How to List All Connected SSH Sessions on Linux (2024)

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LinuxOpen SourceOperating System

Introduction

Secure Shell (SSH) is a commonly used protocol for secure remote access to Linux servers. When multiple users are connected to a Linux server via SSH, it can be useful to list all connected SSH sessions for administrative or monitoring purposes. In this article, we will discuss how to list all connected SSH sessions on Linux using various command line tools.

List of SSH sessions connected with the who command

The who command is a simple and widely available command-line tool for listing logged in users on a Linux system. To list all connected SSH sessions, you can use the “who -a” command. The -a option shows all users, including those who are not logged in through the system console. The result will show your username, terminal, and login date and time.

$ who -aroot pts/0 2020-12-19 14:20 (10.0.0.1)user1 pts/1 2020-12-19 15:25 (10.0.0.2)user2 pts/2 2020-12-19 14:30 (10.0.0.3)

In this example, the output shows that there are three users currently connected: "root", "user1" and "user2", along with the endpoint they connected to and the IP addresses they connected from.

List of SSH sessions connected with the w command

Another command-line tool that can be used to list connected SSH sessions is “w”. This command displays information about users currently logged on to the system, and also displays the process each user is running. To list all connected SSH sessions, you can use the “w -h” command, which omits the header and shows only the process.

$ w -hroot pts/0 14:20 2.00s 0.00s ssh 10.0.0.1user1 pts/1 14:25 1.00s 0.00s ssh 10.0.0.2user2 pts/2 14:30 1.00s 0.00s ssh 10.0.0.3

In this example, the output shows that the three users are currently connected, the terminal they are connected to, and the IP addresses they are connecting from.

List of SSH sessions connected with the last command

The last command is used to display users who have recently logged on to the system. This command can also be used to list connected SSH sessions using the latest “-i” command.

$ last -iroot pts/0 10.0.0.1 Sun Dec 19 14:20 - 14:25 (00:05)user1 pts/1 10.0.0.2 Sun Dec 19 14:25 - 14:30 (00:05)user2 pts/2 10.0.0.3 Sun Dec 19 14:30 - 14:35 (00:05)

In this example, the output shows the three users currently connected, the endpoint they connected to, the IP addresses they connected from, and the length of their session.

List of SSH sessions connected with the who -u command

You can also use the “who -u” command to list all connected SSH sessions. This command displays the user, terminal, and login date and time.

$ who -uroot pts/0 2020-12-19 14:20 (10.0.0.1)user1 pts/1 2020-12-19 14:25 (10.0.0.2)user2 pts/2 2020-12-19 14:30 (10.0.0.3)

The “-u” option shows users and their idle time, but does not show IP addresses. So, if IP information is important to you, you can combine this command with the “-i” option which will show the IP addresses.

$ who -u -iroot pts/0 2020-12-19 14:20 (10.0.0.1) . . . . . . . . . . . . . . . user1 pts/1 2020-12-19 14:25 (10.0.0.2) . . . . . . . . . . . . . . . user2 pts/2 2020-12-19 14:30 (10.0.0.3) . . . . . . . . . . . . . . .

List of SSH sessions connected with the ss command

Another command that can be used to list connected SSH sessions is ss. This command is similar to netstat but more efficient and is used to dump socket statistics. To list all connected SSH sessions, you can use the “ss -t -a” command.

$ ss -t -a | grep sshtcp ESTAB 0 0 10.0.0.1:ssh 10.0.0.1:46754 users:(("sshd",pid=9987,fd=3))tcp ESTAB 0 0 10.0.0.2:ssh 10.0.0.2:47754 users:(("sshd",pid=9987,fd=3))tcp ESTAB 0 0 10.0.0.3:ssh 10.0.0.3:48754 users:(("sshd",pid=9987,fd=3))

The “-t” option shows only TCP connections and the “-a” option shows all sockets. The grep command is used to filter the output and shows only ssh connections.

Conclusion

In this article, we have discussed several command-line tools for listing connected SSH sessions on Linux. Each command has its own specific options and output format, so it's up to you to choose the one that best suits your needs. It is always recommended to consult the man pages of each command before using it, to ensure that you are using the correct options and getting the expected result.

Pradeep Jhuriya

Updated on: 20-Jan-2023

31K+ Views

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FAQs

How to List All Connected SSH Sessions on Linux? ›

To list all connected SSH sessions, you can use the “who -a” command. The -a option shows all users, including those who are not logged in through the system console. The result will show your username, terminal, and login date and time.

Read On ›

How to list all SSH keys in Linux? ›

Checking for existing SSH keys

Open Terminal .
Enter ls -al ~/.ssh to see if existing SSH keys are present. $ ls -al ~/.ssh # Lists the files in your .ssh directory, if they exist.
Check the directory listing to see if you already have a public SSH key. ...
Either generate a new SSH key or upload an existing key.

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How to check SSH connectivity in Linux? ›

To Test the SSH Setup on a Host

From another host, use SSH to log in into the host that you are testing as the SSH user. $ ssh -l user-name host-name user-name. The user name for the SSH user's account on the host. ...
In response to the prompt, type your password. If this step succeeds, your setup of SSH is complete.

How to check SSH logins in Linux? ›

To view the SSH logs in /var/log/auth. log , you can use common text file viewing commands such as cat , less , or tail .

See Details ›

How do I see how many active connections I have in Linux? ›

The ss command is probably the best tool to query statistics for network connections, including the total number of open connections.

Find Out More ›

How do I list all SSH sessions in Linux? ›

The who command is a simple and widely available command-line tool for listing logged in users on a Linux system. To list all connected SSH sessions, you can use the “who -a” command. The -a option shows all users, including those who are not logged in through the system console.

Tell Me More ›

How to see all files in SSH? ›

How to list the account Files and Directories with SSH?

ls. ...
ls -a. ...
ls -l. ...
ls -R. ...
ls -t. ...
ls -la – Lists all files and folders (including hidden ones) with additional information.
ls -hl – Lists all files and folder in human readable format which -h standards for.

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How to check SSH keys in terminal? ›

Checking of existing SSH keys

Whether you use macOS or Linux, open your Terminal application.
Run cd ~/. ssh/ in your Terminal.
If the folder exists, run ls and check if a pair of key exists : id_ed25519 and id_ed25519. pub. Using id_rsa and id_rsa. pub is fine too. We are just advocating the use of ed25519.

Feb 12, 2024

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How do you check if SSH is configured or not? ›

Check whether you have enabled SSH

To check whether the SSH server has been installed, run the following command: systemctl -t service|grep sshd.
If the SSH isn't installed on your node, run the following commands to install and start the SSH server. yum install openssh-server. systemctl enable sshd. systemctl start sshd.

Feb 1, 2024

How to check ssh-agent in Linux? ›

Running ssh-add -l will display all keys currently known to your agent. If the list is empty, you have an ssh-agent running, but no keys currently unlocked. If you receive an error message like Could not open a connection to your authentication agent. you need to start the agent first (see above).

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How do I list all SSH login attempts? ›

The basic command to list all SSH failed login attempts is # grep "Failed password" /var/log/auth. log. The same can be achieved by executing the cat command # cat /var/log/auth. log | grep "Failed password".

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How do I view connection logs in Linux? ›

How to View Linux Logs? Like any other OS, you can use certain commands to see Linux log files. First, let's switch to the directory where you can find Linux system logs with the command cd /var/log. Then, you can type ls to see the logs stored under this directory.

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How to get list of users logged into a server in Linux? ›

Listing users in a Linux system is crucial for server administrations. You can do so by outputting the /etc/passwd file's content using the cat command. It will print all usernames with details like their ID, default home directory, and login shell path.

Get More Info Here ›

How do I list all connections in Linux? ›

To list all the network connections that are currently open on a Linux system, one can utilize the lsof (list open files) command. Lsof is a powerful and versatile tool that provides detailed information about files and processes that are currently in use by the system.

How do I get the list of connected devices in Linux? ›

List All Devices on Local Network with Linux

Get Tool. Get the tool: sudo apt install arp-scan.
Determine Network Interface. How are you connected to the network? Run: ifconfig. ...
Scan for Devices. sudo arp-scan --interface=wlp0s20f3 --localnet. Read results, including IPs, MAC addresses and vendor brand names.

Sep 11, 2023

How do I see all active connections? ›

How to use the netstat command to view network connections

Click the 'Start' button.
Enter 'cmd' into the search bar to open the command prompt.
Wait for command prompt (black window) to appear. ...
Enter 'netstat -a' to view current connections. ...
Enter 'netstat -b' to see the programs using connections.

More items...

May 6, 2019

View Details ›

How do I see all the keys in ssh-agent? ›

Running ssh-add -l will display all keys currently known to your agent. If the list is empty, you have an ssh-agent running, but no keys currently unlocked.

Where are my SSH keys stored Linux? ›

On Linux systems, the default location for SSH keys is in the user's personal directory in the file ~/. ssh/known_hosts. On Windows systems, the default file location is in the user's personal directory in the file C:\Users\username\. ssh\known_hosts.

Learn More ›

How to list all user commands in Linux? ›

How Do I List Users in Linux? You can list user accounts on Linux using the commands cat /etc/passwd or getent passwd. To see just the usernames, use awk -F: '{ print $1 }' /etc/passwd or cut -d: -f1 /etc/passwd. To find currently logged-in users, use the users command.

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How do I list all shells in Linux? ›

Another method to list available shells is by examining the /etc/shells file using the grep command. In Linux, the grep command is a powerful command-line tool for text searching and filtering. The command output displays a list of available shells on the system, excluding any lines that start with the # symbol.

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