Granting Someone Else Access to Your Server If your file contains more than one public key, then the owner of each key listed can log in as that user. A user’s authorized_keys file can store more than one public key, and each public key is listed on its own line. This file is stored inside a directory named. To set up SSH key authentication for one of your server’s users, add your public key to a new line inside the user’s authorized_keys file. If you would like to log in to more than one user on the server using your key pair, you must add your public key to each of those users. More specifically, you must upload your public key to the home directory of the user you would like to log in as. In order for your Linux server to recognize and accept your key pair, you must upload your public key to your server. To match these keys and validate, you use an algorithm like Diffie-Hellman. But when the receiver decrypts this message, they can safely and securely validate that the communication is in fact from you. When you sign a message, you allow others to decrypt the message as well. A signed message is verified by using this public key to decrypt the message. Verification of communication: Your server has a public key from the sender stored. Signed communication: Any message that goes out is signed using your private keys. To facilitate this encryption and decryption, an authentication algorithm is used. To enable encrypted communication between machines, you would retain your private key on your workstation and share your public key with the remote machines you’d like to access. When you use your public key to encrypt something, only your private key can decrypt it. But how? The best way to understand them is to understand that the following components in this authentication system are mathematically related to each other: For instance, services like GitHub and Gitlab allow you to place your SSH public key on their servers to streamline the process of pushing code changes to remote repositories.Ī public key and a private key play an important role in enabling secure access. When a site or service asks for your SSH key, they are referring to your SSH public key ( id_rsa.pub). If someone else adds your public key to their server, you will be able to log in to that server. You can freely share your public key with others. The public key is placed on the server you intend to log in to. This guide explains how the SSH key login scheme works, how to generate an SSH key, and how to use those keys with a Linode Linux server.ĭo not share your private key with others.Ī public key, usually named id_rsa.pub. For example, you can set up periodic updates for your servers with a configuration management tool like Ansible, and you can run those updates without having to be physically present. If a server that uses SSH keys is compromised by a hacker, no authorization credentials are at risk of being exposed.īecause a password isn’t required at login, you can log into servers from within scripts or automation tools that you need to run unattended. Key-based login is not a major target for brute-force hacking attacks. Using key-based authentication offers a range of benefits, including: Password authentication is the default method most SSH clients use to authenticate with remote servers, but it suffers from potential security vulnerabilities like brute-force login attempts. Public key authentication with SSH (Secure Shell) is a method in which you generate and store on your computer a pair of cryptographic keys and then configure your server to recognize and accept your keys.
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