ssh-add(1) General Commands Manual ssh-add(1)

NAME

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

SYNOPSIS

 ssh-add [-CcDdKkLlqvXx] [-E fingerprint_hash] [-H hostkey_file]
 [-h destination_constraint] [-S provider] [-t life] [file ...]
 ssh-add -s pkcs11 [-Cv] [certificate ...]
 ssh-add -e pkcs11
 ssh-add -T pubkey ...

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_ecdsa, ~/.ssh/id_ecdsa_sk, ~/.ssh/id_ed25519 and
 ~/.ssh/id_ed25519_sk. 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 When loading keys into or deleting keys from the agent, process
 certificates only and skip plain keys.
 -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. If
 the argument list consists of "-" then ssh-add will read public
 keys to be removed from standard input.
 -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.
 -H hostkey_file
 Specifies a known hosts file to look up hostkeys when using
 destination-constrained keys via the -h flag. This option may be
 specified multiple times to allow multiple files to be searched.
 If no files are specified, ssh-add will use the default
 ssh_config(5)  known hosts files: ~/.ssh/known_hosts,
 ~/.ssh/known_hosts2, /opt/local/etc/ssh/ssh_known_hosts, and
 /opt/local/etc/ssh/ssh_known_hosts2.
 -h destination_constraint
 When adding keys, constrain them to be usable only through
 specific hosts or to specific destinations.
 Destination constraints of the form `[user@]dest-hostname' permit
 use of the key only from the origin host (the one running
 ssh-agent(1) ) to the listed destination host, with optional user
 name.
 Constraints of the form `src-hostname>[user@]dst-hostname' allow
 a key available on a forwarded ssh-agent(1)  to be used through a
 particular host (as specified by `src-hostname') to authenticate
 to a further host, specified by `dst-hostname'.
 Multiple destination constraints may be added when loading keys.
 When attempting authentication with a key that has destination
 constraints, the whole connection path, including ssh-agent(1) 
 forwarding, is tested against those constraints and each hop must
 be permitted for the attempt to succeed. For example, if key is
 forwarded to a remote host, `host-b', and is attempting
 authentication to another host, `host-c', then the operation will
 be successful only if `host-b' was permitted from the origin host
 and the subsequent `host-b>host-c' hop is also permitted by
 destination constraints.
 Hosts are identified by their host keys, and are looked up from
 known hosts files by ssh-add. Wildcards patterns may be used for
 hostnames and certificate host keys are supported. By default,
 keys added by ssh-add are not destination constrained.
 Destination constraints were added in OpenSSH release 8.9.
 Support in both the remote SSH client and server is required when
 using destination-constrained keys over a forwarded ssh-agent(1) 
 channel.
 It is also important to note that destination constraints can
 only be enforced by ssh-agent(1)  when a key is used, or when it
 is forwarded by a cooperating ssh(1) . Specifically, it does not
 prevent an attacker with access to a remote SSH_AUTH_SOCK from
 forwarding it again and using it on a different host (but only to
 a permitted destination).
 -K Load resident keys from a FIDO authenticator.
 -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 provider
 Specifies a path to a library that will be used when adding FIDO
 authenticator-hosted keys, overriding the default of using the
 internal USB HID support.
 -s pkcs11
 Add keys provided by the PKCS#11 shared library pkcs11.
 Certificate files may optionally be listed as command-line
 arguments. If these are present, then they will be loaded into
 the agent using any corresponding private keys loaded from the
 PKCS#11 token.
 -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, SSH_ASKPASS and SSH_ASKPASS_REQUIRE
 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.
 SSH_ASKPASS_REQUIRE allows further control over the use of an
 askpass program. If this variable is set to "never" then ssh-add
 will never attempt to use one. If it is set to "prefer", then
 ssh-add will prefer to use the askpass program instead of the TTY
 when requesting passwords. Finally, if the variable is set to
 "force", then the askpass program will be used for all passphrase
 input regardless of whether DISPLAY is set.
 SSH_AUTH_SOCK
 Identifies the path of a UNIX-domain socket used to communicate
 with the agent.
 SSH_SK_PROVIDER
 Specifies a path to a library that will be used when loading any
 FIDO authenticator-hosted keys, overriding the default of using
 the built-in USB HID support.

FILES

 ~/.ssh/id_ecdsa
 ~/.ssh/id_ecdsa_sk
 ~/.ssh/id_ed25519
 ~/.ssh/id_ed25519_sk
 ~/.ssh/id_rsa
 Contains the ECDSA, authenticator-hosted ECDSA, Ed25519,
 authenticator-hosted Ed25519 or 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.
macOS 14.6 June 17, 2024 macOS 14.6