How To Scan UDP Ports
Nmap is one of the most used tools for port scanning. That's why we use Nmap for port scanning. Nmap has a wide variety of parameters and a lot of scripts to work on port scans.
What is UDP Protocol?
UDP (User Datagram Protocol) is a protocol (same as TCP) that defines rules to communicate with other systems in a network. TCP and UDP are both communication protocols in the network layer. But they are different from each other. TCP is connection-oriented, UDP is not. TCP makes sure that the messages reach the destination, UDP doesn't. UDP is used by protocols such as DNS, DHCP, TFTP, SNMP, RIP, VOIP. Also it is faster than TCP.
We scan only top 10 UDP ports. If you want to scan the most used 10 TCP ports, we have another top 10 tcp port scanner for this. Here is top 10 UDP ports.
| Port | Service |
|---|---|
| 53 | DNS |
| 67 | DHCP |
| 123 | Network Time Protocol (NTP) |
| 135 | DCE/RPC |
| 137 | NetBIOS |
| 138 | NetBIOS |
| 161 | SNMP |
| 445 | Microsoft-DS |
| 631 | Internet Printing Protocol (IPP) |
| 1434 | MSSQL |
We can advice you a few to things to do for UDP ports
- If you do not use related service then stop it. Do not increase your attack surface. Stoping unnecessary services is one of the best practices and huge step in hardening operation systems. For example if port 53 open for DNS and you do not using it, stop DNS services.
- You should restrict access. Use either a firewall to allow specific IP addresses for your port if you can. Or change your service settings to make accessible only from localhost.
- Make sure your softwares are up to date. Do not miss any security patches.
- Use strong authentication mechanism. Whole internet are scanning by attackers to detect weak authentication mechanism.
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