OK, I've closed my issue with Vulcan testing.
I install firebird 2.0.1 Super server in Fedaro, and the UDF works fine
in UDF directory.
But this UDF still does not work in Vulcan, no matter in bin directory
or UDF directory, I can make a conclusion that Vulcan has not support
udf yet, still in development.
And I also run Vulcan successfully in windows, not support udf dll
either.
Current vulcan can do backup and restore and SQL stuff.
That's it.

Thanks,
Roc