Egress Check NSE Script

Purpose

The egress-check.nse script tests egress filtering by attempting to establish outbound connections from a target machine to an external server over a specified range of ports. This script helps network administrators and security analysts to:

• Identify which outbound ports are permitted by firewalls or network security policies.
• Validate egress filtering rules.
• Detect potential misconfigurations that could allow unauthorized exfiltration of data.

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Features

• Tests multiple ports within a user-defined range.
• Reports ports that allow outbound traffic to a specified external server.
• Configurable through simple arguments: egress-server and egress-ports.

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Example Usage

Command Syntax

nmap <target-ip> --script egress-check --script-args "egress-server=<server-ip>,egress-ports=<start-<end>"

Example Output

PORT     STATE SERVICE
22/tcp   open  ssh
111/tcp  open  rpcbind
443/tcp  open  https
631/tcp  open  ipp
5901/tcp open  vnc-1

Host script results:
|_egress-check: Egress allowed on ports: 22, 111, 443