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如何在没有显示器的情况下，查看 Raspberry Pi 3的 IP 信息（Raspberry Pi 3 ，IP Address）

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IP Address

Any device connected to a Local Area Network is assigned an IP address.

In order to connect to your Raspberry Pi from another machine using SSH or VNC, you need to know the Pi's IP address. This is easy if you have a display connected, and there are a number of methods for finding it remotely from another machine on the network.

Using the Pi with a display

If you boot to the command line instead of the desktop, your IP address should be shown in the last few messages before the login prompt.

Using the terminal (boot to the command line or open a Terminal window from the desktop), simply type hostname -I which will reveal your Pi's IP address.

Using the Pi headless (without a display)

It is possible to find the IP address of your Pi without connecting to a screen using one of the following methods:

Router devices list

In a web browser navigate to your router's IP address e.g. http://192.168.1.1, which is usually printed on a label on your router; this will take you to a control panel. Then log in using your credentials, which is usually also printed on the router or sent to you in the accompanying paperwork. Browse to the list of connected devices or similar (all routers are different), and you should see some devices you recognise. Some devices are detected as PCs, tablets, phones, printers, etc. so you should recognise some and rule them out to figure out which is your Raspberry Pi. Also note the connection type; if your Pi is connected with a wire there should be fewer devices to choose from.

nmap command

The nmap command (Network Mapper) is a free and open-source tool for network discovery, available for Linux, Mac OS, and Windows.

• To install on Linux, install the nmap package e.g. apt-get install nmap.

• To install on Mac OS or Windows, see the nmap.org download page.

To use nmap to scan the devices on your network, you need to know the subnet you are connected to. First find your own IP address, in other words the one of the computer you're using to find your Pi's IP address:

• On Linux, type hostname -I into a terminal window
• On Mac OS, go to System Preferences then Network and select your active network connection to view the IP address
• On Windows, go to the Control Panel, then under Network and Sharing Center, click View network connections, select your active network connection and click View status of this connection to view the IP address

Now you have the IP address of your computer, you will scan the whole subnet for other devices. For example, if your IP address is 192.168.1.5, other devices will be at addresses like 192.168.1.2, 192.168.1.3, 192.168.1.4, etc. The notation of this subnet range is 192.168.1.0/24 (this covers 192.168.1.0 to 192.168.1.255).

Now use the nmap command with the -sn flag (ping scan) on the whole subnet range. This may take a few seconds:

nmap -sn 192.168.1.0/24

Ping scan just pings all the IP addresses to see if they respond. For each device that responds to the ping, the output shows the hostname and IP address like so:

Starting Nmap 6.40 ( http://nmap.org ) at 2014-03-10 12:46 GMT
Nmap scan report for hpprinter (192.168.1.2)
Host is up (0.00044s latency).
Nmap scan report for Gordons-MBP (192.168.1.4)
Host is up (0.0010s latency).
Nmap scan report for ubuntu (192.168.1.5)
Host is up (0.0010s latency).
Nmap scan report for raspberrypi (192.168.1.8)
Host is up (0.0030s latency).
Nmap done: 256 IP addresses (4 hosts up) scanned in 2.41 seconds

Here you can see a device with hostname raspberrypi has IP address 192.168.1.8.

More tools

Also see lsleases

1. 推荐 windows 下，安装 nmap 软件！[下载链接](https://nmap.org/dist/nmap-7.12-setup.exe)

nmap -sn 192.168.1.0/24

实测效果：

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1. https://github.com/raspberrypi/documentation/blob/master/linux/usage/root.md

Root User / Sudo

The Linux operating system is a multi-user operating system which allows multiple users to login and use the computer. To protect the computer (and privacy of other users), users are restricted in what they can do.

Most users are allowed to run most programs, and to save and edit files stored in their own home folder. Normal users are not normally allowed to edit files in other users folders or any of the system files. There is a special user in Linux known as the superuser, which is usually given the username root. The superuser has unrestricted access to the computer and can do almost anything.

Sudo

You will not normally log into to the computer as root, but can instead use the sudo command to provide access as the superuser. If you log into your Raspberry Pi as the pi user then you are logging in as a normal user. You can run commands as the root user by using the sudo command before the program you want to run.

For example if you want to install additional software on Raspbian then you normally use the apt-get tool. To be able to update the list of available software then you need to prefix the apt-get command command with sudo. sudo apt-get update

Find out more about the apt commands

You can also run a superuser shell by using sudo su. When running commands as a superuser there is nothing to protect against mistakes that could damage the system. It is like disabling the safety guards on a machine. It makes it easier to access the insides, but the risk of damage is far greater. It is recommended that you only run commands as the superuser when required and to exit a superuser shell when it is no longer needed.

Who can use Sudo?

It would defeat the point of the security if anyone could just put sudo in front of their commands, so only approved users can use sudo to gain administrator privileges. The pi user is included in the sudoers file. To allow other users to act as a superuser then you could add the user to the sudo group or add them using visudo.

Find out more about users

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1. https://github.com/raspberrypi/documentation/blob/master/remote-access/ssh/README.md

SSH (Secure Shell)

You can remotely gain access to the command line of a Raspberry Pi from another computer on the same network usingssh.

Note you only have access to the command line, not the full desktop environment. For full remote desktop see VNC.

You can enable or disable the SSH server on your Raspberry Pi (it is enabled by default). This is done using raspi-config:

Enter sudo raspi-config in the terminal, then navigate to ssh, hit Enter and select Enable or disable ssh server.

SSH is built into Linux distributions and Mac OS, and a third-party SSH client is available for Windows. See the following guides for using SSH depending on the operating system used by the computer you are connecting from:

• Linux & Mac OS
• Windows

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1. https://github.com/raspberrypi/documentation/blob/master/remote-access/web-server/README.md

Setting up a web server on a Raspberry Pi

You can use a web server on a Raspberry Pi to host a full website (locally on your network or globally on the internet), or just use it to display some information you wish to share to other machines on your network.

Various web servers are available, with different advantages for usage:

• Apache
• NGINX

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1. https://github.com/raspberrypi/documentation/blob/master/remote-access/ssh/sftp.md

SFTP

The SSH File Transfer Protocol is a network protocol that provides file access, file transfer, and file management functionalities over SSH.

By using SFTP you can easily change, browse and edit files on your Raspberry Pi. SFTP is easier to setup than FTP as Raspbian has SSH enabled by default.

FileZilla

Download the latest FileZilla Client version for your operating system from filezilla-project.org.

Launch FileZilla and go to File > Site manager.

Fill in the IP address, user name and password (by default the user name is pi and the password raspberry) of your Raspberry Pi in the dialog and choose SFTP as the protocol.

Click Connect and you will see the home folder of the user.

Ubuntu using Nautilus

Open Nautilus on the client machine

Select File > Connect to Server

Type: SSH
Server: <The Pi's IP address>
Port: 22 (default)
User name: pi (default)
Password: raspberry (default)

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