dial tcp 127.0.0.1:9091: connect: connection refused

Question

I am using gRPC application and building a simple app. Below the files.

syntax = "proto3";
option java_multiple_files = true;
package com.grpc;

message HelloRequest {
    string firstName = 1;
    string lastname = 2;
}
message HelloResponse {
    string greeting = 1;
}
service HelloService {
    rpc hello(HelloRequest) returns (HelloResponse);
}

It generates the file normally

User.java -> generated from protoc compiler
userGrpc.java -> generated from protoc compiler

GRPCService.java

package GRPCService;

import java.io.IOException;

import io.grpc.Server;
import io.grpc.ServerBuilder;
import user.UserService;

public class GPRCService {
    public static void main(String[] args) throws IOException, InterruptedException {
        Server server = ServerBuilder.forPort(9091).addService(new UserService()).build();  
        server.start();
        System.out.println("Server started at " +  server.getPort());
        server.awaitTermination();
    }
}

The system.out.println showing the server is running;

Server started at 9091

And then I opened the firewall rule for TCP on port 9091 on ubuntu 18.04

sudo ufw allow from any to any port 9091 proto tcp

Results:

java      28277    ubuntu   49u  IPv6   478307      0t0  TCP *:9091 (LISTEN)

I can even curl from the terminal

* Rebuilt URL to: http://localhost:9091/
*   Trying 127.0.0.1...
* TCP_NODELAY set
* Connected to localhost (127.0.0.1) port 9091 (#0)
> GET / HTTP/1.1
> Host: localhost:9091
> User-Agent: curl/7.58.0
> Accept: */*
> 
Warning: Binary output can mess up your terminal. Use "--output -" to tell 
Warning: curl to output it to your terminal anyway, or consider "--output 
Warning: <FILE>" to save to a file.
* Failed writing body (0 != 40)
* stopped the pause stream!
* Closing connection 0

Curl command

   curl -v http://localhost:9091

But when executinng from the gui client

https://github.com/gusaul/grpcox

I get a connection refused.

dial tcp 127.0.0.1:9091: connect: connection refused

I am not using any VPN nor proxy and the GUI app is actually running inside a container.

docker run -p 6969:6969 -v {ABSOLUTE_PATH_TO_LOG}/log:/log -d gusaul/grpcox

If somebody could please help me.

Thank you Stack !

Answer 1

If you're running grpcox as a docker container, you'll need to give the container either host network access (easiest) so that it can access the server running on the host's (!) port 9901 i.e. localhost:9901, or provide it with a DNS address that it can resolve the address your host, i.e. your-host:9901.

For host network access, run the container...

docker run --net=host ... gusaul/grpcox

Answer 2

You may need to disable any VPN that you might be using as it was the case for me.

Answer 3

When I was facing this issue on my Kali dial tcp 127.0.0.1:80: connect: connection refused I noticed that my VPN extension is connected on Firefox so I turned it off and everything was normal.