How SSH Works: A Step-by-Step Guide with Examples
Imagine you have a computer at home and another one at your office. Now, you want to access your office computer from home to get some work done. How do you do that safely? This is where SSH comes in.
What is SSH?
SSH is like a special kind of secure tunnel for sending information between two computers over the internet. It’s kind of like sending a letter in a locked box instead of a regular envelope. The person at the other end has the key to open the box (or in the case of SSH, the correct password or key). This way, no one else who might intercept the box (or your data) can open it and see what’s inside.
Why SSH is Important?
-
Security: The most important aspect of SSH is that it keeps your data safe. When you’re sending information, like your login details or files, over the internet, it’s possible for others to intercept and see this data. SSH encrypts your data, meaning it scrambles the information into a code that is very hard to crack. Only the intended recipient, who has the right key, can unscramble this code and see the actual information.
-
Privacy: Because the data is encrypted, your information stays private. It’s like having a private conversation in a public space, but in a language only you and your friend understand.
-
Authenticity: SSH makes sure that you’re actually connecting to the computer you think you’re connecting to. This prevents someone from pretending to be your office computer to steal information.
-
Versatility: SSH can be used for more than just logging into another computer. It can also safely transfer files, manage network resources, and do remote administration work, all while keeping the data secure.
How SSH Differs from Other Protocols
| Feature | SSH (Secure Shell) | Telnet |
|---|---|---|
| Security | Uses strong encryption. Similar to sending data in a locked, unbreakable box. | No encryption. Like sending data in a clear envelope, visible to anyone. |
| Authentication | Verifies the remote computer’s identity securely. Comparable to a secret handshake only known to involved parties. | Does perform identity checks, but without encryption, making it insecure. |
| Privacy | Ensures high privacy due to encryption. Like having a conversation in a secure room. | Offers little to no privacy; transmitted data can be easily intercepted and read. |
| Functionality | Versatile: secure command execution, file transfer, port forwarding. | Basic: primarily used for remote command execution, lacks additional secure features. |
| Risk Factor | Considered very secure, the standard for secure remote communication. | High risk due to lack of encryption; not recommended for secure communication. |
| Use Cases | Widely used for secure remote administration, file transfers, and command execution. | Outdated for secure purposes; only used in legacy systems or non-secure environments. |
What Port Does SSH Use?
SSH (Secure Shell) typically uses port 22. This is the default port for SSH connections and is used for securely accessing remote machines and transferring files. When you connect to a server via SSH, unless specified otherwise, your computer will attempt to connect to port 22 on the remote server.