SSH (Secure Shell) is a protocol for secure access and management of systems through an unsecure network. It uses 22 ports by default. Its main functions include remote login, secure file transfer, application tunneling and remote task automation. SSH differs from Telnet and FTP in that its communication is encrypted throughout and supports multiple authentication methods, such as password and public key authentication, ensuring data privacy and tamper-proof. 1. Remote login to the server 2. Securely transfer files using SCP or SFTP 3. Forward other applications via encrypted channels 4. Automate tasks on remote machines via scripts. While ports can be changed to reduce automatic attack attempts, the core advantage lies in encryption and security mechanisms.

SSH, or Secure Shell, is a protocol used to securely access and management systems over an unsecureated network. It's widely used by system administrators and developers to log into remote servers, transfer files, and execute commands safely. The main thing that sets SSH apart from other protocols like Telnet or FTP is encryption — everything you do over an SSH connection is encrypted, making it much harder for anyone to intercept your data.

What Exactly Does SSH Do?

SSH provides a secure way to connect to another computer over a network. You might use it to log into a server, run commands remotely, or even forward graphic applications over the network. Here are some of its most common uses:

• Remote login to a server
• Secure file transfers (using tools like SCP or SFTP)
• Tunneling other applications through an encrypted channel
• Automating tasks on remote machines via scripts

It's especially popular in environments where security is important, like web hosting, cloud computing, and DevOps workflows.

Which Port Does SSH Use by Default?

By default, SSH runs on port 22 . This is standardized across most Unix-like operating systems and network devices. So when you connect to a server using SSH without specifying a port — like with ssh user@hostname — it automatically tries to reach the SSH service on port 22.

That said, you can change the port if needed, usually for security reasons like avoiding automated attacks. For example, many administrators configure SSH to listen on a different port such as 2222 or 2222. If you're connecting to a server that uses a non-standard port, you just specify it with the -p flag:

 ssh -p 2222 user@hostname

Just remember: changing the port doesn't make your server completely secure, but it can reduce noise from bots scanning the default port.

How Is SSH Different From Other Protocols?

Compared to older protocols like Telnet or FTP, SSH brings a big advantage: encryption . With Telnet, everything you type — including passwords — is sent in plain text, which means anyone monitoring the network could see it. SSH avoids that by encrypting all communication.

Also, unlike basic FTP, SSH supports secure file transfers through SFTP or SCP, which are built right into the SSH protocol. That makes it more versatile and secure than separate file transfer tools that don't offer encryption by default.

Another key difference is authentication. SSH supports multiple methods, including password-based login and public-key authentication, which is both more secure and convenient once set up properly.

So yeah, SSH is basically the go-to tool for secure remote access, and it works out of the box on port 22. You can tweak things like the port number or authentication method depending on your needs, but the core idea remains the same: keep your connections private and tamper-proof.

The above is the detailed content of What is SSH (Secure Shell) and what port does it use?. For more information, please follow other related articles on the PHP Chinese website!