The Server’s Host Key Was Not Found in the Cache: Everything Dev Needs to Know

Dear Dev, are you tired of encountering the server’s host key not found in the cache error message? This error message can be frustrating and confusing, especially when you’re trying to access a server remotely. In this journal article, we’ll explain everything you need to know about this error message and how to fix it.

What is the server’s host key not found in the cache error message?

The server’s host key not found in the cache error message occurs when you’re trying to access a server remotely, and your computer can’t find the host key in its cache. When you connect to a server for the first time, your computer saves the server’s host key in its cache.

However, if the server’s host key has changed since your last connection, your computer won’t have the updated host key in its cache, and you’ll see the server’s host key not found in the cache error message.

Why does the server’s host key change?

The server’s host key changes when the server’s administrator re-installs the operating system or changes the SSH server. These changes can result in the server’s host key changing, and your computer can no longer authenticate the server.

Now that we understand what causes this error message let’s look at how to fix it.

Fixing the server’s host key not found in the cache error message

Method 1: Remove the old host key from your computer’s cache

The first method to fix this error message is to remove the old host key from your computer’s cache. This will force your computer to get the new host key from the server.

Here’s how to remove the old host key from your computer’s cache:

1. Open your computer’s terminal or command prompt.
2. Type the following command: ssh-keygen -R [server’s IP address]
3. Replace [server’s IP address] with the IP address of the server you’re trying to connect to.
4. Press Enter.

After running this command, your computer’s cache should be updated with the new host key.

Method 2: Update your computer’s known_hosts file

The second method to fix this error message is to update your computer’s known_hosts file. This file contains a list of all the server’s host keys that your computer has saved.

Here’s how to update your computer’s known_hosts file:

1. Open your computer’s terminal or command prompt.
2. Type the following command: ssh-keyscan [server’s IP address] >> ~/.ssh/known_hosts
3. Replace [server’s IP address] with the IP address of the server you’re trying to connect to.
4. Press Enter.

After running this command, your computer’s known_hosts file should be updated with the new host key.

FAQs

1. Can I prevent the server’s host key from changing?

No, you can’t prevent the server’s host key from changing. The server’s host key can change when the server’s administrator re-installs the operating system or changes the SSH server.

2. Can I ignore the server’s host key not found in the cache error message?

No, you shouldn’t ignore the server’s host key not found in the cache error message. This error message indicates that your computer can’t authenticate the server, and ignoring it can leave you vulnerable to security threats.

3. Why does my computer save the server’s host key in its cache?

Your computer saves the server’s host key in its cache to enable faster connections to the server in the future. When you connect to the server again, your computer can compare the saved host key with the one presented by the server and authenticate it.

4. Can I delete my computer’s entire known_hosts file to fix this error message?

No, you shouldn’t delete your computer’s entire known_hosts file to fix this error message. This file contains a list of all the server’s host keys that your computer has saved, and deleting it can cause authentication errors for other servers.

Conclusion

In conclusion, the server’s host key not found in the cache error message can be frustrating and confusing, but it’s easy to fix. By removing the old host key from your computer’s cache or updating your computer’s known_hosts file, you can authenticate the server and access it remotely. If you have any more questions or concerns, feel free to consult our FAQs or reach out to us for additional support.