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I have seen a lot of of WebRTC client libraries using public STUN server like below:

"stun.l.google.com:19302",
"stun1.l.google.com:19302",
"stun2.l.google.com:19302",                                                                                                                              
"stun3.l.google.com:19302",
"stun4.l.google.com:19302",

I am wondering if the servers above are dead? Because I have tried:

telnet stun.l.google.com 19302
telnet stun.l.google.com 3478

I get the following response:

telnet: connect to address 74.125.204.127: Operation timed out
telnet: Unable to connect to remote host

Same thing happens to other google STUN server in list.

I couldn't get any response, does this mean the STUN servers from Google is not usable anymore?

My question is: Is telnet like the above the correct way to determine if a service is alive or not?

6
  • 4
    I'm voting to close this question as off-topic because is should be addressed to Google.
    – EEAA
    Jul 22, 2015 at 11:57
  • 10
    Actually, it is a good question, even though it's specific to Google. And a good answer will provide a way to test a STUN server in general. Moreover that STUN server is used in any WebRTC samples, demos, tutorials etc. I think people are too hasty in downvoting questions without REALLY understanding them and knowing what it's about.
    – Adrian Ber
    Nov 2, 2015 at 19:52
  • @AdrianBer this is a good question, I also wanted to know the same Jan 25, 2017 at 9:55
  • Answer: stackoverflow.com/a/34033938
    – A T
    Oct 16, 2017 at 12:27

1 Answer 1

16

I receive a reply when sending a STUN packet to port 19302 on stun.l.google.com.

Your telnet command gets no reply because it is not speaking STUN. It will attempt to open a TCP connection, which fails because STUN is running over UDP not TCP.

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