Posted on

Remote port forwarding on AWS EC2 does not open ports

Long story short, but by default SSH daemon does not open ports to the internets when you make remote port forwarding, e.g. allows to connect to ports from localhost only.
That’s smart, of course.

To allow connecting from the internets to your new ports you need to add changes to sshd config /etc/ssh/sshd_config:

Add there following line:

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GatewayPorts yes

Now when you do

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ssh -v -R 8080:localhost:4000 user@312.434.53.23 -i ~/.ssh/key.pem

You will be able to make a request from outside 🙂

Posted on

Cannot start observer from IEx shell on MacOS?

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iex(8)> :observer.start()
 
14:26:19.123 [error] ERROR: Could not find 'wxe_driver.so' in: /Users/alex/.asdf/installs/erlang/20.0/lib/wx-1.8.1/priv
 
{:error,
{{:load_driver, 'No driver found'},
  [
    {:wxe_server, :start, 1, [file: 'wxe_server.erl', line: 65]},
    {:wx, :new, 1, [file: 'wx.erl', line: 115]},
    {:observer_wx, :init, 1, [file: 'observer_wx.erl', line: 98]},
    {:wx_object, :init_it, 6, [file: 'wx_object.erl', line: 372]},
    {:proc_lib, :init_p_do_apply, 3, [file: 'proc_lib.erl', line: 247]}
  ]}}

This means you don’t have wxWidgets installed.

I have Erlang installed with asdf tool, highly recommended using it for Erlang and Elixir installations.
So if you have Erlang already installed, uninstall it first:

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asdf uninstall erlang 20.3

Then you need to install wxWidgets:

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brew install wxmac

Check whether you have wxWidgets installed correctly:

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wx-config --version

(it should show a version number)

After that you need to install Erlang back:

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asdf install erlang 20.3

Voila, you can start observer from your IEx shell:

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:observer.start()