SSH-ADD(1) NetBSD 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 environ- ment 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 certifi- cates 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 argu- ment 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 finger- prints. 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 des- tination-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 spe- cific 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 authenti- cation to another host, `host-c', then the operation will be suc- cessful only if `host-b' was permitted from the origin host and the subsequent `host-b>host-c' hop is also permitted by destina- tion 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. Sup- port 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 repre- sented 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. Certifi- cate 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 speci- fied 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 cre- ated OpenSSH. Markus Friedl contributed the support for SSH protocol versions 1.5 and 2.0. NetBSD 10.1 December 18 2023 NetBSD 10.1
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