openssh/ssh-add.0

SSH-ADD(1)                  General Commands Manual                 SSH-ADD(1)

NAME
     ssh-add M-bM-^@M-^S 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 [-vC] [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,
     ~/.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 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.

     -C      When loading keys into or deleting keys from the agent, process
             certificates only and skip plain keys.

     -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 M-bM-^@M-^\-M-bM-^@M-^] 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: M-bM-^@M-^\md5M-bM-^@M-^] and M-bM-^@M-^\sha256M-bM-^@M-^].  The
             default is M-bM-^@M-^\sha256M-bM-^@M-^].

     -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, /etc/ssh/ssh_known_hosts, and
             /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 M-bM-^@M-^X[user@]dest-hostnameM-bM-^@M-^Y 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 M-bM-^@M-^Xsrc-hostname>[user@]dst-hostnameM-bM-^@M-^Y allow
             a key available on a forwarded ssh-agent(1) to be used through a
             particular host (as specified by M-bM-^@M-^Xsrc-hostnameM-bM-^@M-^Y) to authenticate
             to a further host, specified by M-bM-^@M-^Xdst-hostnameM-bM-^@M-^Y.

             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, M-bM-^@M-^Xhost-bM-bM-^@M-^Y, and is attempting
             authentication to another host, M-bM-^@M-^Xhost-cM-bM-^@M-^Y, then the operation will
             be successful only if M-bM-^@M-^Xhost-bM-bM-^@M-^Y was permitted from the origin host
             and the subsequent M-bM-^@M-^Xhost-b>host-cM-bM-^@M-^Y 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 M-bM-^@M-^\ssh-askpassM-bM-^@M-^]) 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 M-bM-^@M-^\neverM-bM-^@M-^] then ssh-add
             will never attempt to use one.  If it is set to M-bM-^@M-^\preferM-bM-^@M-^], then
             ssh-add will prefer to use the askpass program instead of the TTY
             when requesting passwords.  Finally, if the variable is set to
             M-bM-^@M-^\forceM-bM-^@M-^], 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_dsa
     ~/.ssh/id_ecdsa
     ~/.ssh/id_ecdsa_sk
     ~/.ssh/id_ed25519
     ~/.ssh/id_ed25519_sk
     ~/.ssh/id_rsa
             Contains the DSA, 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.

OpenBSD 7.3                    December 18, 2023                   OpenBSD 7.3