I recently tried Sheilds Up! at https://www.grc.com/x/ne.dll?bh0bkyd2 . I ran three tests - File Sharing, Common Ports and All Service Ports. The File Sharing report showed that port 139 does not appear to exist, and that it was not possible to connect with NetBIOS to my computer. As far as I can see, I passed here with flying colors. The Common Ports report said that I passed on solicited and unsolicited TCP packets. I failed the Ping Reply (ICMP echo) test. The All Service Ports report showed only green ports - status "stealth". Including ports 20 and 21, which is interesting because of what I discovered afterwards. Since the File Sharing report showed that I didn´t pass the ping test, and that firewalls often could be configured to take care of this, I checked out the firewall on OS X, to see what I could do. What I found was that everything appeared to be off - including FTP - when I viewed the Service panel. But when I go to FTP in the Firewall panel, it says that ports 20 and 21 are open. But according to the All Service Ports report, both ports 20 and 21 passed as Stealth/green. (I could identify specific ports by hovering the mouse above each block in the report, and confirmed that these ports were stealth.) When I go over to the Firewall panel and highlight FTP Access, it says: "Ports 20 and 21 are open. If others connect to your computer from Ports 20 and 21, then ports 1024 through 65535 are open. When you turn on FTP access in the Services pane, you also allow the service access through the firewall on the indicated ports. To stop access through the firewall, you must turn off this service using the service pane." - despite that fact that the Service Pane states FTP access IS off. I don´t see anything that clearly has to do with pinging in the firewall preferences, but that´s most likely just because I don´t know what to look for. All of this is new for me. Could it be that those two open ports are what´re responding to pings? And if I shut them down (if I can figure out how, since the Service panel says they ARE off), will I still be able to upload using my FTP program (Cyberduck)? I also have a router that has a built-in firewall (D-Link wireless, Dl-514). I never bothered with the software for this, because it more or less worked when I plugged it in. I didn´t want to start messing with something that worked. I´m an interested mac user, but don´t have the technical savvy of a lot of you who post here. What should I do? I tried to post a few screen shots I took of the various things I describe here, but couldn´t for the life of me get them to show up in the previewed post. Hope my descriptions are adequate.