Mystery Router Port Opening

Long time twit listener, first time poster.

I have three (semi) dumb routers with the head router being a modem/router. Suddenly my FingBox tells me TCP Port 30005 is open to the world (an open port checker website confirmed this).

No uPNP is enabled anywhere and I haven’t made any changes. I have checked each router individually.

What do ya reckon caused this ghostly port to open? And how can I close it?

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I’ve seen ISP’s use ports higher up in the range like this to deploy firmware updates. Who is your provider?

knewman may have the indication on this one.

You could ask your ISP first but you could also re-check with a known router if you have another spare to confirm.

VDSL2 with iiNet Australia

Looks like @knewman got it, that port is used bu ISPs for managing devices, and there are 2 exploites that also use it.

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I haven’t got any experience with that particular provider, but the consensus seems to agree with my original theory. If you don’t have access to your edge modem’s configuration to block the port, try contacting iiNet support to see if they’ll close it for you.

However - you may be closing yourself off to firmware updates for your device. Kind of “damned if you do, damned if you don’t” situation.

Thanks guys. I’ll give iiNet a hoy and post back the results in case someone else has my obscure issue.