Fixed: ARP Table reporting routes for entire /22 subnet

andrew_241 · Feb 8, 2020, 1:41 AM

Re: ARP Table reporting routes for entire /22 subnet

So apparently, this must have been a problem with AT&T's residential gateway device. I replaced the Arris NVG589 with an Arris BGW210-700, and while I think the problem still occurred when initially installed, the latest BGW210 firmware (2.5.6) seems to have fixed it.

johnpoz · Feb 8, 2020, 3:29 AM

Huh? The arp table would not have routes in it ;) It would would have mac address for devices on the L2 networks pfsense is connected to.. Not routes! Did you mean the route table?

And if your connected to /22 then yes it would show routes for that..

See here my wan is /23, so yeah there is a route for that nework since directly attached to that network.

This is arp table

andrew_241 · Feb 8, 2020, 4:16 AM

Thanks for the correction. It was definitely the ARP table. Every IP address in that subnet would be there, and the MAC address in those entries was that of the gateway device. I should have taken a screenshot.

johnpoz · Feb 8, 2020, 11:04 AM

that is still not a route.. But sure if device answers (your modem) for an IP on your network then it would show in the mac address table.

Here I tried pinging a bunch of different addresses in my /23 and you can see them now in my arp table, with the mac address of my modem.

If you had done some sort of scan of /22 then yeah you would of see mac address of your cable modem for all of the IPs.