ssh-add

Examples (TL;DR)

• Add the default ssh keys in "~/.ssh" to the ssh-agent: ssh-add

• Add a specific key to the ssh-agent: ssh-add path/to/private_key

• List fingerprints of currently loaded keys: ssh-add -l

• Delete a key from the ssh-agent: ssh-add -d path/to/private_key

• Delete all currently loaded keys from the ssh-agent: ssh-add -D

tldr.sh

Synopsis

Description

ssh-add adds private key identities to the authentication agent, ssh-agent(1). When run without arguments, it adds the files ~/.ssh/id_rsa, ~/.ssh/id_dsa, ~/.ssh/id_ecdsa, and ~/.ssh/id_ed25519. 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-askpass(1). Successful confirmation is signaled by a zero exit status from ssh-askpass(1), 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.

-q

Be quiet after a successful operation.

-s pkcs11

Add keys provided by the PKCS#11 shared library pkcs11.

-T pubkey ...

Tests whether the private keys that correspond to the specified pubkey files are usable by performing sign and verify operations on each.

-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_config(5).

-v

Verbose mode. Causes ssh-add to print debugging messages about its progress. This is helpful in debugging problems. Multiple -v options increase the verbosity. The maximum is 3.

-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-domain socket used to communicate with the agent.

Files

~/.ssh/id_dsa

Contains the DSA authentication identity of the user.

~/.ssh/id_ecdsa

Contains the ECDSA authentication identity of the user.

~/.ssh/id_ed25519

Contains the Ed25519 authentication identity of the user.

~/.ssh/id_rsa

Contains the 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.

See Also

ssh(1), ssh-agent(1), ssh-askpass(1), ssh-keygen(1), sshd(8)

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.

Referenced By

amaddclient(8), autossh(1), gsissh(1), gsissh_config(5), gsisshd(8), gsissh-keygen(1), keychain(1), ksshaskpass(1), kwalletaskpass(1), pam_ssh(8), scp(1), sftp(1), ssh(1), ssh-agent(1), ssh_config(5), ssh-copy-id(1), sshd(8), ssh-keygen(1), ssh-pkcs11-helper(8), x11-ssh-askpass.1x(1).