Doorstop and AutoPush

By: Richard Glaser - Revised: 2006-06-07 devin

Since I recommend removing the OT Auto Push file, here is some more info on an alternative TCP filtering software from Open Door Network.

Is OT Auto Push Support used by any other ASIP function other than TCP filtering? Also, can anyone comment on DoorStop's ability to work without this extension?

Yes, OT Auto Push is only used by TCP Filtering. The way filtering works is that we "push" a filter module on top of the TCP module. When packets come in, the filter module gets a chance to look at the packets and determine whether to let them through or not.

The Mentat stack is designed so that you can easily push any module on top of any other, but the particular code for allowing a module to pushed on top of TCP was not included (and no, I dont remember why). So, we needed a workaround and that was the OT Auto Push extension.

Doorstop works without the OT Auto Push extension because it "pushes" itself much lower down in the stack (on top of IP) and the Mentat code for doing that is still in Open Transport. This allows filtering of UDP packets too.