Practical Network Scanning

Detecting firewalls

Firewalls secure small to large infrastructure networks from malicious attacks and unwanted traffic. But it would be wrong to assume that inputting a firewall will solve everything. Vulnerabilities are part of any hardware and software appliance. The biggest vulnerability is a misconfiguration of the firewall. A well-configured, architecturally designed, updated, and well-maintained firewall is almost impossible to penetrate.

There are several methods available that can help you to detect the location of the firewall. A very easy method to locate a firewall is through traceroute (Unix utility) or tracert (Windows utility).  

Let's take a brief look at the background of traceroute and how it works. People commonly say that ...