On 12/12/2018 11:44, Martin Gregorie wrote:
> As another, slightly paranoid, precaution I have my ADSL router locked up
> really tightly. Its configured to reject all attempts to connect through
> it from the outside. In fact it can't be seen at all from outside: this
> is checked periodically with Gibson Lab's ShieldsUp tool.

And have you checked for "port knocking"?

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