UDP connectivity testing

by Jay Migliaccio




This article is intended for administrators who need to verify that they have UDP connectivity between two systems. Since there are multiple tools for testing UDP connectivity, a few of them are explained here. This article covers the following utilities for testing UDP connectivity: iperf and netcat.


Operating System: Windows, Linux, Mac OS X


Option 1: iperf

Iperf is a free client server utility that can be used to validate UDP connectivity and throughput.

Server setup: Run iperf to listen for UDP traffic on port 33001

iperf -s -p 33001 -u




On the client: Send to the server machine that's listening for UDP on port 33001 (in this case, IP, at 10 Mbs:

iperf -c -u -p 33001 -b 10M




Option 2: Netcat

Netcat is the Swiss Army knife of networking utilities.

 On the server, run netcat in listen mode (-l), and specify UDP (-u) and the port (33001):

# nc -l -u 33001


On the client, specify UDP (-u) and provide the server IP address and port that the server is listening to:

# nc -u ip_address 33001




Once the connection is established - you need to type something in the client window, and press ENTER. If the connection is working, you will see that text in the server window.

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