firewalk active reconnaissance network security tool

Hacking Truth

So today we will know about the open source tool that helps in active reconnaissance network security. This tool is very amazing, as you can tell -_- you can help us by subscribing to our youtube channel :. Kumar Atul Jaiswal .: before using the too.

The firewalk tool is an active reconnaissance network security tool that helps us to figure out what level 4 protocols will pass or deny in our router or firewall. It attempts to scan what protocols will allow and what it will block.
This tool is Really very useful during pentest to check firewalls in a corporate environment. firewalk active reconnaissance network security tool

How Does FIREWALK work

Firewalk attempts to determine which protocols a router or firewall will block and which they will pass on to downstream hosts. It operates on an IP expiry technique, much like the commonly used Traceroute program.

The IP expiry technique involves manipulating the time to live (TTL) field of the IP header to map out all intermediate routers or hops between a scanning host and the target host. In Firewalk, scans are then sent with a TTL value one hop higher than that of the target host.

If the scan packets are blocked by an ACL or firewall, they are dropped or rejected. If allowed to pass through, they will expire and elicit an ICMP time exceeded message.

Based upon the results of the scans, Firewalk can identify which ports are open.

Firewalk is not pre-installed in Kali Linux's newer versions but we don't need to to clone from github this tool available in Kali Linux repository so open terminal and type following command to update our Kali.

apt-get update

After updating complete we will need to install our this tutorials tool firewalk. This is also very easy. Type following command in terminal linux :

apt-get install firewalk -y

After installation process complete we are going to run this tool. We can use following command to run filewalk:

firewalk -S 1-23 -i usb0

I have tested this in my own system and the screenshot is this command is following :

In the above command -S is for specifying the port numbers we want to test and -i is for specifying the interface of network like wlan0 eth0 etc.

you can check which interface network do you use


To check other option of this tool run following command in terminal window.

firewalk -h

Script Arguments


maximum number of ports to probe per protocol. Set to -1 to scan every filtered port.

the maximum number of allowed retransmissions.

the duration of the packets capture loop (in milliseconds).

maximum number of parallel active probes.

validity period of a probe (in milliseconds).

Example Usage

  • nmap --script=firewalk --traceroute <host>
  • nmap --script=firewalk --traceroute --script-args=firewalk.max-retries=1 <host>
  • nmap --script=firewalk --traceroute --script-args=firewalk.probe-timeout=400ms <host>
  • nmap --script=firewalk --traceroute --script-args=firewalk.max-probed-ports=7 <host>

Script Output

| firewalk:
| 2  tcp       21-23,80
|                  udp       21-23,80
| 6     tcp       67-68
| 7   tcp       25
|_                 udp       25


This was written for educational purpose and pentest only.
The author will not be responsible for any damage ..!
The author of this tool is not responsible for any misuse of the information.
You will not misuse the information to gain unauthorized access.
This information shall only be used to expand knowledge and not for causing  malicious or damaging attacks. Performing any hacks without written permission is illegal ..!

All video’s and tutorials are for informational and educational purposes only. We believe that ethical hacking, information security and cyber security should be familiar subjects to anyone using digital information and computers. We believe that it is impossible to defend yourself from hackers without knowing how hacking is done. The tutorials and videos provided on is only for those who are interested to learn about Ethical Hacking, Security, Penetration Testing and malware analysis. Hacking tutorials is against misuse of the information and we strongly suggest against it. Please regard the word hacking as ethical hacking or penetration testing every time this word is used.

All tutorials and videos have been made using our own routers, servers, websites and other resources, they do not contain any illegal activity. We do not promote, encourage, support or excite any illegal activity or hacking without written permission in general. We want to raise security awareness and inform our readers on how to prevent themselves from being a victim of hackers. If you plan to use the information for illegal purposes, please leave this website now. We cannot be held responsible for any misuse of the given information.

- Hacking Truth by Kumar Atul Jaiswal

Video Tutorial :-  SooN


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