# man > SSH-ADD(1) > **TLDR:** 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}}` *Source: tldr-pages* --- [_SSH-ADD_(1)](https://www.chedong.com/phpMan.php/man/SSH-ADD/1/markdown) General Commands Manual [_SSH-ADD_(1)](https://www.chedong.com/phpMan.php/man/SSH-ADD/1/markdown) ## 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)](https://www.chedong.com/phpMan.php/man/ssh-agent/1/markdown). 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 for authentication. Confirmation is performed by [_ssh-askpass_(1)](https://www.chedong.com/phpMan.php/man/ssh-askpass/1/markdown). Successful confir‐ mation is signaled by a zero exit status from [_ssh-askpass_(1)](https://www.chedong.com/phpMan.php/man/ssh-askpass/1/markdown), rather than text en‐ tered into the requester. ### -C skip plain keys. ### -D ### -d 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 _ Specifies the hash algorithm used when displaying key fingerprints. Valid options are: “md5” and “sha256”. The default is “sha256”. ### -e _ Remove keys provided by the PKCS#11 shared library _pkcs11_. ### -H _ 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)](https://www.chedong.com/phpMan.php/man/sshconfig/5/markdown) known hosts files: _~/.ssh/known_hosts_, _~/.ssh/known_hosts2_, _/etc/ssh/ssh_known_hosts_, and _/etc/ssh/ssh_known_hosts2_. ### -h _ 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)](https://www.chedong.com/phpMan.php/man/ssh-agent/1/markdown)) 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)](https://www.chedong.com/phpMan.php/man/ssh-agent/1/markdown) 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)](https://www.chedong.com/phpMan.php/man/ssh-agent/1/markdown) 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)](https://www.chedong.com/phpMan.php/man/ssh-agent/1/markdown) channel. It is also important to note that destination constraints can only be enforced by [_ssh-agent_(1)](https://www.chedong.com/phpMan.php/man/ssh-agent/1/markdown) when a key is used, or when it is forwarded by a **cooperating _**[ssh_(1)](https://www.chedong.com/phpMan.php/man/ssh/1/markdown). 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 ### -k only and skip certificates. ### -L ### -l ### -q ### -S _ 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 _ 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 _ Tests whether the private keys that correspond to the specified _pubkey_ files are us‐ able by performing sign and verify operations on each. ### -t _ 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)](https://www.chedong.com/phpMan.php/man/sshdconfig/5/markdown). ### -v is helpful in debugging problems. Multiple **-v **options increase the verbosity. The maximum is 3. ### -X ### -x ## 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)](https://www.chedong.com/phpMan.php/man/ssh/1/markdown), [_ssh-agent_(1)](https://www.chedong.com/phpMan.php/man/ssh-agent/1/markdown), [_ssh-askpass_(1)](https://www.chedong.com/phpMan.php/man/ssh-askpass/1/markdown), [_ssh-keygen_(1)](https://www.chedong.com/phpMan.php/man/ssh-keygen/1/markdown), [_sshd_(8)](https://www.chedong.com/phpMan.php/man/sshd/8/markdown) ## 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)](https://www.chedong.com/phpMan.php/man/SSH-ADD/1/markdown)