www.LinuxHowtos.org

SSH-ADD

Section: User Commands (1)
Index Return to Main Contents

BSD mandoc

NAME

ssh-add - adds private key identities to the authentication agent

SYNOPSIS

ssh-add [-cDdkLlXx [-E fingerprint_hash ] ] [-t life ] [file ... ]
ssh-add -s pkcs11
ssh-add -e pkcs11

DESCRIPTION

ssh-add adds private key identities to the authentication agent, ssh-agent1. When run without arguments, it adds the files ~/.ssh/id_rsa ~/.ssh/id_dsa ~/.ssh/id_ecdsa ~/.ssh/id_ed25519 and ~/.ssh/identity After loading a private key, ssh-add will try to load corresponding certificate information from the filename obtained by appending -cert.pub to the name of the private key file. Alternative file names can be given on the command line.

If any file requires a passphrase, ssh-add asks for the passphrase from the user. The passphrase is read from the user's tty. ssh-add retries the last passphrase if multiple identity files are given.

The authentication agent must be running and the SSH_AUTH_SOCK environment variable must contain the name of its socket for ssh-add to work.

The options are as follows:

-c: Indicates that added identities should be subject to confirmation before being used for authentication. Confirmation is performed by ssh-askpass1. Successful confirmation is signaled by a zero exit status from ssh-askpass1, rather than text entered into the requester.
-D: Deletes all identities from the agent.
-d: Instead of adding identities, removes identities from the agent. If ssh-add has been run without arguments, the keys for the default identities and their corresponding certificates will be removed. Otherwise, the argument list will be interpreted as a list of paths to public key files to specify keys and certificates to be removed from the agent. If no public key is found at a given path, ssh-add will append .pub and retry.
-E fingerprint_hash: Specifies the hash algorithm used when displaying key fingerprints. Valid options are: ``md5'' and ``sha256'' The default is ``sha256''
-e pkcs11: Remove keys provided by the PKCS#11 shared library pkcs11
-k: When loading keys into or deleting keys from the agent, process plain private keys only and skip certificates.
-L: Lists public key parameters of all identities currently represented by the agent.
-l: Lists fingerprints of all identities currently represented by the agent.
-s pkcs11: Add keys provided by the PKCS#11 shared library pkcs11
-t life: Set a maximum lifetime when adding identities to an agent. The lifetime may be specified in seconds or in a time format specified in sshd_config5.
-X: Unlock the agent.
-x: Lock the agent with a password.

ENVIRONMENT

DISPLAY and SSH_ASKPASS: If ssh-add needs a passphrase, it will read the passphrase from the current terminal if it was run from a terminal. If ssh-add does not have a terminal associated with it but DISPLAY and SSH_ASKPASS are set, it will execute the program specified by SSH_ASKPASS (by default ``ssh-askpass'' and open an X11 window to read the passphrase. This is particularly useful when calling ssh-add from a .xsession or related script. (Note that on some machines it may be necessary to redirect the input from /dev/null to make this work.)
SSH_AUTH_SOCK: Identifies the path of a UNIX socket used to communicate with the agent.

FILES

~/.ssh/identity: Contains the protocol version 1 RSA authentication identity of the user.
~/.ssh/id_dsa: Contains the protocol version 2 DSA authentication identity of the user.
~/.ssh/id_ecdsa: Contains the protocol version 2 ECDSA authentication identity of the user.
~/.ssh/id_ed25519: Contains the protocol version 2 Ed25519 authentication identity of the user.
~/.ssh/id_rsa: Contains the protocol version 2 RSA authentication identity of the user.

Identity files should not be readable by anyone but the user. Note that ssh-add ignores identity files if they are accessible by others.

EXIT STATUS

Exit status is 0 on success, 1 if the specified command fails, and 2 if ssh-add is unable to contact the authentication agent.

AUTHORS

OpenSSH is a derivative of the original and free ssh 1.2.12 release by Tatu Ylonen. Aaron Campbell, Bob Beck, Markus Friedl, Niels Provos, Theo de Raadt and Dug Song removed many bugs, re-added newer features and created OpenSSH. Markus Friedl contributed the support for SSH protocol versions 1.5 and 2.0.