How to Fix Warning: Remote Host Identification Has Changed?

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What Does “Warning: Remote Host Identification Has Changed!” Mean?

The Warning: REMOTE HOST IDENTIFICATION HAS CHANGED!” typically appears when connecting via SSH to a server whose host key has changed since the last connection. This can be a security warning, possibly indicating a man-in-the-middle (MITM) attack, or it might just be because the server was reinstalled or its keys regenerated.

This SSH warning appears when the remote server’s fingerprint changes, indicating potential security risks. Common causes include:

The server was reinstalled or its SSH key changed.
You connected to a different server with the same IP or hostname.
A man-in-the-middle attack could be altering the connection.

⚠️ Example Warning Message:

python-repl

@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!
...
Offending ECDSA key in ~/.ssh/known_hosts:12
...

Steps to Fix It (If You Trust the New Host):

View the offending key line number

The error will usually mention a line in your ~/.ssh/known_hosts file.

Remove the old key

You can remove the old key using the ssh-keygen command:

bash

ssh-keygen -R "hostname or IP"

Example:

bash

ssh-keygen -R example.com

This removes the outdated key for that host from ~/.ssh/known_hosts.

Reconnect to the server

Try SSH again:

bash

ssh user@example.com

It will prompt you to confirm the new key, and once accepted, it’ll be stored in your known_hosts file.

How to Prevent This Warning in the Future?

Use Static IPs to avoid accidental key mismatches.
Check for unauthorized changes before accepting a new key.
Maintain a backup of known SSH keys for trusted hosts.

🔐 Security Tip:

Only proceed if you are sure the server change is legitimate (e.g., someone reinstalled the server or updated SSH keys). If you’re not sure, confirm with the server admin before trusting the new key.

About Author

Jayanti Katariya is the CEO of Moon Technolabs, a fast-growing IT solutions provider, with 18+ years of experience in the industry. Passionate about developing creative apps from a young age, he pursued an engineering degree to further this interest. Under his leadership, Moon Technolabs has helped numerous brands establish their online presence and he has also launched an invoicing software that assists businesses to streamline their financial operations.