Mac 下使用 SSH 連接遠程 Linux 服務器

首先 Mac 不像 Windows 需要類似 XShell 這樣的客戶端進行SSH連接，直接使用終端即可。

一、首先查看 IP 地址

我這裏是使用的 Ubuntu 18.04 的模擬器。

1. 輸入命令：ifconfig
   

2. 需要安裝 net-tools：apt install net-tools
   

3. 安裝成功後，再次 ifconfig
   

二、ssh 登錄

1. ssh 登錄 root 用戶
   使用 ssh root@IP地址 或者 ssh -p 22 root@IP地址 命令
   出現錯誤：

   ➜  ~ ssh [email protected]
   ssh: connect to host 192.168.139.129 port 22: Connection refused
   ➜  ~ ssh -p 22 [email protected]
   ssh: connect to host 192.168.139.129 port 22: Connection refused
   

2. 檢查服務端 ssh 服務是否開啓

   ps -e | grep sshd
   

   沒有找到 sshd ，說明 ssh 服務沒有啓動，需要開啓 ssh 服務。

三、啓動服務器的 ssh

1. 開啓 ssh 服務

service ssh start

2. 更新源列表

apt-get update

3. 安裝 openssh-server

apt-get install openssh-server

4. 再次查看 ssh 服務是否啓動

四、ssh 登錄

1. 連接 root 用戶

➜  ~ ssh [email protected]      
The authenticity of host '192.168.139.129 (192.168.139.129)' can't be established.
ECDSA key fingerprint is SHA256:rVB8kHFOI0hCUyibvY6w5TfDF6I+5z0qG2jcVIxi94c.
Are you sure you want to continue connecting (yes/no)? yes

2. 輸入 root 用戶密碼

Warning: Permanently added '192.168.139.129' (ECDSA) to the list of known hosts.
[email protected]'s password: 

3. 權限被拒絕

Permission denied, please try again.

這種情況，很大的可能是由於服務器默認禁止 root 用戶進行 ssh 遠程登錄。

4. 嘗試普通用戶登錄，排除配置問題

➜  ~ ssh [email protected]
[email protected]'s password: 

5. 輸入用戶密碼，普通用戶登錄成功。

Welcome to Ubuntu 18.04.2 LTS (GNU/Linux 4.18.0-17-generic x86_64)

 * Documentation:  https://help.ubuntu.com
 * Management:     https://landscape.canonical.com
 * Support:        https://ubuntu.com/advantage


 * Canonical Livepatch is available for installation.
   - Reduce system reboots and improve kernel security. Activate at:
     https://ubuntu.com/livepatch

167 個可升級軟件包。
75 個安全更新。

Your Hardware Enablement Stack (HWE) is supported until April 2023.

The programs included with the Ubuntu system are free software;
the exact distribution terms for each program are described in the
individual files in /usr/share/doc/*/copyright.

Ubuntu comes with ABSOLUTELY NO WARRANTY, to the extent permitted by
applicable law.

ff@FF-VM:~$ 

到這裏就基本確定了就是，服務器禁止 root 用戶進行 ssh 遠程登錄了。

五、允許 root 用戶 ssh 登錄

1. 修改 sshd_config
   注意，安裝了 openssh 纔會有這個文件，如果文件不存在請檢查是否安裝了 openssh。

vim /etc/ssh/sshd_config

2. 配置 PermitRootLogin

• 檢查是否有 PermitRootLogin
• 存在 PermitRootLogin ... 的話(...代表任何語句)，全部修改爲 PermitRootLogin yes
• 不存在 PermitRootLogin 的話，增加 PermitRootLogin yes

不過這裏有問題，正常情況下 PermitRootLogin 應該也是黃色高亮的。
我嘗試了多次，還是不能高亮，不管了先保存。

3. 重啓 ssh 服務

/etc/init.d/ssh restart

4. 連接 root 用戶

➜  ~ ssh [email protected]      
[email protected]'s password: 
Permission denied, please try again.

依然權限被拒絕，說明配置 PermitRootLogin yes 沒有生效。

六、重新安裝 openssh-server

大多數情況下，完成上一步就可以完成登錄了，是不需要該步驟的。

1. 卸載 openssh-server

apt-get purge openssh-server

2. 刪除 sshd_config

rm /etc/ssh/sshd_config

3. 更新源列表

apt-get update

4. 安裝 openssh-server

apt-get install openssh-server

5. 打開 sshd_config

vim /etc/ssh/sshd_config

6. 配置 PermitRootLogin

7. 啓動 ssh 服務

/etc/init.d/ssh start

七、 ssh 登錄

連接 root 用戶

➜  ~ ssh [email protected]
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@    WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED!     @
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!
Someone could be eavesdropping on you right now (man-in-the-middle attack)!
It is also possible that a host key has just been changed.
The fingerprint for the ECDSA key sent by the remote host is
SHA256:5devwrE/cIsO8P0l9nc7zQ+xxKRO5BIUDZ1tjd8BB+0.
Please contact your system administrator.
Add correct host key in /Users/ff/.ssh/known_hosts to get rid of this message.
Offending ECDSA key in /Users/ff/.ssh/known_hosts:5
ECDSA host key for 192.168.139.129 has changed and you have requested strict checking.
Host key verification failed.

出現錯誤的原因是，重裝了 openssh-server ，服務器的公鑰發生了變化導致的錯誤。

SSH 服務是通過公鑰和私鑰來進行連接的，它會把每個曾經訪問過計算機或服務器的公鑰，記錄在 known_hosts 中，當下次訪問曾經訪問過的計算機或服務器時，SSH 就會覈對公鑰，如果和上次記錄的不同，OpenSSH 會發出警告。

八、修改客戶端 known_hosts 文件

根據提示進行修改

Add correct host key in /Users/ff/.ssh/known_hosts to get rid of this message.

1. 進入 known_hosts

➜  ~ vim /Users/ff/.ssh/known_hosts

2. 找到以 192.168.139.129 起始的行，將正行刪除

192.168.139.129 ecdsa-sha2-nistp256 ...省略

九、ssh 登錄

1. 連接 root 用戶

➜  ~ ssh [email protected]      
The authenticity of host '192.168.139.129 (192.168.139.129)' can't be established.
ECDSA key fingerprint is SHA256:5devwrE/cIsO8P0l9nc7zQ+xxKRO5BIUDZ1tjd8BB+0.
Are you sure you want to continue connecting (yes/no)? yes

2. 輸入 root 用戶密碼

Warning: Permanently added '192.168.139.129' (ECDSA) to the list of known hosts.
[email protected]'s password: 

3. root 用戶登錄成功

Welcome to Ubuntu 18.04.2 LTS (GNU/Linux 4.18.0-20-generic x86_64)

 * Documentation:  https://help.ubuntu.com
 * Management:     https://landscape.canonical.com
 * Support:        https://ubuntu.com/advantage


 * Canonical Livepatch is available for installation.
   - Reduce system reboots and improve kernel security. Activate at:
     https://ubuntu.com/livepatch

0 個可升級軟件包。
0 個安全更新。

Your Hardware Enablement Stack (HWE) is supported until April 2023.

The programs included with the Ubuntu system are free software;
the exact distribution terms for each program are described in the
individual files in /usr/share/doc/*/copyright.

Ubuntu comes with ABSOLUTELY NO WARRANTY, to the extent permitted by
applicable law.

root@FF-VM:~#