> For the complete documentation index, see [llms.txt](https://www.axisnow.io/zh/docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://www.axisnow.io/zh/docs/edge/policies/real-ip/toa.md).

# 安装 TOA 内核模块

在源站安装 TOA 内核模块以透明获取真实客户端 IP

TOA（TCP Option Address）把真实客户端 IP 和端口放在 TCP 选项中传给源站。源站加载 TOA 内核模块后，应用通过 `getpeername` 等常规接口获得的即为真实客户端地址，无需改动程序，也不需要源站软件支持 Proxy Protocol。模块使用 [ucloud/ucloud-toa](https://github.com/ucloud/ucloud-toa)，支持 2.6.32 到当前主线内核。

## 前提 <a href="#prerequisites" id="prerequisites"></a>

* 源站为 Linux；只对 TCP 有效，只传递 IPv4 客户端地址，源站监听 IPv6 地址（如 Go 默认的 `::`）时获得的是 IPv4 映射地址。
* 编译需要与运行内核完全一致版本的内核头文件；内核升级后要重新编译并加载。
* TCP 选项没有防篡改保护。只让边缘的流量到达源站端口，否则直连源站的客户端可以伪造来源地址。

## 安装 <a href="#install" id="install"></a>

1. 安装编译工具和内核头文件：

```bash
# CentOS / RHEL
sudo yum install -y gcc make kernel-devel-$(uname -r)
# Ubuntu / Debian
sudo apt-get install -y gcc make linux-headers-$(uname -r)
# SUSE
sudo zypper install gcc make kernel-default-devel
```

2. 获取源码并编译，得到 `toa.ko`：

```bash
git clone https://github.com/ucloud/ucloud-toa.git
cd ucloud-toa
make
```

提示 `config_retpoline=y but not supported by the compiler` 说明 gcc 版本过低，升级后重试。

3. 加载并确认：

```bash
sudo insmod toa.ko
lsmod | grep toa
dmesg | grep -i toa     # 看到 TOA: toa loaded
```

4. 开机自动加载。把模块放进内核模块目录并登记，然后用 `modprobe` 确认登记成功：

```bash
sudo mkdir -p /lib/modules/$(uname -r)/extra
sudo cp toa.ko /lib/modules/$(uname -r)/extra/
sudo depmod -a
echo toa | sudo tee /etc/modules-load.d/toa.conf
sudo rmmod toa && sudo modprobe toa
```

源站内核需要定期升级时，第 2 到 4 步可改用 DKMS，内核升级后自动重新编译并加载：

```bash
sudo cp -r ucloud-toa /usr/src/toa-1.0.0
sudo dkms add -m toa -v 1.0.0
sudo dkms install -m toa -v 1.0.0
echo toa | sudo tee /etc/modules-load.d/toa.conf
```

## 验证 <a href="#verify" id="verify"></a>

在 AxisNow 的 TCP 转发端点上把[转发方式设为 TOA](/zh/docs/edge/policies/real-ip/use-cases.md#tcp)，从外部访问一次，然后在源站查看模块计数，`syn_recv_sock_toa` 和 `getname_toa_ok` 随访问增长即为生效：

```bash
cat /proc/net/toa_stats
```

应用日志里的来源地址此时应为客户端真实 IP。`ss`、`netstat` 显示的仍是边缘地址，模块只改变应用通过 `getpeername` 获得的结果。

## 卸载 <a href="#uninstall" id="uninstall"></a>

```bash
sudo rmmod toa
sudo rm /etc/modules-load.d/toa.conf /lib/modules/$(uname -r)/extra/toa.ko
sudo depmod -a
```


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