Telnet vs SSH
Both protocols used for remote access, but SSH is significantly more secure because it encrypts data transmission, while Telnet transmits data in plain text, making it vulnerable to eavesdropping
What is Telnet?
- Basic Protocol: Telnet is a protocol used for remote access to servers and devices.
- Plain Text Transmission: Data is sent in plain text, making it susceptible to interception and eavesdropping.
- No Encryption: Lacks encryption, which exposes sensitive information like passwords to anyone who can capture the data packets.
- Simple Authentication: Primarily uses username and password for authentication without any secure methods.
- Command-Line Interface: Provides a command-line interface for users to interact with remote systems.
- Port Usage: Operates typically over port 23, which can be easily blocked by firewalls due to security concerns.
- Limited Security Features: Does not offer built-in mechanisms for session encryption or integrity protection.
- Legacy Support: Often used in legacy systems and applications where security is not a primary concern.
- File Transfers: Does not natively support secure file transfers; relies on additional protocols for that purpose.
- Interactivity: Allows for interactive sessions, but the lack of security limits its use in modern applications.
Telnet Configuration on Cisco Router
Telnet Configuration on Cisco Packet Tracer.
What is SSH? SSH Configuration on Cisco Router.
- Secure Protocol: SSH (Secure Shell) provides a secure channel over an unsecured network.
- Encryption: Encrypts all data transmitted between the client and server to protect against eavesdropping.
- Authentication: Supports various authentication methods, including password-based and key-based authentication.
- Port Forwarding: Allows secure tunneling of other protocols and services through its connection.
- Integrity: Ensures data integrity using cryptographic checksums to prevent tampering.
- Session Management: Supports multiple concurrent sessions and can reconnect to sessions if the connection drops.
- Cross-Platform: Available on various operating systems, including Linux, macOS, and Windows.
- Public Key Infrastructure (PKI): Uses public/private key pairs for secure authentication.
- Command Execution: Enables remote command execution and file transfers securely using SCP or SFTP.
- Firewall Friendly: Operates over a single port (default is port 22), making it easier to manage through firewalls.
SSH used hostname and ip domain name for encryption keys.
- hostname
- ip domain-name
- cryptokey generate RSA
512 - ssh version 1
768+ - ssh version 2
line vty 0 9
login local
transport input ssh
username gaurav password gaurav
username abhi password abhi
enable password cisco
Here’s a comparison table between SSH and Telnet to help you prepare for your interview:
Feature | SSH | Telnet |
Security | Encrypts data transmission | Transmits data in plain text |
Authentication | Supports key-based and password-based | Primarily uses username and password |
Data Integrity | Ensures data integrity using checksums | No integrity checks |
Port | Default is port 22 | Default is port 23 |
Protocol Support | Supports secure file transfer (SCP/SFTP) | Relies on other protocols for file transfer |
Session Management | Allows multiple concurrent sessions | Limited to a single session |
Firewall Compatibility | Easier to manage due to single port | May be blocked due to security concerns |
Interactivity | Provides interactive command-line access | Provides interactive command-line access |
Use Cases | Recommended for secure remote administration | Suitable for legacy systems without security concerns |
Cross-Platform | Available on various operating systems | Available but less common on modern systems |
