Viewed k times. Improve this question. HBruijn Accordingly, we have a dedicated wiki entry on the topic. Many of the problems are likely elsewhere, albeit hopefuily on a smaller scale. Debugging connection problems in a node cluster is not fun. Your dedicated wiki entry link points to this question ; — user Here is the official link: wiki. I'll add a cross reference back from there to here for that full loop though. FWIW, that wiki link is added to ConnectionRefused exceptions passed up in the Hadoop stack, along with the extra info hosts, ports needed to work out what is going wrong.
We still get lots of bug reports from people who see the stack trace and don't follow the link to the wiki — stevel. Show 4 more comments. Active Oldest Votes. The message 'Connection Refused' has two main causes: Nothing is listening on the IP:Port you are trying to connect to. The port is blocked by a firewall.
No process is listening. Port is blocked by a firewall If the port is blocked by a firewall and the firewall has been configured to respond with icmp-port-unreachable this will also cause a connection refused message. Improve this answer. ELI5 version: it means the connection request got to the other computer, and the other computer had no clue what you were talking about. In my case, something was listening… but on a different node that the one I was attempting to connect to.
Ok, so ufw is definitely allowing connections on port 80 and nginx is definity listening on port You do this by listening on 0. Note: --bind 0. Other servers will have other ways of specifying this. For example, for a Flask application packaged with a Dockerfile , you can do:.
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There are four pieces of information needed to run SSH:. Any open port is a security vulnerability, as hackers can try to exploit it and gain access to the server. For this reason, unused ports are often closed to prevent attacks. In the event that port 22, or the custom SSH port for your server, has been closed, you will likely see a Connection refused error.
You can see all the ports listening on your server by running this command:. As we briefly mentioned earlier, servers use SSH daemons to listen for and accept connections.
Generally speaking, almost all hosting providers will have SSH daemons installed on their servers by default.
This particular issue is more common on localhost or dedicated servers. Since open ports present a security risk, firewalls installed to protect servers from hackers sometimes block connections to them. Unfortunately, this means that even harmless users who are trying to SSH into their servers may receive a Connection refused error as a result of firewall settings.
You can display them in your command-line interface with the following commands:.
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