anchor.diff:            Whether to enable the SFTP subsystem in the SSH daemon.  This
             enables the use of commands such as <command>sftp</command> and
             <command>sshfs</command>.
  +        '';
  +      };
  +
  +      sftpServerExecutable = mkOption {
  +        type = types.str;
  +        example = "internal-sftp";
  +        description = ''
  +          The sftp server executable.  Can be a path or "internal-sftp" to use
  +          the sftp server built into the sshd binary.
           '';
         };
   
  
positive.code:         ''}
  
          ${optionalString cfg.allowSFTP ''
            Subsystem sftp ${cfgc.package}/libexec/sftp-server ${concatStringsSep " " cfg.sftpFlags}
          ''}
  
          PermitRootLogin ${cfg.permitRootLogin}
  
negative.code:       };
  
      services.openssh.moduliFile = mkDefault "${cfgc.package}/etc/ssh/moduli";
      services.openssh.sftpServerExecutable = mkDefault "${cfgc.package}/libexec/sftp-server";
  
      environment.etc = authKeysFiles //
        { "ssh/moduli".source = cfg.moduliFile;
  