This is a hook as described in the SFTPGo documentation for external authentication that allows you to validate your SFTPGo users via NetAuth.
It can be enabled by configuring the following environment variables:
SFTPGO_DATA_PROVIDER__EXTERNAL_AUTH_HOOK=/absolute/path/to/sftpgo-hook
SFTPGO_NETAUTH_HOMEDIR=/base/path/for/netauth/users/