Firewalk – Firewall Ruleset Testing Tool


This is another oldskool tool, but still relevant! TCP and UDP still work in the same way and firewalls/edge devices are still often configured wrongly.

Firewalk is an active reconnaissance network security tool that attempts to determine what layer 4 protocols a given IP forwarding device will pass. Firewalk works by sending out TCP or UDP packets with a TTL one greater than the targeted gateway. If the gateway allows the traffic, it will forward the packets to the next hop where they will expire and elicit an ICMP_TIME_EXCEEDED message. If the gateway hostdoes not allow the traffic, it will likely drop the packets on the floor and we will see no response.

To get the correct IP TTL that will result in expired packets one beyond the gateway we need to ramp up hop-counts. We do this in the same manner that traceroute works. Once we have the gateway hopcount (at that point the scan is said to be bound) we can begin our scan.

It is significant to note the fact that the ultimate destination host does not have to be reached. It just needs to be somewhere downstream, on the other side of the gateway, from the scanning host.

Read the original 1998 whitepaper here.

You can download Firewalk here:

firewalk.tar.gz

Or read more here.

Posted in: Hacking News

, , ,


Latest Posts:


APT-Hunter - Threat Hunting Tool via Windows Event Log APT-Hunter – Threat Hunting Tool via Windows Event Log
APT-Hunter is a threat hunting tool for windows event logs made from the perspective of the purple team mindset to provide detection for APT movements hidden in the sea of windows event logs.
GitLab Watchman - Audit Gitlab For Sensitive Data & Credentials GitLab Watchman – Audit Gitlab For Sensitive Data & Credentials
GitLab Watchman is an app that uses the GitLab API to audit GitLab for sensitive data and credentials exposed internally, this includes code, commits, wikis etc
GKE Auditor - Detect Google Kubernetes Engine Misconfigurations GKE Auditor – Detect Google Kubernetes Engine Misconfigurations
GKE Auditor is a Java-based tool to detect Google Kubernetes Engine misconfigurations, it aims to help security & dev teams streamline the configuration process
zANTI - Android Wireless Hacking Tool Free Download zANTI – Android Wireless Hacking Tool Free Download
zANTI is an Android Wireless Hacking Tool that functions as a mobile penetration testing toolkit that lets you assess the risk level of a network using mobile.
HELK - Open Source Threat Hunting Platform HELK – Open Source Threat Hunting Platform
The Hunting ELK or simply the HELK is an Open-Source Threat Hunting Platform with advanced analytics capabilities such as SQL declarative language, graphing etc
trape - OSINT Analysis Tool For People Tracking Trape – OSINT Analysis Tool For People Tracking
Trape is an OSINT analysis tool, which allows people to track and execute intelligent social engineering attacks in real-time.


2 Responses to Firewalk – Firewall Ruleset Testing Tool

  1. navin October 15, 2008 at 10:21 am #

    i don’t get it….whts so unknown abt it?? don’t all network recon tools work in the same way?? I mean the n+1 TTL ?? I mean atleast tht’s how I think they mostly work…am I right??

  2. Anonymoose October 17, 2008 at 4:00 pm #

    @navin:
    That’s the point! It’s an old-school tool that still works.