Find Open UDP Port

Introduction

In this challenge, you'll investigate a potential security breach by scanning for rogue UDP services on a server. The challenge involves setting up a rogue UDP server listening on port 9995, then using Nmap to perform a UDP scan on localhost, specifically targeting ports 9990-10000. The Nmap scan results are saved to ~/project/udp_scan_results.txt.

The task is to identify and report the open UDP port number within the specified range by printing it to the console. You'll use grep to parse the Nmap output and awk or sed to extract the port number. If no open UDP port is found, you should print "No open UDP port found". The challenge also includes verification steps to ensure the Nmap scan results file exists and contains the expected output.

Skills Graph

Find Open UDP Port

Investigate a potential security breach by scanning for rogue UDP services on the server.

Tasks

• Perform a UDP scan on localhost, specifically targeting ports 9990-10000, using Nmap and save the results to ~/project/udp_scan_results.txt.
• Identify the open UDP port number within the specified range and store it in an environment variable named OPEN_UDP_PORT.

Requirements

1. Use the nmap command to perform the UDP scan.
2. Save the Nmap scan results to a file named udp_scan_results.txt in the ~/project directory.
3. The Nmap command must scan ports 9990 through 10000 on localhost (127.0.0.1).
4. Use grep to parse the udp_scan_results.txt file and identify the open port.
5. Store the smallest open port number in an environment variable named OPEN_UDP_PORT. If no port is open, set the variable to "NONE".

Examples

If port 1234 is open:

echo $OPEN_UDP_PORT
1234

If no UDP port is open within the specified range:

echo $OPEN_UDP_PORT
NONE

Hints

• Remember to use sudo when running Nmap for UDP scanning.
• Use the -sU option in Nmap to specify a UDP scan.
• Use grep to find lines containing open in the Nmap output file.
• Use awk or sed to extract the port number from the grep output.
• Use export OPEN_UDP_PORT=value to set the environment variable.

Summary

In this challenge, the goal is to identify an open UDP port within the range of 9990-10000 on localhost, simulating a security investigation for rogue UDP services. This involves setting up a rogue UDP server using Python, performing a UDP scan using Nmap with the -sU option, and saving the scan results to a file.

The solution requires parsing the Nmap output file using grep to find lines indicating an open port, and then extracting the port number using awk or sed. Finally, the identified open port number is printed to the console, or "No open UDP port found" if no open port is detected within the specified range. The challenge emphasizes the use of Nmap for UDP scanning and text processing tools for analyzing scan results.