Google cloud, curl through ssh gives `Connection refused` for service listening on port-CodePudding

I'm trying to connect to a service running on a google cloud platform VM from the ssh terminal.

The running process is listening on 7076 as shown here:

ced@instance-1:~$ sudo ss -ltn
State        Recv-Q       Send-Q             Local Address:Port              Peer Address:Port       Process       
LISTEN       0            4096               127.0.0.53%lo:53                     0.0.0.0:*                        
LISTEN       0            128                      0.0.0.0:22                     0.0.0.0:*                        
LISTEN       0            128                         [::]:22                        [::]:*                        
LISTEN       0            1024                       [::1]:7076                      [::]:*

I also have the following firewall rule that allows internal connection:


Name                    Type     Targets      Filters                 Protocols/ports  
default-allow-internal  Ingress  Apply to all IP ranges: 10.128.0.0/9 tcp:0-65535, udp:0-65535

When using the command:

    curl -X POST  --data '{"action": "benchmark"}'  localhost:7076

The response is:

    curl: (7) Failed to connect to localhost port 7076: Connection refused

As I understand:

[::1]:7076 means my service is listening to connection on local host only
I connected through ssh and then used curl, which is an internal connection (ie: from localhost)

Therefor I don't see why I cannot connect.

CodePudding user response：

As John Hanley is mention, your application is listening on IPv6, you can identified with the local address and port referred as "[::1]:7076".

The loopback address 0000:0000:0000:0000:0000:0000:0000:0001 is abbreviated to ::1.

To used the IPv6 with a curl is necesary to run as the following esplained on the manual page.

-6: This option is to used only IPv6 protocol.
-g: This option switches off the "URL globbing parser". When you set this option, you can specify URLs that contain the letters {}[] without having them being interpreted by curl itself.