You've opened a UDP port on your server but not sure how to check if you can reach it from the outside. When testing TCP ports, you can check with tools like nmap or nc only from the outside, but the nature of UDP is that it doesn't send anything back so you need to monitor the port on the receiving server to see if you receive any packets from the remote server.

centos - Testing UDP port connectivity - Server Fault I am trying to test whether I can get to a particular port on a remote server (both of which I have access to) through UDP. Both servers are internet facing. I am using netcat to have a certain port listening. I then use nmap to check for that port to see if it is open, but it doesn't appear to be. Iptables is turned off. How to check open ports in Linux using the CLI - nixCraft Jul 22, 2019

Mar 20, 2019 · If you want the used port list to be updated automatically, use the below two methods. Method #2: Use CurrPorts Utility to Find Ports in Use Nirsoft Utilities has a pretty neat and lightweight tool called CurrPorts which lists all the ports that are in use by Windows and other programs.

We can use it to: open TCP connections, listen on arbitrary TCP and UDP ports, send UDP packets, do port scanning under both IPv4 and IPv6 and beyond. Using netcat , you can check if a single or multiple or a range of open ports as follows. Port Forwarding is a feature in routers by which external users are able to access a computer from a local network that is behind a router. This means that with this scheme, it is possible to communicate with a computer that is on a local network starting from anywhere in the world using the Internet. UDP is obviously a send-and-forget protocol. For example, during an NMap UDP scan, the only way to definitively prove that a UDP port is open is if you receive a response from that port. Keep in mind that many services may not reply to arbitrary data and require protocol or application-specific requests in order to warrant a response.

Open Port Check Tool - Test Port Forwarding on Your Router

Online Ping, Traceroute, DNS lookup, WHOIS, Port check