printing yes scanning no HP Officejet 6950

See summary (must be clear)
I tried to get software to be able to scan
message:
HPLIP cannot detect devices in your network. This may be due to existing firewall settings blocking the required ports like (5353/udp). When you are in a trusted network environment, you may open the ports for network services like mdns and slp in the firewall. For detailed steps follow the link.

http://hplipopensource.com/node/375

Can't find the information about the ports in the firewall