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UDP Port Scanner with Nmap

Discover open UDP ports, detect service version and operating system

This scanner detects open UDP ports on target systems using Nmap. You can find open services such as DNS, VPN, SNMP, NTP and others. The Light version of the scanner finds the most common Top 100 UDP ports and also detects their service version (-sV).
If you want to scan custom UDP ports, please check the Full Scan.

Sample Report | Use Cases | Technical Details

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Sample Report

Here is a UDP Port Scanner with Nmap sample report:

  • Shows the open UDP ports, services and version information
  • Includes operating system information and reverse DNS results
  • The original Nmap output is also included

Download Sample Report

Sample report

UDP Port Scanner with Nmap - Use Cases

Allows you to discover which UDP ports are open on your target host, identify the service versions, and detect the operating system.

Network Penetration Testing

The scanner is helpful for quick port scans but also for lengthy scans which can take multiple hours. The results are accurate since our servers have direct Internet connection. Furthermore, the scanner is optimized for best performance and quality results.

Self-Security Assessment

Check if your servers exposed to the Internet have unnecessary open UDP ports. By also looking at the service versions, you can find which server software is outdated and needs to be upgraded.

Asset Inventory

You can scan IP addresses to map the live hosts and UDP services exposed to the Internet. Find which machines are old and could be used by attackers to break the perimeter and gain access to the internal network.

Technical Details


UDP is a transport layer protocol (the same as TCP) mainly used in network services such as DNS, NTP, DHCP, RTSP, TFTP, and others.

Even though UDP services are less popular than TCP services, having a vulnerable UDP service exposes the target system to the same risk as having a vulnerable TCP service. Hence, discovering all open UDP ports is important in a penetration test for achieving complete coverage of the security evaluation.


Parameter Description
Target This is the target to scan for open UDP ports. Can be specified as hostname or IP address
Ports to scan - Common This option tells Nmap to scan only the top 10, 100, 1000, or 5000 most common UDP ports (Nmap --top-ports). Top 100 is the default scan option.
Ports to scan - Range You can specify a range of ports to be scanned. Valid ports are between 1 and 65535. Because of the way UDP protocol works, scanning is pretty slow so if you specify a large range of ports, the scan can take up to several hours.
Ports to scan - List You can specify a comma-separated list of ports to be scanned
Detect service version In this case, Nmap will try to detect the version of the service that is running on each open port. In the case of UDP, this is possible only by sending UDP requests that can be understood by the tested service, otherwise, the service will not answer at all
Detect operating system If enabled, Nmap will try to determine the type and version of the operating system that runs on the target host. The result is not always 100% accurate, depending on the way the target responds to probe requests
Don't ping host If enabled, Nmap will no longer do host discovery before scanning (which is the default behavior). This option is useful when the target host does not respond to ICMP requests but it is up and it has open ports

How it works

The tool is a web interface for Nmap, which is called with the proper parameters to provide speed and accuracy.

Behind the curtains, Nmap sends UDP packets to each port specified in the parameters. If the target responds with 'ICMP port unreachable', Nmap can be sure that the port is closed. Otherwise (no response received), the scanner cannot know if the port is open, firewalled or if the packet was lost on the way. In this case, Nmap will show you the status open|filtered for that port.

To make sure that a certain port marked as open|filtered is really open, you should enable the detection of the service version. Since this operation is really slow, you should do it in a second scan, only for the ports that were reported as open|filtered in the initial simple scan.