📖 What is Secure Shell (SSH)?
Secure Shell (SSH) is a cryptographic network protocol used for operating network services securely over an unsecured network. It is most commonly used for remote command-line login and remote command execution on Linux and Unix servers.
"SSH uses port 22. Contrast this with Telnet, which is considered insecure because it sends all data, including passwords, in plaintext."
📚 Certification: CompTIA A+ Certification Exam Core 2 (220-1102)
🔑 What are the Key Concepts of Secure Shell (SSH)?
- ▸ SSH operates on TCP port 22 by default, providing a secure channel for administrative access to network devices and servers across untrusted networks.
- ▸ Unlike Telnet, SSH encrypts all traffic, including usernames and passwords, preventing attackers from capturing sensitive credentials using packet sniffing tools like Wireshark.
- ▸ Authentication can be handled via traditional passwords or SSH key pairs, where a public key is stored on the server and a private key remains with the user.
- ▸ It is the primary tool for remote command-line interface (CLI) management of Linux/Unix systems and many modern network switches and routers.
- ▸ SSH provides the underlying secure transport for other protocols, such as SFTP (Secure File Transfer Protocol), allowing for encrypted file movement over the same port.
🎯 How does Secure Shell (SSH) appear on the 220-1102 Exam?
You may be asked to identify the most secure method for a technician to remotely manage a Linux server from a different subnet without exposing credentials in plaintext.
A scenario might describe a firewall configuration where a technician must open a specific port to allow remote administration; you must identify TCP port 22 as the correct choice.
Expect questions comparing SSH and Telnet, where you must select SSH as the solution to mitigate the risk of man-in-the-middle attacks during remote sessions.
❓ Frequently Asked Questions
Why is Telnet still mentioned in the exam if SSH is the standard?
Telnet is included to emphasize the danger of plaintext communication. It serves as a critical contrast to show why encryption is mandatory for modern remote administration.
What is the difference between password authentication and key-based authentication?
Password authentication relies on a shared secret, while key-based authentication uses a cryptographic pair. Key-based is more secure as it eliminates the risk of brute-force password attacks.