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2 Messages

Monday, April 6th, 2020 4:05 PM

Mystery interface on Pace 5268AC

I have a question about a mysterious interface on my Pace 5268AC, namely what is it and why can I not see/control it?

Below is my setup and how I discovered the interface:

1. I have AT&T Fiber Internet (no phone or tv).

2. I run my own DNS (Bind9) and DHCPD (ISC) internally.

3. I have a Wifi router ethernet connected to the 5268AC (not Cascaded or DMZ+).

4. I have disabled all Wifi on the 5268AC (both 2.4 & 5 GHz).

I understand the 5268AC cannot be configured for bridge mode operation so I have the following setup on the 5268AC:

1. All Wifi disabled.

2. Custom internal network (192.168.5.0)

3. DHCP cannot be disabled on the 5268AC so the range is set to 192.168.5.1 - 192.168.5.1.

4. The 5268AC never assigns the 1 IP available.

I know that I could configure for DMZ+ but I like the idea of traffic passing through two firewalls before it gets to the inside network.

So after the above configuration I see there is an interface (host name "5268ac") requesting a DHCP IP address from my server. I cannot find anywhere in the 5268AC logs or other web pages the MAC address or name of this interface, nor what it is used for. I have denied IP assignment to the requesting MAC address with no noticable affect to my internal network. So, what is this mystery interface, what is it used for, and why can I not control it. I don't like unknown devices on my network!

Many thanks for your thoughts, comments, or guidance.

Community Support

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225.6K Messages

4 years ago

We're here to help clear this up for you, @gddotts!

 

To put it into layman's terms, because of the way you currently have your setup, the Gateway itself is acting as a device on your internet.

This issue could be caused by the device connected requesting DHCP from the network, which then comes out as 5268AC, since that is the device communicating with the internet.

 

The gateway would still be trying to pull 3 address from DHCP. It needs a Broadcast, Network and Router IP, so it's entirely possible it's just the Gateway continuously trying to probe for DHCP for itself.

 

When setting up a 3rd party network host, all it does essentially is declare that the gateway specifically sends the information to a specific device to determine where it needs to go from there. The gateway is still the device sending requests out to the internet and getting them, then directing to your 3rd party router.

 

In terms of why this is occurring, we would not be able to say due to your third party equipment. However, we are able to say with confidence that what you are seeing is the 5268AC itself.

 

We hope this was able to explain what is occurring for you. If you have any further questions, let us know. We will be here to help!

 

Donovan, AT&T Community Specialist

New Member

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2 Messages

Thanks Donovan for the input.

I should have provided more information in my original post...

The custom network (on the 5268AC) of 192.168.5.0 has the router defined (static) as 192.168.5.254 with a subnet mask of 255.255.255.0 which by definition describes the network and associated broadcast address. It is because of this static network configuaration which is the (Edited per community guidelines) of my question. I have no doubt it is the 5268AC requesting the DHCP IP from my server, my question is what interface is requesting it. Since no wifi is enabled and the outside interface gets its network configuration from the upstream AT&T switch and I have defined the inside network there should not be anything left that needs a private IP.

After giving this some thought I suspect it may be a 5268AC internal bridge interface between the wifi and ethernet ports, but I can not verify this becasue nowhere in the 5268AC can those interfaces be viewed or modified. And if this is true then why would the 5268AC need one of my private IP's when it could just as easily be programmed to use another private network (172.16.0.0 or 10.0.0.0) and insert the proper route from inside -> bridge -> outside?

Thanks again,

GDD

(edited)

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