I spent about 150 hours working on this, until all the necessary access to the production network was addressed. Or so I thought. We applied the firewall access rules during our change control window on Thursday evening. I spent Friday morning, the weekend and now all this week addressing the access issues that folks either didn't think about or didn't address during the meetings I held with the different departments. What Went Wrong For certain applications, it's important to know which ports need to be allowed through the firewall for a certain function.
Ports are channels by which services on the Internet operate.
For example, SSH listens on Port 22. In order for SSH to connect to a server, the firewall must allow communication through Port 22. Web access needs Port 80 opened. Sendmail, which is used for e-mail, runs on Port 25. Each standard service runs on a specified port, and there are 65,535 available ports on the Internet.