Nmap Evade Firewall & Scripting [Updated 2018]

Nmap is the most powerful scanner that is used to perform so many functions including port scanning, service detection, and even vulnerability detection. Nmap from beginner to advanced has covered many basic concepts and commands, and in this second part of this series of articles I will discuss some advanced techniques of Nmap.

How to Evade a Firewall/IDS

Firewalls and IDS (intrusion detection systems) normally play an important role to defend the remote target very well from a security point of view because these hardwares and softwares are capable of blocking the intrusion, but in the case of penetration testing you need to bypass these tools to get the right result otherwise you will be misled. Nmap can scan the firewall and other intrusion detection systems on the remote target computer, as it uses different types of techniques to fight against these softwares and the techniques are dependent on the remote software. There are two types of firewall that might be installed on the target computer:

  • Host based firewall (A firewall is running on a single target computer, for example you are running a firewall on your computer)
  • Network based firewall (A firewall has been installed and is running to protect the entire network and has been deployed at the node of the network, it might be LAN)

There are two types of IDS/IPS also available that might be installed on the target machine, this is the situation that a penetration tester needs to tackle. There are so many different type of Nmap techniques that can be used in this situation, for example:

TCP ACK Scan (-sA)

It is always good to send the ACK packets rather than the SYN packets because if there is any active firewall working on the remote computer then because of the ACK packets the (Read more...)

*** This is a Security Bloggers Network syndicated blog from InfoSec Resources authored by Irfan Shakeel. Read the original post at: