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I am doing a connection test from a pod in kubernetes using netcat and telnet and the test from netcat is working fine and not from telnet. The pod runs a nodejs container and the connectivity from nodejs application is also failing.

telnet from every other pod on the same node works fine. I am completely lost on to why this is happening

Teja
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    Can you provide more detail? In particular, what commands are executed where, and how they're failing. – Burak Serdar Dec 23 '19 at 17:27
  • netcat -zv telnet one thing to note here is that running netstat -antp shows this tcp 0 0 10.244.4.244:58016 10.195.209.4:6380 ESTABLISHED 31/telnet as established but telnet does not show anything. All these are run inside the container exec' ing in to them – Teja Dec 23 '19 at 17:45
  • What do you expect the telnet to show? Is it giving an error, or just sitting there waiting input? If the latter, your pod might be expecting some input. – Burak Serdar Dec 23 '19 at 18:07
  • i was expecting the telnet to output saying established connection. its just sitting there waiting as of now. but the same telnet on a different pod says connection terminated by remote host – Teja Dec 23 '19 at 19:59
  • That sounds like the pod drops packages coming to that port. Maybe the iptables would provide a hint? – Burak Serdar Dec 23 '19 at 20:10
  • can you telnet using `kubectl port-forward`? – Matt Dec 24 '19 at 10:35
  • @Burak Serdar so i got to work with an MS engineer opening a support ticket and looks like the network connection is fine. still could not figure out the strange behavior in that pod. there is no service mesh or anything messing with the iptables. we did checked iptables and haven't found anything significant in there. Thanks all for your time. – Teja Dec 24 '19 at 19:15

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