SSH Host Key Checker

Check SSH server host key type and fingerprint

About SSH Host Key Verification

When you connect to an SSH server for the first time, the server presents its host key — a cryptographic identity that helps you verify you're connecting to the legitimate server and not an imposter. SSH host keys come in several types (RSA, ECDSA, Ed25519), each with different security properties. Our SSH Host Key Checker connects to any SSH server, retrieves its host key, and displays the key type alongside SHA-256 and MD5 fingerprints for easy verification against known values.

How to Use

Enter the SSH server hostname or IP address.
Optionally change the port number (default is 22).
Click Check SSH to connect and retrieve the host key.
Compare the displayed SHA-256 and MD5 fingerprints with the server administrator's known values.

Use Cases

Fingerprint Verification: Verify SSH server fingerprints before first connection to prevent man-in-the-middle attacks.
Security Audits: Audit SSH server configurations to ensure they use secure key types (e.g., Ed25519 over 1024-bit RSA).
Server Inventory: Document SSH host key types and fingerprints across your server fleet for asset management.
Incident Response: Investigate SSH host key changes that may indicate a server compromise or key rotation.

Frequently Asked Questions

Verifying SSH host keys protects against man-in-the-middle attacks. When you connect to a server, checking the fingerprint against a trusted source (such as your server console or documentation) ensures you are communicating with the legitimate server.

Ed25519 is widely considered the most secure and efficient SSH key type due to its strong elliptic curve cryptography and small key size. ECDSA with a P-256 curve is also strong. RSA keys with 3072+ bit lengths remain secure but are less efficient.

A mismatched host key can indicate a man-in-the-middle attack, a server compromise, or a legitimate key rotation. If you did not expect a key change, contact your server administrator immediately and do not connect.

Tips & Best Practices

•Use Ed25519 or ECDSA keys for better security and performance
•Protect private keys with strong passphrases
•Regularly rotate host keys for servers with high security requirements
•Verify host key fingerprints before connecting to unfamiliar servers

Technical Details

Key Types: RSA, DSA, ECDSA (P-256, P-384, P-521), Ed25519
Fingerprints: MD5, SHA-1, SHA-256 hash algorithms
Format: OpenSSH key format analysis
Security: Key size, algorithm strength, and best practices assessment