Can I determine a rule based upon another state ?
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Hi,
I want to setup some rules such that, for example, traffic can only pass through to a local port if the remote host already has a connection to another local port:
Remote tries to connect to port 1234 - only allowed if they already have a valid connection to port 3456
or
Remote tries to connect to port 1234 - only allowed already a local connection out to remote on port 5678
I have a feeling this isn't possible, but I thought I'd check. If not, does anyone have suggestions what I can use to achieve this ?
Thanks.
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Not possible.
Why would you want that?
For "security"?Set up a VPN if you need secure access.
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Thanks for the clarification.
I'd want it for port-knocking, or for allowing servers which I connect to (and therefore approve) connect back for additional services whilst I'm connected to them.
It's not a scenario that's used too often, but it's nice to be able to handle it.
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Search the forum about port-knocking.
There have been discussions about that, and why it's not such a good idea.