man > ssh-add(1)

TLDR: ssh-add (tldr-pages)

Manage loaded SSH keys in the `ssh-agent`.

  • 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
  • Add a key to the `ssh-agent` and the keychain
    ssh-add -K {{path/to/private_key}}
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 [-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 con‐
       tain 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 confir‐
               mation  is  signaled  by a zero exit status from ssh-askpass(1), rather than text en‐
               tered 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 “-” 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,
               /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  spe‐
               cific 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 au‐
               thentication  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  con‐
               straints.

               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 re‐
               mote 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 op‐
               tionally 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 us‐
               able by performing sign and verify operations on each.

       -t life
               Set a maximum lifetime when adding identities to an agent.  The lifetime may be spec‐
               ified 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_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.

Debian                                    December 18, 2023                               SSH-ADD(1)
ssh-add(1)
NAME SYNOPSIS DESCRIPTION
-c Indicates that added identities should be subject to confirmation before being used -C When loading keys into or deleting keys from the agent, process certificates only and -D Deletes all identities from the agent. -d Instead of adding identities, removes identities from the agent. If ssh-add has been -E fingerprint_hash -e pkcs11 -H hostkey_file -h destination_constraint -K Load resident keys from a FIDO authenticator. -k When loading keys into or deleting keys from the agent, process plain private keys -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 -s pkcs11 -T pubkey ... -t life -v Verbose mode. Causes ssh-add to print debugging messages about its progress. This -X Unlock the agent. -x Lock the agent with a password.
ENVIRONMENT FILES EXIT STATUS SEE ALSO AUTHORS

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