SSH-ADD(1) | General Commands Manual | SSH-ADD(1) |
ssh-add
— adds
private key identities to the OpenSSH authentication agent
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 ... |
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
-C
-D
-d
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-e
pkcs11-H
hostkey_file-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_constraintDestination 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 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 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
-k
-L
-l
-q
-S
provider-s
pkcs11-T
pubkey ...-t
life-v
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
-x
--apple-use-keychain
-d
, each
passphrase will be removed from it.--apple-load-keychain
DISPLAY
,
SSH_ASKPASS and SSH_ASKPASS_REQUIRE
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
SSH_SK_PROVIDER
APPLE_SSH_ADD_BEHAVIOR
-A
and -K
options used in earlier macOS releases.
These options have been renamed
--apple-load-keychain
and
--apple-use-keychain
respectively. However,
-A
and -K
still behave as
in earlier releases except in the following circumstances. If a security
provider was specified with -S
or
SSH_SK_PROVIDER
, or if
APPLE_SSH_ADD_BEHAVIOR
is set to the value
“openssh”, then ssh-add
uses
standard OpenSSH behavior: the -A
flag is not
recognized and the -K
flag behaves as documented
in the DESCRIPTION section above.
Otherwise, ssh-add
-A
and -K
will behave as
in earlier macOS releases. A warning will be output to standard error
unless APPLE_SSH_ADD_BEHAVIOR
is set to the
value “macos”.
Note: Future
releases of macOS will not support neither -A
nor -K
without setting this environment
variable.
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 is 0 on success, 1 if the specified command fails, and
2 if ssh-add
is unable to contact the authentication
agent.
ssh(1), ssh-agent(1), ssh-askpass(1), ssh-keygen(1), sshd(8)
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.
December 18, 2023 | macOS 14.6 |