Question
cannot connect to a port
- Posted on December 28, 2019
- DigitalOcean Cloud Firewalls
Asked by stewartvince
My droplet has debian os. I have a java application running which tries to exchange data with remote similar applications. This data exchange has previously worked across remote environments where each node has been a hardware node. It uses apache tribes package to exchange peer to peer messages over TCP.
I have set TCP port 4000 as a rule in my firewall and I have been expecting to be able to communicate with my application listening on that port. Netstat reports 4000 to be a listening port.
In the past with my application running on a dedicated remote server, I have been able to connect using telnet from a remote system (in which case my log files respond reporting junk data). Currently, telnet reports “?need to be connected first”
Also, from the droplet command line I issue: echo “some text” > /dev/tcp/127.0.0.1/4000 which invokes “connection refused”
If I use udp instead, there is no error, but still no indication that the data reached my application.
many thanks,
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Hello,
It sounds like that your Java app is binding to
127.0.0.1:4000rather than0.0.0.0:4000so that’s why you can only access it locally from the server itself.To check if this is true you can run:
If you get something like this:
Then you would need to change your application so it binds to
0.0.0.0rather than127.0.0.1, that way you would be able to access it remotely.Let me know how it goes! Regards, Bobby