||FreeBSD General Commands Manual
ssh-add - adds private key identities to the OpenSSH authentication agent
ssh-add [-cDdKkLlqvXx] [-E fingerprint_hash]
[-H hostkey_file] [-h destination_constraint]
[-S provider] [-t life] [file ...]
ssh-add -s pkcs11
ssh-add -e pkcs11
ssh-add -T pubkey...
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, ~/.ssh/id_ed25519_sk, and
~/.ssh/id_dsa. 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
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:
- 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
- Deletes all identities from the agent.
- 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
- -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, /usr/local/etc/ssh/ssh_known_hosts, and
- -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
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 . 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)
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).
- Load resident keys from a FIDO authenticator.
- When loading keys into or deleting keys from the agent, process plain
private keys only and skip certificates.
- Lists public key parameters of all identities currently represented by the
- Lists fingerprints of all identities currently represented by the
- 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.
- -T pubkey...
- Tests whether the private keys that correspond to the specified
pubkey files are usable by performing sign and verify operations on
- -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
- 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.
- Unlock the agent.
- Lock the agent with a password.
- 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.
- Identifies the path of a UNIX-domain socket used to communicate with the
- 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.
- Contains the DSA, ECDSA, authenticator-hosted ECDSA, Ed25519,
authenticator-hosted Ed25519 or RSA authentication identity of the
Identity files should not be readable by anyone but the user. Note
that ssh-add ignores identity files if they are accessible by
Exit status is 0 on success, 1 if the specified command fails, and 2 if
ssh-add is unable to contact the authentication agent.
ssh(1), ssh-agent(1), ssh-askpass(1), ssh-keygen(1),
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.
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