Poking Holes in the Firewall: Egress Testing With AllPorts.Exposed

The post explains the importance of egress filtering and demonstrates how to quickly assess which outbound TCP ports are permitted from a network by scanning the allports.exposed host using simple PowerShell scripts. It shows examples for common port sets and recommends minimizing outbound exposure by allowing only necessary ports, implementing a web proxy, and forcing client web traffic through it to reduce command-and-control risk.