121 lines
3.9 KiB
Plaintext
121 lines
3.9 KiB
Plaintext
---
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layout: docs
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page_title: One-Time SSH Passwords (OTP) - SSH - Secrets Engines
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description: |-
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The One-Time SSH Password (OTP) SSH secrets engine type allows a Vault server
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to issue a One-Time Password every time a client wants to SSH into a remote
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host using a helper command on the remote host to perform verification.
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---
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# One-Time SSH Passwords
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The One-Time SSH Password (OTP) SSH secrets engine type allows a Vault server to
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issue a One-Time Password every time a client wants to SSH into a remote host
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using a helper command on the remote host to perform verification.
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An authenticated client requests credentials from the Vault server and, if
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authorized, is issued an OTP. When the client establishes an SSH connection to
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the desired remote host, the OTP used during SSH authentication is received by
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the Vault helper, which then validates the OTP with the Vault server. The Vault
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server then deletes this OTP, ensuring that it is only used once.
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Since the Vault server is contacted during SSH connection establishment, every
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login attempt and the correlating Vault lease information is logged to the audit
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secrets engine.
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See [Vault-SSH-Helper](https://github.com/hashicorp/vault-ssh-helper) for
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details on the helper.
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This page will show a quick start for this secrets engine. For detailed
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documentation on every path, use `vault path-help` after mounting the secrets
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engine.
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### Drawbacks
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The main concern with the OTP secrets engine type is the remote host's
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connection to Vault; if compromised, an attacker could spoof the Vault server
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returning a successful request. This risk can be mitigated by using TLS for the
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connection to Vault and checking certificate validity; future enhancements to
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this secrets engine may allow for extra security on top of what TLS provides.
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### Mount the secrets engine
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```shell-session
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$ vault secrets enable ssh
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Successfully mounted 'ssh' at 'ssh'!
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```
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### Create a Role
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Create a role with the `key_type` parameter set to `otp`. All of the machines
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represented by the role's CIDR list should have helper properly installed and
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configured.
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```shell-session
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$ vault write ssh/roles/otp_key_role \
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key_type=otp \
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default_user=username \
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cidr_list=x.x.x.x/y,m.m.m.m/n
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Success! Data written to: ssh/roles/otp_key_role
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```
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### Create a Credential
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Create an OTP credential for an IP of the remote host that belongs to
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`otp_key_role`.
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```shell-session
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$ vault write ssh/creds/otp_key_role ip=x.x.x.x
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Key Value
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lease_id ssh/creds/otp_key_role/73bbf513-9606-4bec-816c-5a2f009765a5
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lease_duration 600
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lease_renewable false
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port 22
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username username
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ip x.x.x.x
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key 2f7e25a2-24c9-4b7b-0d35-27d5e5203a5c
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key_type otp
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```
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### Establish an SSH session
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```shell-session
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$ ssh username@x.x.x.x
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Password: <Enter OTP>
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username@x.x.x.x:~$
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```
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### Automate it!
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A single CLI command can be used to create a new OTP and invoke SSH with the
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correct parameters to connect to the host.
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```shell-session
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$ vault ssh -role otp_key_role -mode otp username@x.x.x.x
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OTP for the session is `b4d47e1b-4879-5f4e-ce5c-7988d7986f37`
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[Note: Install `sshpass` to automate typing in OTP]
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Password: <Enter OTP>
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```
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The OTP will be entered automatically using `sshpass` if it is installed.
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```shell-session
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$ vault ssh -role otp_key_role -mode otp -strict-host-key-checking=no username@x.x.x.x
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username@<IP of remote host>:~$
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```
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Note: `sshpass` cannot handle host key checking. Host key checking can be
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disabled by setting `-strict-host-key-checking=no`.
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## Tutorial
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Refer to the [SSH Secrets Engine: One-Time SSH
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Password](https://learn.hashicorp.com/vault/secrets-management/sm-ssh-otp) tutorial
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to learn how to use the Vault SSH secrets engine to secure authentication and authorization for access to machines.
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## API
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The SSH secrets engine has a full HTTP API. Please see the
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[SSH secrets engine API](/api-docs/secret/ssh) for more
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details.
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