Cannot connect to proxy server remotely.

[Denver Ogaro]

I am running a twisted proxy server on a compute engine instance:

from twisted.web import proxy, http
from twisted.internet import reactor
from twisted.python import log
import sys
log.startLogging(sys.stdout)


class ProxyFactory(http.HTTPFactory):
    protocol = proxy.Proxy


reactor.listenTCP(8080, ProxyFactory())
reactor.run()

I have a firewall rule to allow http connections to port 8080:

allow-proxy 0.0.0.0/0 tcp:8080 Apply to all targets

When I ssh to the VM, set the `http_proxy` environment variable to http://127.0.0.1:8080, and run `wget icanhazip.com`, all works as expected (a file containing the VM's IP address is created in the current directory).

However, when I try to reproduce that remotely (from my laptop, with `http_proxy` set to the VM's static IP address), I am not able to connect (I get a timeout every time).

Anyone know what might be happening here? Same thing happens when I am using squid.

[Kamran (Google Cloud Support)]

In order to be able to help you with this issue, I'd like to ask a few questions:

- What OS is running on your laptop?

- Are you setting http_proxy variable using the correct port (8080) and VM's IP address?

- Try to telnet to the proxy server and see if you are able to connect to it using this protocol:  telnet <VM's static IP> 8080

- What is the output of wget on debug mode ( wget -d icanhazip.com )

- Make sure that your Internet provider or remote firewall is not blocking outgoing traffic to port 8080. You may configure your proxy on a different port and test this.

Please note that allowing access to your proxy server, which is not protected by password, to all IP addresses (0.0.0.0/0) can let anybody connect to it and use your proxy. This may not only impact the security of your VMs, but also it’ll affect your network traffic billing.

Sincerely,

[Denver Ogaro]

Now that you mentioned it, I realize that this has something to do with the fact that I am running Linux within a Virtualbox VM. I was able to connect when outside the VM. Thanks!

On Saturday, February 27, 2016 at 6:39:18 PM UTC-5, Kamran (Google Cloud Support) wrote:

In order to be able to help you, I'd like to ask a few questions: