1SSH-ADD(1) BSD General Commands Manual SSH-ADD(1)
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4 ssh-add — adds private key identities to the OpenSSH authentication agent
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7 ssh-add [-cDdKkLlqvXx] [-E fingerprint_hash] [-H hostkey_file]
8 [-h destination_constraint] [-S provider] [-t life] [file ...]
9 ssh-add -s pkcs11
10 ssh-add -e pkcs11
11 ssh-add -T pubkey ...
12
14 ssh-add adds private key identities to the authentication agent,
15 ssh-agent(1). When run without arguments, it adds the files
16 ~/.ssh/id_rsa, ~/.ssh/id_ecdsa, ~/.ssh/id_ecdsa_sk, ~/.ssh/id_ed25519,
17 ~/.ssh/id_ed25519_sk, and ~/.ssh/id_dsa. After loading a private key,
18 ssh-add will try to load corresponding certificate information from the
19 filename obtained by appending -cert.pub to the name of the private key
20 file. Alternative file names can be given on the command line.
21 If any file requires a passphrase, ssh-add asks for the passphrase from
23 the user. The passphrase is read from the user's tty. ssh-add retries
24 the last passphrase if multiple identity files are given.
25 The authentication agent must be running and the SSH_AUTH_SOCK environ‐
27 ment variable must contain the name of its socket for ssh-add to work.
28 The options are as follows:
30 -c Indicates that added identities should be subject to confirmation
32 before being used for authentication. Confirmation is performed
33 by ssh-askpass(1). Successful confirmation is signaled by a zero
34 exit status from ssh-askpass(1), rather than text entered into
35 the requester.
36 -D Deletes all identities from the agent.
38 -d Instead of adding identities, removes identities from the agent.
40 If ssh-add has been run without arguments, the keys for the de‐
41 fault identities and their corresponding certificates will be re‐
42 moved. Otherwise, the argument list will be interpreted as a
43 list of paths to public key files to specify keys and certifi‐
44 cates to be removed from the agent. If no public key is found at
45 a given path, ssh-add will append .pub and retry. If the argu‐
46 ment list consists of “-” then ssh-add will read public keys to
47 be removed from standard input.
48 -E fingerprint_hash
50 Specifies the hash algorithm used when displaying key finger‐
51 prints. Valid options are: “md5” and “sha256”. The default is
52 “sha256”.
53 -e pkcs11
55 Remove keys provided by the PKCS#11 shared library pkcs11.
56 -H hostkey_file
58 Specifies a known hosts file to look up hostkeys when using des‐
59 tination-constrained keys via the -h flag. This option may be
60 specified multiple times to allow multiple files to be searched.
61 If no files are specified, ssh-add will use the default
62 ssh_config(5) known hosts files: ~/.ssh/known_hosts,
63 ~/.ssh/known_hosts2, /etc/ssh/ssh_known_hosts, and
64 /etc/ssh/ssh_known_hosts2.
65 -h destination_constraint
67 When adding keys, constrain them to be usable only through spe‐
68 cific hosts or to specific destinations.
69 Destination constraints of the form ‘[user@]dest-hostname’ permit
71 use of the key only from the origin host (the one running
72 ssh-agent(1)) to the listed destination host, with optional user
73 name.
74 Constraints of the form ‘src-hostname>[user@]dst-hostname’ allow
76 a key available on a forwarded ssh-agent(1) to be used through a
77 particular host (as specified by ‘src-hostname’) to authenticate
78 to a further host, specified by ‘dst-hostname’.
79 Multiple destination constraints may be added when loading keys.
81 When attempting authentication with a key that has destination
82 constraints, the whole connection path, including ssh-agent(1)
83 forwarding, is tested against those constraints and each hop must
84 be permitted for the attempt to succeed. For example, if key is
85 forwarded to a remote host, ‘host-b’, and is attempting authenti‐
86 cation to another host, ‘host-c’, then the operation will be suc‐
87 cessful only if ‘host-b’ was permitted from the origin host and
88 the subsequent ‘host-b>host-c’ hop is also permitted by destina‐
89 tion constraints.
90 Hosts are identified by their host keys, and are looked up from
92 known hosts files by ssh-add. Wildcards patterns may be used for
93 hostnames and certificate host keys are supported. By default,
94 keys added by ssh-add are not destination constrained.
95 Destination constraints were added in OpenSSH release 8.9. Sup‐
97 port in both the remote SSH client and server is required when
98 using destination-constrained keys over a forwarded ssh-agent(1)
99 channel.
100 It is also important to note that destination constraints can
102 only be enforced by ssh-agent(1) when a key is used, or when it
103 is forwarded by a cooperating [22mssh(1). Specifically, it does not
104 prevent an attacker with access to a remote SSH_AUTH_SOCK from
105 forwarding it again and using it on a different host (but only to
106 a permitted destination).
107 -K Load resident keys from a FIDO authenticator.
109 -k When loading keys into or deleting keys from the agent, process
111 plain private keys only and skip certificates.
112 -L Lists public key parameters of all identities currently repre‐
114 sented by the agent.
115 -l Lists fingerprints of all identities currently represented by the
117 agent.
118 -q Be quiet after a successful operation.
120 -S provider
122 Specifies a path to a library that will be used when adding FIDO
123 authenticator-hosted keys, overriding the default of using the
124 internal USB HID support.
125 -s pkcs11
127 Add keys provided by the PKCS#11 shared library pkcs11.
128 -T pubkey ...
130 Tests whether the private keys that correspond to the specified
131 pubkey files are usable by performing sign and verify operations
132 on each.
133 -t life
135 Set a maximum lifetime when adding identities to an agent. The
136 lifetime may be specified in seconds or in a time format speci‐
137 fied in sshd_config(5).
138 -v Verbose mode. Causes ssh-add to print debugging messages about
140 its progress. This is helpful in debugging problems. Multiple
141 -v options increase the verbosity. The maximum is 3.
142 -X Unlock the agent.
144 -x Lock the agent with a password.
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148 DISPLAY, SSH_ASKPASS and SSH_ASKPASS_REQUIRE
149 If ssh-add needs a passphrase, it will read the passphrase from
150 the current terminal if it was run from a terminal. If ssh-add
151 does not have a terminal associated with it but DISPLAY and
152 SSH_ASKPASS are set, it will execute the program specified by
153 SSH_ASKPASS (by default “ssh-askpass”) and open an X11 window to
154 read the passphrase. This is particularly useful when calling
155 ssh-add from a .xsession or related script.
156 SSH_ASKPASS_REQUIRE allows further control over the use of an
158 askpass program. If this variable is set to “never” then ssh-add
159 will never attempt to use one. If it is set to “prefer”, then
160 ssh-add will prefer to use the askpass program instead of the TTY
161 when requesting passwords. Finally, if the variable is set to
162 “force”, then the askpass program will be used for all passphrase
163 input regardless of whether DISPLAY is set.
164 SSH_AUTH_SOCK
166 Identifies the path of a UNIX-domain socket used to communicate
167 with the agent.
168 SSH_SK_PROVIDER
170 Specifies a path to a library that will be used when loading any
171 FIDO authenticator-hosted keys, overriding the default of using
172 the built-in USB HID support.
173
175 ~/.ssh/id_dsa
176 ~/.ssh/id_ecdsa
177 ~/.ssh/id_ecdsa_sk
178 ~/.ssh/id_ed25519
179 ~/.ssh/id_ed25519_sk
180 ~/.ssh/id_rsa
181 Contains the DSA, ECDSA, authenticator-hosted ECDSA, Ed25519, au‐
182 thenticator-hosted Ed25519 or RSA authentication identity of the
183 user.
184 Identity files should not be readable by anyone but the user. Note that
186 ssh-add ignores identity files if they are accessible by others.
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189 Exit status is 0 on success, 1 if the specified command fails, and 2 if
190 ssh-add is unable to contact the authentication agent.
191
193 ssh(1), ssh-agent(1), ssh-askpass(1), ssh-keygen(1), sshd(8)
194
196 OpenSSH is a derivative of the original and free ssh 1.2.12 release by
197 Tatu Ylonen. Aaron Campbell, Bob Beck, Markus Friedl, Niels Provos, Theo
198 de Raadt and Dug Song removed many bugs, re-added newer features and cre‐
199 ated OpenSSH. Markus Friedl contributed the support for SSH protocol
200 versions 1.5 and 2.0.
201BSD February 4, 2022 BSD