> For the complete documentation index, see [llms.txt](https://anjia1.gitbook.io/web/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://anjia1.gitbook.io/web/engineering/more/ssh.md).

# ssh

相关目录及文件，如下：

```shell
~/.ssh » ll
total 64
-rw-------  1 username  staff   419B Mar 29 23: 31 id_ed25519
-rw-r--r--  1 username  staff   106B Mar 29 23: 31 id_ed25519.pub
-rw-------  1 username  staff   1.6K May 27  2016  id_rsa
-rw-r--r--  1 username  staff   412B May 27  2016  id_rsa.pub
-rw-r--r--  1 username  staff    15K Mar 29 23: 52 known_hosts
```

## known\_hosts

known\_hosts 文件，记录我们访问过的计算机的 public key。如下：

```bash
~/.ssh » cat known_hosts
x.x.x.x ssh-rsa AAAAB3...Nw==
x.x.x.x ecdsa-sha2-nistp256 AAAAE2...7B/w=
domainname.com ssh-ed25519 AAAAC3...fVov
```

当我们用 ssh 连接到一个新服务器时，ssh 会让我们确认服务器的信息（IP/domain-name, public key），确认了之后就会被写到 known\_hosts 里。

```sh
~/GitHub/project-name(master) » git push
The authenticity of host 'github.com (x.x.x.x)' can't be established.
ECDSA key fingerprint is SHA256:p2...c98/R1...u3/Li...M.
Are you sure you want to continue connecting (yes/no/[fingerprint])? yes
Warning: Permanently added 'github.com,x.x.x.x' (ECDSA) to the list of known hosts.
```

此时再看 known\_hosts 文件，最后一行会新增如下内容：

```bash
github.com,x.x.x.x ecdsa-sha2-nistp256 AAAAE2...dT/y..B/++T...g=
```

以后再连接到这个服务器时，如果信息变了（通常是 public key 变了），就会提示我们服务器信息变了。此时，我们可以将其从 known\_hosts 里删除，然后重新确认。

## 秘钥对

制作 private key 和 public key：

```bash
ssh-keygen  # 建立秘钥对
ssh-keygen -t rsa -b 4096 -C "your_email@example.com"
ssh-keygen -t ed25519 -C "your_email@example.com"
```

```bash
# Github 支持的 public keys 格式
id_rsa.pub
id_ecdsa.pub
id_ed25519.pub
```

## 其它

authorized\_keys 可以让两个 linux 机器之间使用 ssh 不需要用户名和密码

把客户端 public key 上传到服务器，并将其添加到 authorized\_keys

在服务器上安装公钥 `>> authorized_keys`