ssh-add
Adds private key identities to the OpenSSH authentication agent
root@kali:~# man ssh-add
SSH-ADD(1) General Commands Manual SSH-ADD(1)
NAME
ssh-add -- adds private key identities to the OpenSSH authentication agent
SYNOPSIS
ssh-add [-CcDdKkLlNqvXx] [-E fingerprint_hash] [-H hostkey_file]
[-h destination_constraint] [-S provider] [-t life] [file ...]
ssh-add -s pkcs11 [-Cv] [certificate ...]
ssh-add -e pkcs11
ssh-add -T pubkey ...
ssh-add -Q
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 and
~/.ssh/id_ed25519_sk. 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 When loading keys into or deleting keys from the agent, process
certificates only and skip plain keys.
-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.
-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 de-
fault identities and their corresponding certificates will be re-
moved. 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 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 desti-
nation-constrained keys via the -h flag. This option may be spec-
ified 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 us-
ing 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 for-
warded 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.
-N When adding certificates, by default ssh-add will request that the
agent automatically delete the certificate shortly after the cer-
tificate's expiry date. This flag suppresses this behaviour and
does not specify a lifetime for certificates added to an agent.
-Q Query the agent for the list of protocol extensions it supports.
Note: not all agents support this query.
-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 in-
ternal 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 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_ecdsa
~/.ssh/id_ecdsa_sk
~/.ssh/id_ed25519
~/.ssh/id_ed25519_sk
~/.ssh/id_rsa
Contains the ECDSA, authenticator-hosted ECDSA, Ed25519, authenti-
cator-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 ver-
sions 1.5 and 2.0.
Debian March 5, 2026 SSH-ADD(1)
ssh-argv0
Replaces the old ssh command-name as hostname handling
root@kali:~# man ssh-argv0
SSH-ARGV0(1) General Commands Manual SSH-ARGV0(1)
NAME
ssh-argv0 -- replaces the old ssh command-name as hostname handling
SYNOPSIS
hostname | user@hostname [-l login_name] [command]
hostname | user@hostname [-afgknqstvxACNTX1246] [-b bind_address]
[-c cipher_spec] [-e escape_char] [-i identity_file] [-l login_name]
[-m mac_spec] [-o option] [-p port] [-F configfile] [-L
port:host:hostport] [-R port:host:hostport] [-D port] [command]
DESCRIPTION
ssh-argv0 replaces the old ssh command-name as hostname handling. If you
link to this script with a hostname then executing the link is equivalent
to having executed ssh with that hostname as an argument. All other argu-
ments are passed to ssh and will be processed normally.
OPTIONS
See ssh(1).
FILES
See ssh(1).
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 ver-
sions 1.5 and 2.0. Natalie Amery wrote this ssh-argv0 script and the as-
sociated documentation.
SEE ALSO
ssh(1)
Debian Project September 7, 2001 SSH-ARGV0(1)