You can also add an optional comment field to the public key with the -C switch, to more easily identify it in places such as ~/.ssh/known_hosts, ~/.ssh/authorized_keys and ssh-add -L output.
#Ssh copy id windows command prompt password#
Note: You can use the -a switch to specify the number of KDF rounds on the password encryption. The randomart image was introduced in OpenSSH 5.1 as an easier means of visually identifying the key fingerprint. SHA256:gGJtSsV8BM+7w018d39Ji57F8iO6c0N2GZq3/RY2NhI key's randomart image is: Your public key has been saved in /home//.ssh/id_rsa.pub. Your identification has been saved in /home//.ssh/id_rsa. The passphrase is not transmitted over the network.Īn SSH key pair can be generated by running the ssh-keygen command, defaulting to 3072-bit RSA (and SHA256) which the ssh-keygen(1) man page says is " generally considered sufficient" and should be compatible with virtually all clients and servers:Įnter file in which to save the key (/home//.ssh/id_rsa):Įnter passphrase (empty for no passphrase): While this might superficially appear as though you are providing a login password to the SSH server, the passphrase is only used to decrypt the private key on the local system. When the encrypted private key is required, a passphrase must first be entered in order to decrypt it. As long as you hold the private key, which is typically stored in the ~/.ssh/ directory, your SSH client should be able to reply with the appropriate response to the server.Ī private key is a guarded secret and as such it is advisable to store it on disk in an encrypted form. This challenge-response phase happens behind the scenes and is invisible to the user. Only you, the holder of the private key, will be able to correctly understand the challenge and produce the proper response. While the public key can be used to encrypt the message, it cannot be used to decrypt that very same message. What makes this coded message particularly secure is that it can only be understood by the private key holder. This challenge is an encrypted message and it must be met with the appropriate response before the server will grant you access. If an SSH server has your public key on file and sees you requesting a connection, it uses your public key to construct and send you a challenge. By contrast, the public key can be shared freely with any SSH server to which you wish to connect. The private key is known only to you and it should be safely guarded. SSH keys are always generated in pairs with one known as the private key and the other as the public key. 4.5.1 Using a different password to unlock the SSH key.
3 Copying the public key to the remote server.2.2.3 Storing SSH keys on hardware tokens.2.2.1 Changing the private key's passphrase without changing the key.2.2 Choosing the key location and passphrase.2.1 Choosing the authentication key type.This article assumes you already have a basic understanding of the Secure Shell protocol and have installed the openssh package. A general understanding of how SSH keys work will help you decide how and when to use them to meet your needs.
Key-based authentication is not without its drawbacks and may not be appropriate for all environments, but in many circumstances it can offer some strong advantages. When used with a program known as an SSH agent, SSH keys can allow you to connect to a server, or multiple servers, without having to remember or enter your password for each system. The major advantage of key-based authentication is that, in contrast to password authentication, it is not prone to brute-force attacks, and you do not expose valid credentials if the server has been compromised (see RFC 4251 9.4.4).įurthermore, SSH key authentication can be more convenient than the more traditional password authentication. SSH keys can serve as a means of identifying yourself to an SSH server using public-key cryptography and challenge-response authentication. Reason: The intro and Background section ignore the server perspective.