What is Nmap Scan UDP Port?

Nmap, also known as Network Mapper is a tool that is used to check port scanning. Along with it, this free and open-source software also does network mapping and vulnerability checking. The tool scans IP addresses and detects installed applications. It also helps network admins to find out which devices are running on their network. As mentioned already, port scanning is one of the fundamental features of Nmap and thus today’s topic is based on Nmap scan UDP port. In the doc, you will get familiar with how to conduct Nmap check UDP port process and all the information that you require about port scanning including Nmap UDP port scan range, in detail.

What is Nmap Scan UDP Port

What is Nmap Scan UDP Port?

  • Nmap is a tool that is used extensively for UDP port scanning.
  • Vulnerability testing is required to secure a network.
  • This involves infiltrating your network and discovering weaknesses in the same an attacker might do.
  • To scan the UDP port, you can download Nmap on a Debian machine or Ubuntu.
  • Nmap scanning is advantageous due to its improved port mapping file.
  • It provides an extensive association between ports and services.
  • Nmap must be used to scan ports for the servers that are owned by you.

Continue reading to know about Nmap check UDP port.

What is Nmap UDP Port Scan Range?

In a computer, there are a total of 131,070 ports of which 65,535 are UDP and 65,535 are TCP. Nmap is designed to scan only the commonly used 1000 ports by default to save time. For all ports, the Nmap scan will produce a scan for all 65,535 UDP and TCP ports on the target machine.

Also Read: Fix Controller Error on Device IDE Ideport

Nmap Scan All UDP Ports Process

Note: To avoid syntax errors, ensure that your wildcard [*] statement is enclosed in quotes (“ ”).

If you want to scan all UDP ports using Nmap, the tool will produce a scan for 65,535 UDP and TCP ports. The scan will be done on a target machine and will output a list of open ports as well as the services that are running on that specific port.

1. How to Scan Top Ports

Flag: -top-ports [Number]

Command Syntax: nmap –top-ports [Number] [Target]

Description: Perform Nmap scan by providing the specific number of top-ranked ports to scan

Scan top ports flag using the Nmap tool processes only top-ranked scanning. This involves a scan of the most commonly used 50 ports or so. The command with output that is used in UDP Nmap scan for most commonly used ports is:

nmap – top-ports 50

Note: Replace the IP address given in the command above with your target IP address.

You can also perform the scan for 10000 commonly used ports using the Nmap command given below on the target machine:

nmap – top-ports 10000

Note: 10000 does not refer to the range of ports starting from 1 to 10000.

2. How to Scan Specific Ports

Flag: -p

Command Syntax: nmap –p [Port] [Target]

Description: Perform Nmap scan for multiple or a single port

Nmap check UDP port can also be done using the Scan Specific Ports flag under which you can perform a scan for a single port or multiple ports that can be separated by a comma and no spaces. To scan a single port, for example, port 80, use the command provided below:

nmap -p 80

Now, to scan multiple ports, for example, ports 25, 53, 80-500, you can follow the command below:

nmap -p 25,53,80-500

Also Read: Difference between USB 2.0, USB 3.0, eSATA, Thunderbolt, and FireWire ports

3. How to Scan Ports by Protocol

Flag: -p

Additional Flags: U:[UDP Ports],T:[TCP Ports]

Command Syntax: nmap -p U:[UDP Ports],T:[TCP Ports] [Target]

Description: Perform Nmap scan for ports by protocol or port combination

UDP Nmap scan can be done using a specific protocol or port combination as well. Scans by protocol use –p option followed by T: and U: flags. The scan will be done for a specific UDP and TCP port on a target machine. Let us look at the command below for UDP port 53 [DNS] and TCP port 25 [SMTP]:

nmap -sU -sT -p U:53,T:25

Note: Nmap only scans TCP ports by default, therefore, you need to add –sU and –sT flags in the command.

4. How to Scan Ports by Name

Flag: -p

Command Syntax: nmap –p [Port name (s)] [Target]

Description: Perform Nmap scan for the port by name

Nmap UDP port scan range can also be done for a specific port by name [http,ftp,smtp]. You need to make sure that the port name is exact and matches the name specified in the nmap-service file. Nmap-service file can be accessed by Windows users in the c:\Program Files\Nmap\ folder. In the command given below, the scan has been performed for FTP [21] and HTTP [80] ports:

nmap -p ftp,http

Note: In case of multiple ports, separate the name with a comma and not a space.

This command flag also supports wildcard, therefore, you can process it as output:

nmap -p ftp*

5. How to Fast Scan Flag

Flag: -F

Command Syntax: nmap -F[Target]

Description: Perform Nmap scan for the 100 most commonly used ports

Nmap scan UDP port can be performed for 1000 ports by default. However, with Fast Scan Flag, you can reduce this number to 100 commonly used ports. This will provide you with valuable information on the open ports in numerical order while improving time per scan. You can also use an additional flag, -v, which is verbose mode, and add a sequential port scan in real-time.

What is Port Scanning?

While knowing about Nmap UDP port scan range, it is necessary to know about port scanning. Port scanning is a process that helps to connect to a number of sequential ports to get information on which ports are open and what services & operating systems are behind those ports. Ports are numbered addresses that are assigned inside of the operating system that distinguishes traffic for different services or applications. There are different types of services that use different ports by default. For instance, POP3 email uses port 110 and regular web traffic uses port 80.

Also Read: There are no more endpoints available from the endpoint mapper [SOLVED]

How to Identify Common Ports?

JAN23 What is Nmap Scan UDP Port?

Nmap scan UDP port can be performed if you know of some common ports. Some ports are worth knowing in the pool of the vast number of ports. Check the list provided below for the services commonly associated with ports. You can also find suitable ports for the applications that you are trying to configure with their respective documentation. For Nmap check UDP port, have a look at the below list:

  • 20: FTP data
  • 21: FTP control port
  • 22: SSH
  • 23: Telnet (Insecure and is not recommended for most uses)
  • 25: SMTP
  • 43: WHOIS protocol
  • 53: DNS services
  • 67: DHCP server port
  • 68: DHCP client port
  • 80: HTTP – Unencrypted Web traffic
  • 110: POP3 mail port
  • 113: Ident authentication services on IRC networks
  • 143: IMAP mail port
  • 161: SNMP
  • 194: IRC
  • 389: LDAP port
  • 443: HTTPS – Secure web traffic
  • 587: SMTP – message submission port
  • 631: CUPS printing daemon port
  • 666: DOOM – The legacy game has a special port
  • 993: IMAPS (secure email inbox)
  • 995: POP3 (secure email inbox)

Frequently Asked Questions (FAQs)

Q1. Can Nmap scan all UDP ports?

Ans. Yes, Nmap is designed in such a way that it can scan all UDP ports.

Q2. Which command in Nmap scans UDP ports on the target?

Ans. Command nmap –sU helps in performing a UDP scan. With this scan, Nmap sends 0-byte UDP packets to every port on the target system.

Q3. How can I know if my UDP port is open?

Ans. To know if your UDP port is open or not, you can use nmap –sU –p port ip command, if the result comes out to open then the UDP port is open. If the result comes out open or unfiltered, then the UPD port is either closed or filtered.

Q4. What is a port scan?

Ans. A port scan is done to configure which ports on a network are open.

Q5. Is it legal to scan ports?

Ans. If port scanning is conducted unauthorized, then it is strictly prohibited.


We hope that our guide on Nmap scan UDP port helped you out in knowing about Nmap scan, UDP port, and how to scan different UDP ports with this tool. Leave your suggestions and queries in the comments section below.

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