🐧Linux

id_rsa (private key)

What is it?

The id_rsa is a private key used in RSA cryptography systems. It serves for secure authentication in connections, such as in SSH, providing secure access to remote systems and ensuring communication integrity.

How to use via SSH:

The first step is to grant permissions to the file id_rsa:

chmod 600 id_rsa

Afterwards, we can use it, for example, in SSH with the following command:

ssh -i id_rsa user@IP

And we would access the target machine without the need for a password.

Example of a id_rsa (private key) content:

-----BEGIN RSA PRIVATE KEY-----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-----END RSA PRIVATE KEY-----

Where is it?

If the user is named John, it's most likely that the id_rsa (private key) is located in the directory /home/john/.ssh/id_rsa.

In the case of root, it's most likely located in the directory /root/.ssh/id_rsa.