Ports 139 & 445 are Windows ports.
Port 139 NetBIOS
NetBIOS Session (TCP), Windows File and Printer Sharing
This is one of the most dangerous port on the Internet. All "File and Printer Sharing" on a Windows machine runs over this port. About 10% of all users on the Internet leave their hard disks exposed on this port.
Port 445 SMB
In Windows 2000, Microsoft has created a new transport for SMB over TCP and UDP on port 445. This replaces the older implementation that was over ports 137, 138, 139.
Your Pix should be by default be blocking these inbound. If you block these outbound as well, you will loose browsing capabilities to networks past the internat network. I would say a security conscientious individual would block these outbound as well. It basically boils down to risk assessment. Do your users really need this functionality? What happens if there is an intrusion as a result? etc.
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