Take the 2-minute tour ×
Server Fault is a question and answer site for professional system and network administrators. It's 100% free, no registration required.

Is there anything that enables a "telnet-like" functionality for UDP? I know the difference between TCP and UDP, and why telnet itself won't work - but I'm wondering if there is something similar to the telnet client, from the end-user perspective. E.g. udp-telnet [ip] [sending-port] [receiving-port] which then prints out wether a packet made it back or not.

Having a tool like this would proove helpful for testing out firewall settings for OpenVPN which uses UDP connections.

share|improve this question
2  
Note that by the very nature of UDP, it's impossible for a client to know whether a packet was delivered -- the server does not send an acknowledgement of received data on the protocol level. –  josh3736 Jun 4 '12 at 17:06
1  
Also note that in UDP, order of delivery is not guaranteed. That means that the following packets: "cd /". "cd temp", "rm -rf *" could lead to results you might not expect or enjoy. The way routing works, it's likely that the first packet arrives after the second and possibly third--the first often gets held up for a few seconds while routes are resolved--other packets can slip by before it's requeued. –  Bill K Jun 4 '12 at 17:38
add comment

3 Answers 3

up vote 14 down vote accepted

You can use netcat - just start it, and type something inside, and pres the return key.

nc -u <host> <port>

And on the other side you can listen with netcat too (you should see the written text), or just start a tcpdump, and see packets coming in.

share|improve this answer
add comment

You can use netcat or nc. It supports TCP and UDP. Use the -u for UDP sockets. You can read man nc for more details.

share|improve this answer
add comment

In Windows, I use PortQry for this: http://www.microsoft.com/en-us/download/details.aspx?id=17148

share|improve this answer
add comment

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.