port 8085 open to external tcp traffic BT home hub 4

Question

I have a BT home hub 4 router and I recently scanned it's external IP using nmap (over the internet, not from within the network). Interestingly I found that port 8085 was open and running a TCP service. So I tried connecting within my web browser by typing the ip and port as in:

http://***.***.***.***:8085/

Interestingly an alert type dialog popped up requesting my username and password.

This was a big surprise to me as I have not set up any remote access service or anything like that, and am completely unable to find any reference to this either on the internet or in the BT documentation that came with the router.

Just to clarify this port is not open internally. So:

http://192.168.1.254:8085/

Just hangs and times out the browser.

Can I ask.. is this normal? What does it do and why? Is it a vulnerabillity? Is there a way to switch it off?

Answer 1

I found that port 8085 was open and running a TCP service

You should ask BT.

From a BT community forum post (see below):

I suspect this is the port used by BT for external access but I need confirmation.

...

It could be the TR-069 WAN management system or another BT service running a session on that port.

TR-069 is a standard for the remote management of end-user devices.

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Port 8085 is opened, what does it do?

Even though I have no Port Forwarding enabled on my HH5 I can see port 8085 is open to the outside world.

Zenmap shows the following result:

8085/tcp open tcpwrapped

...

Firstly the port is showing that it has tcpwrapped like functions enabled on the application running behind that port. This means that it potentially has a host_access allow & deny file associated with it.

Therefore the application will only allow certain IP addresses to fully communicate and use the application.

It could be the TR-069 WAN management system or another BT service running a session on that port.

Source Port 8085 is opened, what does it do?