Download of IPNetSentry 1.4 for Mac was on the developer's website when we last checked. We cannot confirm if there is a free download of this app available.
According to the results of the Google Safe Browsing check, the developer's site is safe. Despite this, we recommend checking the downloaded files with any free antivirus software. The software is included in Security Tools. This Mac application is an intellectual property of Sustainable Softworks.
From the developer:
IPNetSentry is a simple and intelligent security application which protects your Mac from outside Internet intruders. This is particularly important for Mac users who have cable modem, DSL, or another high-speed Internet service where connections can be maintained and left unattended for hours (or days) at a time.
Unlike most other Internet security products, IPNetSentry does not erect barriers for the safe use of your Internet connection.
You may want to check out more Mac applications, such as IPNetSentryX, which might be related to IPNetSentry.