| 范围                            | CIDR             | 使用   |
| ----------------------------- | ---------------- | ---- |
| 10.0.0.0 - 10.255.255.255     | `10.0.0.0/8`     | 私有网络 |
| 172.16.0.0 - 172.31.255.255   | `172.16.0.0/12`  | 私有网络 |
| 192.168.0.0 - 192.168.255.255 | `192.168.0.0/16` | 私有网络 |
| 127.0.0.0 - 127.255.255.255   | `127.0.0.0/8`    | 回环   |
| 169.254.0.0 - 169.254.255.255 | `169.254.0.0/16` | 链路本地 |
| 224.0.0.0 - 239.255.255.255   | `224.0.0.0/4`    | 组播   |


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