Open Door Networks today released DoorStop 1.0, a software-based firewall that promises to improve security on Macintosh-based Internet servers, particularly those providing AppleShare-over-IP services via Open Door’s ShareWay IP. Operating only on the Macintosh on which it is installed, DoorStop enables you to block or grant access to specific TCP services – see "Open Door Slams Network Doors" in TidBITS 444 for more details. DoorStop requires a PowerPC-based Macintosh, Mac OS 8.1, and Open Transport 1.3 or later. Single copies of DoorStop cost $299 or $199 for education customers; various other volume and site licenses available. You can download a 680K free evaluation version.