I have ftp in my http proxy allowed target services. The proxy is running in transparent mode. If I visit an ftp site by changing my browser to port 8080, I get the directory listing produced by astaro. If I don't use port 8080 and try to let transparent proxy catch the service, it goes directly via packet filter.
Screenshots
1. Allowed services in http proxy
2. ftp.astaro.com via port 8080
3. ftp.astaro.com via transparent proxy?