Banner Grabbing is a thing which contains the information of a running service. To be simple if we try to connect to a port then it responds to the request made and the Header of the packet is sent by the service in response that contains the information of the service this is known as Banner Using Nmap.
What is Banner Grabbing?
Banner grabbing is a technique used to glean information about a computer system on a network and the services running on its open ports. Administrators can use this to take inventory of the systems and services on their network.
However, an intruder can use banner grabbing in order to find network hosts that are running versions of applications and operating systems with known exploits
Banners can reveal a lot of sensitive information about the services running on the target machine.
For example if you are able to grab banner for FTP protocol you may find out the FTP Client in use by the target machine. This type of information about the services will help us to choose the right exploits.
How to Perform Banner grabbing?
Tools used to perform Banner Grabbing: Telnet,nmap,zmap& NetCat
STEP 1: Performing Port Scan on the Target Machine with NMAP, we need to know the open ports on the target before grabbing the banners
STEP 2: Using netcat now we can grab the banner by the command “nc –v ip portnumber” (eg: nc –v 192.168.1.1 80)
NC = netcat, -v = verbose (to show the output in detail)
STEP 3: After getting connected type the following command “GET HTTP 1/1” or “GET HTTP”, you will get the Server Information.
Banner grabbing of FTP
STEP 1: Perform Port scan and check whether FTP port is open
STEP 2: In Terminal Type the command “nc –v ip 21” (21 is the FTP port number) you will get the details of FTP Client.
Banner Grabbing Using Nmap
STEP 1: Use the Command (nmap -sV –script=banner IP) this will give you the complete banner information of all open ports
Using of Nmap will be handy and using netcat you need to do one by one but in case of Nmap, it makes your work faster and easier.
Source & credits
This article provided to www.techincidents.com by Shankara Narayanan Co-Leader at Hackers Day, student TamilNadu Dr. Ambedkar Law University. He is a Penetration Tester & Computer Forensics.
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The experiment described in this article has a study purpose. Tested on any smartphone with Android system and no attack was performed on external sites. We’ve looked at the typical vulnerabilities associated with hacking.