How can I find out what operating system is running on a remote web server?

At times we wish to know the remote server's operating system. It may be important to access the OS with which we are connecting for understanding the type of vulnerabilities and threats we are exposed to by connecting to a particular system. The operating system that you are using is LINUX. In Linux you can use a command line to view the remote server operating system. Use the following command

# nmap -O -v localhost
# nmap -O -v server.ip.address

The output of the above mentioned command will be multiline output. If a through reading is done you will find information about the operating system on the remote computer.

Besides the above command there are also tools available to do so. You can use Telnet or FTP and establish a session with the remote server. This session may give you inputs on the remote system operating system.

Besides there are various fingerprinting software also available. You can use them for this purpose. The basic of this method is the time difference in response by different OS. So, it reads the time when you send the packet and based on the time when the packet was received a probable answer is given.