Are you encountering the pesky error message ‘signing failed for RSA ‘PIV AUTH pubkey’ from agent: agent refused operation’ while using your Yubikey for SSH authentication? You’re not alone. Many users face this issue due to a variety of reasons, including forgetting to tap their Yubikey for confirmation, which can lead to significant delays in their operations. However, rebooting your machine every time this happens is no longer necessary. In this article, we will walk you through a step-by-step guide to quickly resolve these Yubikey SSH signing errors, so you can get back to secure access with minimal disruption. Let’s dive in and understand the underlying issues before moving onto efficient fixes.

Key Takeaways

• Yubikey SSH signing errors can occur if users forget to tap their device for confirmation.
• To fix the issue, users can kill and restart SSH agent processes without rebooting the machine.
• The root cause of Yubikey failures is unclear but may involve the ssh-pkcs11-helper getting stuck.

Understanding the Yubikey SSH Signing Issue

### Understanding the Yubikey SSH Signing Issue
Using a Yubikey for SSH authentication can significantly enhance your security, but many users encounter a frustrating issue: the cryptic error message ‘signing failed for RSA ‘PIV AUTH pubkey’ from agent: agent refused operation.’ This problem typically arises when users forget to tap their Yubikey for confirmation, which causes delays in execution and can halt your workflow. Fortunately, resolving this issue has become much simpler and does not require rebooting your machine.

The primary workaround involves terminating active SSH agent processes followed by a restart of the SSH agent. To implement this solution, first, you should kill all running SSH agent processes. You can do this by executing the command `pkill ssh` in your terminal. Next, restart the SSH agent by using the command `eval `ssh-agent -s“. After the SSH agent is back up, you will need to load your Yubikey key into the agent by running `ssh-add -s /usr/lib/x86_64-linux-gnu/opensc-pkcs1

1.so`. For added convenience, consider adding an alias in your `~/.bashrc` file to streamline this process in the future.

While the exact reasons behind Yubikey failures remain somewhat mysterious, it is suspected that the issue may stem from the `ssh-pkcs11-helper` becoming unresponsive during interactions with the Yubikey hardware. By understanding and following these steps, you can minimize interruptions and enjoy the enhanced security provided by your Yubikey in your SSH operations.

Step-by-Step Fixes for Yubikey Errors

### Additional Troubleshooting Tips for Yubikey SSH Authentication

If the initial steps do not resolve your Yubikey issue, there are additional troubleshooting measures you can take. First, ensure that your Yubikey firmware is updated to the latest version, as outdated firmware can lead to compatibility issues with SSH operations. You may also want to check your system for any conflicting SSH configurations in your `~/.ssh/config` file, as these might interfere with the functioning of your Yubikey. Another useful approach is to verify that your Yubikey is properly recognized by the system by running the command `ykman list`, which displays the Yubikey’s details. This helps ensure the device is connected and functioning as expected. If you continue to face issues, reexamine the permissions on the `/usr/lib/x86_64-linux-gnu/opensc-pkcs11.so` file to ensure that your user has the necessary access rights. These additional steps should help you successfully navigate and resolve any persistent Yubikey errors in your SSH setup.