47 lines
2.4 KiB
Markdown
47 lines
2.4 KiB
Markdown
# Check password hook
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This hook allows you to externally check the provided password, its main use case is to allow to easily support things like password+OTP for protocols without keyboard interactive support such as FTP and WebDAV. You can ask your users to login using a string consisting of a fixed password and a One Time Token, you can verify the token inside the hook and ask to SFTPGo to verify the fixed part.
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The same thing can be achieved using [External authentication](./external-auth.md) but using this hook is simpler in some use cases.
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The `check password hook` can be defined as the absolute path of your program or an HTTP URL.
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The expected response is a JSON serialized struct containing the following keys:
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- `status` integer. 0 means KO, 1 means OK, 2 means partial success
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- `to_verify` string. For `status` = 2 SFTPGo will check this password against the one stored inside SFTPGo data provider
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If the hook defines an external program it can read the following environment variables:
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- `SFTPGO_AUTHD_USERNAME`
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- `SFTPGO_AUTHD_PASSWORD`
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- `SFTPGO_AUTHD_IP`
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- `SFTPGO_AUTHD_PROTOCOL`, possible values are `SSH`, `FTP`, `DAV`, `HTTP`
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Previous global environment variables aren't cleared when the script is called. The content of these variables is _not_ quoted. They may contain special characters. They are under the control of a possibly malicious remote user.
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The program must write, on its standard output, the expected JSON serialized response described above.
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If the hook is an HTTP URL then it will be invoked as HTTP POST. The request body will contain a JSON serialized struct with the following fields:
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- `username`
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- `password`
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- `ip`
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- `protocol`, possible values are `SSH`, `FTP`, `DAV`
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If authentication succeeds the HTTP response code must be 200 and the response body must contain the expected JSON serialized response described above.
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The program hook must finish within 30 seconds, the HTTP hook timeout will use the global configuration for HTTP clients.
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You can also restrict the hook scope using the `check_password_scope` configuration key:
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- `0` means all supported protocols.
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- `1` means SSH only
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- `2` means FTP only
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- `4` means WebDAV only
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You can combine the scopes. For example, 6 means FTP and WebDAV.
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You can disable the hook on a per-user basis.
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An example check password program allowing 2FA using password + one time token can be found inside the source tree [checkpwd](../examples/OTP/authy/checkpwd) directory.
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