在 Ubuntu 中配置 SSH 的完整指南
SSH
![](/data/attachment/album/202210/25/102118u33grazpccrvxwdf.jpg)



> 
> 如今 SSH 已成为了登录远程服务器的默认方式。
> 
> 
> 


SSH 的全称是 “<ruby> 安全的 Shell <rt>  Secure Shell </rt></ruby>”，它功能强大、效率高，这个主流的网络协议用于在两个远程终端之间建立连接。让我们不要忘记它名称的“安全”部分，SSH 会加密所有的通信流量，以防止如劫持、窃听等攻击，同时提供不同的身份认证方式和无数个配置选项。


在这份新手指南中，你会学到：


* SSH 的基本概念
* 设置 SSH 服务器（在你想要远程登录的系统上）
* 从客户端（你的电脑）通过 SSH 连接远程服务器


### SSH 的基本概念


在学习配置过程前，让我们先了解一下 SSH 的全部基础概念。


SSH 协议基于<ruby> 客户端-服务器 <rt>  server-client </rt></ruby>（CS）架构。“<ruby> 服务器 <rt>  Server </rt></ruby>”允许“<ruby> 客户端 <rt>  Client </rt></ruby>”通过通信通道进行连接。该信道是经过加密的，信息交换通过 SSH 公私钥进行管理。


![Image credit: SSH](/data/attachment/album/202210/25/102121zsucshrqinghb4zw.png)


[OpenSSH](https://www.openssh.com/) 是在 Linux、BSD 和 Windows 系统上提供 SSH 功能的最流行的开源工具之一。


想要成功配置 SSH，你需要：


* 在作为服务器的机器上部署 SSH 服务器组件，它由 `openssh-server` 包提供。
* 在你远程访问服务器的客户端机器上部署 SSH 客户端组件，它由 `openssh-client` 包提供，大多数 Linux 和 BSD 发行版都已经预装好了。


区分服务器和客户端是十分重要的事情。或许你不想要你的 PC 作为 SSH 服务器，除非你有充分理由希望其他人通过 SSH 连接你的系统。


通常来说，你有一个专用的服务器系统。例如，一个 [运行 Ubuntu 的树莓派](https://itsfoss.com/install-ubuntu-server-raspberry-pi/)。你可以 [启用树莓派的 SSH 服务](https://itsfoss.com/ssh-into-raspberry/)，这样你可以在你 PC 中的终端中，通过 SSH 控制并管理该设备。


有了这些信息，让我们看看如何在 Ubuntu 上设置 SSH 服务器。


### 在 Ubuntu 服务器中配置 SSH


设置 SSH 并不复杂，只需要以下几步。


#### 前提


* 一个在服务器端拥有 `sudo` 权限的用户
* 可以下载所需包的互联网连接
* 在你的网络中至少有另一个系统。可以是局域网中的另一台电脑，远程服务器或者计算机中托管的虚拟机。


**再次强调，在你想要通过 SSH 远程登录的系统上安装 SSH 服务。**


#### 第一步：安装所需包


让我们从打开终端输入一些必要命令开始。


注意，在安装新的包或者软件前，要 [更新你的 Ubuntu 系统](https://itsfoss.com/update-ubuntu/)，以确保运行的是最新版本的程序。



```
sudo apt update && sudo apt upgrade

```

你要运行 SSH 服务器的包由 OpensSSH 的 `openssh-server` 组件提供：



```
sudo apt install openssh-server

```

![](/data/attachment/album/202210/25/102122lbaui9ua741m4o76.png)


#### 第二步：检查服务器状态


当你下载并安装完包后，SSH 服务器应该已经运行了，但是为了确保万无一失我们需要检查一下：



```
service ssh status

```

你还可以使用 `systemctl` 命令：



```
sudo systemctl status ssh

```

你应该会看到这样的结果，其中 `active` 是高亮的。输入 `q` 退出该页面。


![](/data/attachment/album/202210/25/102122pllfzy7yy5y227zl.png)


如果你的结果中 SSH 服务没有运行，使用这个命令运行它：



```
sudo systemctl enable --now ssh

```

#### 第三步：允许 SSH 通过防火墙


Ubuntu 带有名为 [UFW](https://itsfoss.com/set-up-firewall-gufw/)（<ruby> 简单的防火墙 <rt>  Uncomplicated Firewall </rt></ruby>）的防火墙，这是管理网络规则的 `iptables` 的一个接口。如果启动了防火墙，它可能会阻止你连接服务器。


想要配置 UFW 允许你的接入，你需要运行如下命令：



```
sudo ufw allow ssh

```

UFW 的运行状态可以通过运行 `sudo ufw status` 来检查。


现在，我们的 SSH 服务器已经开始运行了，在等待来自客户端的连接。


### 连接远程服务器


你本地的 Linux 系统已经安装了 SSH 客户端。如果没有，你可以在 Ubuntu 中使用如下命令安装：



```
sudo apt install openssh-client

```

要连接你的 Ubuntu 系统，你需要知道它的 IP 地址，然后使用 `ssh` 命令，就像这样：



```
ssh username@address

```

将 **用户名**（`username`）改为你的系统上的实际用户名，并将 **地址**（`address`）改为你服务器的 IP 地址。


如果你 [不知道 IP 地址](https://itsfoss.com/check-ip-address-ubuntu/)，可以在服务器的终端输入 `ip a` 查看结果。应该会看到这样的结果：


![Using “ip a” to find the IP address](/data/attachment/album/202210/25/102123p5vv2mmn5l94gz50.png)


可以看到我的 IP 地址是 `192.168.1.111`。让我们使用 `username@address` 格式进行连接。



```
ssh team@192.168.1.111

```

这是你第一次连接到该 SSH 服务器，它会请求添加主机。输入 `yes` 并回车即可。


![First time connecting to the server](/data/attachment/album/202210/25/102124t9vwtwva6hh9p5hq.png)


SSH 会立即告诉你该主机已经被永久添加了，并要求你输入指定用户的密码，输入密码并再次按回车即可。


![Host added, now type in the password](/data/attachment/album/202210/25/102124xpro252y5s2j22so.png)


瞧，你远程登录了你的 Ubuntu 系统！


![Connected!](/data/attachment/album/202210/25/102125x3bzyv90j333byx3.png)


现在，你可以在远程服务器的终端里和寻常一样工作了。


#### 关闭 SSH 连接


你只需要输入 `exit` 即可关闭连接，它会立马关闭不需要确认。


![Closing the connection with “exit”](/data/attachment/album/202210/25/102126oidf7mxexk0bt6bb.png)


### 在 Ubuntu 中关闭并禁止 SSH


如果你想要停止 SSH 服务，需要运行该命令：



```
sudo systemctl stop ssh

```

该命令会关闭 SSH 服务，直到重启它或者系统重启。想要重启它，输入：



```
sudo systemctl start ssh

```

现在，如果你想要禁止 SSH 跟随系统启动，使用该命令：



```
sudo systemctl disable ssh

```

该命令不会停止当前的 SSH 会话，只会在启动的时候生效。如果你想要它跟随系统启动，输入：



```
sudo systemctl enable ssh

```

#### 其他 SSH 客户端


从 Linux 到 macOS，大多数 \*nix 系统中都有 `ssh` 工具，但这并不是唯一的选项，这里有几个可以在其他操作系统中使用的客户端：


* [PuTTY](https://www.putty.org/) 是一个自由开源的 Windows 系统上的 SSH 客户端。它功能强大并且简单易用。如果你从 Windows 系统上连接你的 Ubuntu 服务器，PuTTY 是最好的选择。（LCTT 译注：切记从官方网站下载。）
* 对安卓用户来说，[JuiceSSH](https://juicessh.com/) 是十分优秀的工具。如果你在旅途中需要一个移动客户端来连接你的 Ubuntu 系统，我强烈建议你试试 JuiceSSH。它已经出现了将近 10 年，并且可以免费使用。
* 最后是 [Termius](https://termius.com/)，它可用于 Linux、Windows、macOS、iOS 和安卓。它有一个免费版本和几个付费选项。如果你运行大量服务器并进行共享连接的团队合作，那么 Termius 对你来说是一个不错的选择。


#### 总结


在这份指导中，你可以在 Ubuntu 系统中设置 SSH 作为服务器，允许来自你电脑的远程安全的连接，便于你通过命令行开展工作。


此，我推荐以下文章：


* [Linux SSH 入门教程](https://linuxhandbook.com/ssh-basics/)
* [利用 SSH 配置文件管理多个 SSH 连接](https://linuxhandbook.com/ssh-config-file/)
* [向 SSH 服务器添加公钥以进行无密码身份验证](https://linuxhandbook.com/add-ssh-public-key-to-server/)
* [保护你的 SSH 服务器的 SSH 加固技巧](https://linuxhandbook.com/ssh-hardening-tips/)


远程工作快乐！




---


via: <https://itsfoss.com/set-up-ssh-ubuntu/>


作者：[Chris Patrick Carias Stas](https://itsfoss.com/author/chris/) 选题：[lujun9972](https://github.com/lujun9972) 译者：[Donkey-Hao](https://github.com/Donkey-Hao) 校对：[wxy](https://github.com/wxy)


本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出


OK
![Warp Terminal](/assets/images/warp-terminal.webp)


![Warp Terminal](/assets/images/warp-terminal.webp)

SSH has become the default method of accessing a remote Linux server these days.

SSH stands for Secure Shell and it’s a powerful, efficient, and popular network protocol used to establish communication between two computers in a remote fashion. And let’s not forget the secure part of its name; SSH encrypts all traffic to prevent attacks like hijacking and eavesdropping while offering different authentication methods and a myriad of configuration options.

In this beginner’s guide, you’ll learn:

- The basic concept of SSH
- Setting up SSH server (on the system you want to access remotely)
- Connecting to remote server via SSH from the client machine (your personal computer)

## The absolute basics of SSH

Before you see any configuration process, it will be better to go through the absolute basic concept of SSH.

The SSH protocol is based on server-client architecture. The “server” allows the “client” to be connected over a communication channel. This channel is encrypted and the exchange is governed by the use of public and private SSH keys.

![ssh diagram](https://itsfoss.com/content/images/wordpress/2021/05/ssh-diagram-800x259.png)

[SSH](https://www.ssh.com/academy/ssh?ref=itsfoss.com)

[OpenSSH](https://www.openssh.com/?ref=itsfoss.com) is one of the most popular open source tools that provides the SSH functionality on Linux, BSD and Windows.

For a successful SSH set up, you need to:

- Have SSH server components on the machine that acts as the server. This is provided by
**openssh-server**package. - Have SSH client component on the machine from where you want to connect to the remote server machine. This is provided by
**openssh-client**package and most Linux and BSD distributions come preinstalled with it.

It is important to keep a distinction between the server and client. You might not want your personal computer to act as SSH server unless you have good reasons where you want others to connect to your system via SSH.

Generally, you have a dedicated system working as the server. For example, a [Raspberry Pi running Ubuntu server](https://itsfoss.com/install-ubuntu-server-raspberry-pi/). You [enable SSH on the Raspberry Pi](https://itsfoss.com/ssh-into-raspberry/) so that you could control and manage the device from your main personal computer using SSH in a terminal.

With that information, let’s see how you can set up a SSH server on Ubuntu.

## Configuring SSH Server on Ubuntu

Setting up SSH is not complicated and just needs a few steps to do it.

### Prerequisites

- A user with
**sudo**privileges on the server machine - Internet connection to download the required packages
- At least another system in your network. It can be another computer on your LAN, a remote server via Internet, or a virtual machine hosted in your computer.


*Again, the SSH server installation should be done on the system that you want to act as a server and to which you want to connect remotely via SSH.*### Step 1: Install required packages

Let’s start by opening a terminal window to enter the necessary commands.

Remember to [update your Ubuntu system](https://itsfoss.com/update-ubuntu/) before installing new packages or software with to make sure that you are running the latest versions.

` sudo apt update && sudo apt upgrade `


The package you need to run SSH Server is provided by openssh-server component from OpenSSH:

`sudo apt install openssh-server`


![Installing openssh-server](https://itsfoss.com/content/images/wordpress/2021/05/ssh-0001.png)

### Step 2: Checking the status of the server

Once the downloading and installation of the package is done the SSH service should be already running, but to be sure we will check it with:

`service ssh status`


You may also use the systemd commands:

`sudo systemctl status ssh`


You should see something like this, with the word Active highlighted. Hit `q`

to return to the command prompt.

![Checking ssh service status](https://itsfoss.com/content/images/wordpress/2021/05/ssh-0002.png)

If in your case the service is not running you will have to activate like this:

`sudo systemctl enable --now ssh`


### Step 3: Allowing SSH through the firewall

Ubuntu comes with a firewall utility called [UFW](https://itsfoss.com/set-up-firewall-gufw/) (UncomplicatedFirewall) which is an interface for **iptables** that in turn manages the network’s rules. If the firewall is active, it may prevent the connection to your SSH Server.

To [configure UFW](https://itsfoss.com/ufw-ubuntu/) so that it allows the wanted access, you need to run the following command:

`sudo ufw allow ssh`


The status of UFW can be checked running `sudo ufw status`

.

At this time our SSH Server is up and running, just waiting for a connection from a client.

## Connecting to the remote system from your local machine

Your local Linux system should already have an SSH client installed. If not, you may always install it using the following command on Ubuntu:

`sudo apt install openssh-client`


To connect to your Ubuntu system you need to know the IP address of the computer and use the `ssh`

command, like this:

`ssh username@address `


Change **username** to your actual user in the system and **address** to the IP address of your Ubuntu machine.

If you don’t [know the IP address of your computer](https://itsfoss.com/check-ip-address-ubuntu/) you can type `ip a`

in the terminal of the server and check the output. You should have something like this:

![ssh find ip](https://itsfoss.com/content/images/wordpress/2021/05/ssh-find-ip-800x341.png)

As can be seen here my IP address is **192.168.1.111**. Let’s try connecting using the **username@address** format.

`ssh `[[email protected]](/cdn-cgi/l/email-protection)


The first time you connect to a SSH server, it will ask for permission to add the host. Type `yes`

and hit Enter to continue.

![Connecting for the first time with SSH](https://itsfoss.com/content/images/wordpress/2021/05/ssh-0004.png)

Immediately SSH tells you that the host was permanently added and then asks for the password assigned to the username. Type in the password and hit Enter one more time.

![SSH asking for password](https://itsfoss.com/content/images/wordpress/2021/05/ssh-0005.png)

And voila! You will be logged into your Ubuntu system remotely!

![Connected with SSH](https://itsfoss.com/content/images/wordpress/2021/05/ssh-0006-800x322.png)

Now you can work in your remote system’s terminal as normal.

## Closing the SSH connection

To close the connection you just need to type `exit`

and it will close it at once, without asking for confirmation.

![Closing the connection with exit](https://itsfoss.com/content/images/wordpress/2021/05/ssh-0007.png)

## Stopping and Disabling SSH in Ubuntu

If you want to stop SSH service you will need this command:

`sudo systemctl stop ssh`


This will stop the service until you restart it or until the system is rebooted. To restart it, type:

`sudo systemctl start ssh`


Now, if you want to disable it from starting during system boot, use this:

`sudo systemctl disable ssh`


This won’t stop the service from running during the current session, just from loading during startup. If you want to let it start again during system boot, type:

`sudo systemctl enable ssh`


## Other SSH clients

The tool ssh is included in most *nix systems, from Linux to macOS, but those are not the only options in existence, here are a couple of clients that can be used from other operating systems:

[PuTTY](https://www.putty.org/?ref=itsfoss.com)is a free and open source SSH client which is hugely popular among Windows users. You can also[install PuTTY on Ubuntu](https://itsfoss.com/putty-linux/). It’s full of features and very easy to use. If you are connecting to your Ubuntu machine from a Windows station, PuTTY is a great option.[JuiceSSH](https://juicessh.com/?ref=itsfoss.com)is an amazing tool for Android users. If you are on the go and need a mobile client to connect to your Ubuntu system, I amply recommend giving JuiceSSH a go. It’s been around for almost 10 years and it’s free to use.- And finally,
[Termius](https://termius.com/?ref=itsfoss.com)is available for Linux, Windows, macOS, iOS, and Android. It has a free tier version and also several premium options. If you are running a lot of servers and working with teams sharing connections then Termius is a good option for you.

## Wrapping Up

With these instructions, you can set up SSH as a server service in our Ubuntu systems to be able to connect remotely and securely to your computer in order to work with the command line and perform any required task.

Our other website, Linux Handbook, has various informational articles on SSH. From here, I recommend reading the following:

[Getting started with SSH on Linux](https://linuxhandbook.com/ssh-basics/?ref=itsfoss.com)[Using SSH Config file to manage multiple SSH connections](https://linuxhandbook.com/ssh-config-file/?ref=itsfoss.com)[Adding public key to SSH server for password less authentication](https://linuxhandbook.com/add-ssh-public-key-to-server/?ref=itsfoss.com)[SSH hardening tips](https://linuxhandbook.com/ssh-hardening-tips/?ref=itsfoss.com)to secure your SSH server

If you find it overwhelming, [Linux Handbook has a premium video course that explains SSH for beginners](https://linuxhandbook.com/sshcourse/?ref=itsfoss.com) along with hands-on labs to follow. This will give you a more streamlined knowledge of the topic.

Happy remote working!