> 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

用于 CIDR、子网掩码、通配掩码、主机数量、块大小、私有地址段和快速子网计算示例的子网划分计算器。

搜索诸如 `/24`, `/27`或 `/30` 的 CIDR 前缀，以获取子网掩码、通配掩码、地址数量、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2个八位组为128</td><td>大规模拆分</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2个八位组为64</td><td>大规模拆分</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2个八位组为32</td><td>大规模拆分</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2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2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2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2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2个八位组为1</td><td>大型 LAN</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3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3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3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3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3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3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3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3个八位组为1</td><td>常见 LAN</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4个八位组为128</td><td>/24 的一半</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4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4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4个八位组为16</td><td>极小子网</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4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4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>点对点为2</td><td>第4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 条主机路由</td><td>1 个 IP</td><td>单一主机</td></tr></tbody></table>

## 手动计算

| 步进     | 公式                             |
| ------ | ------------------------------ |
| IP 总数  | `2^(32 - CIDR)`                |
| 可用主机数  | `总数 - 2`，除外 `/31` 和 `/32` 特殊情况 |
| 块大小    | `256 - 关键掩码八位组`                |
| 网络地址   | 将关键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                         |

## 示例演练

<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</th><th>说明</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 块按 32 递增。</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 块按 4 递增。</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 块按 64 递增。</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 块按 16 递增。</td></tr></tbody></table>

## 有用范围

| 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   |


---

# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.

## Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation by asking a question.

Perform an HTTP GET request on the following URL with the `ask` and `goal` query parameters:

```
GET https://hacking-notes.jord4n.pro/zh/hacking-tools/calculators/subnetting-calculator.md?ask=<question>&goal=<user_goal>
```

`ask` is the immediate question: it should be specific, self-contained, and written in natural language.
`goal` is what the user is ultimately trying to achieve, the reason they need the answer. Sharing it helps GitBook give you a better, more relevant answer. A goal is most helpful when it describes the outcome the user wants rather than restating the question. For example, with `ask=how do I create an API token`, a goal like `automate deployments from our CI pipeline` lets GitBook tailor the answer to that use case.

The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.