My parents live way out in the middle of nowhere. The only service provider that is not satellite is Century Link, which uses ADSL / phone lines.

They wanted me to set them up, and the service guy was trying to charge them a rental fee per month for the modem; I dug around in their "old technology" bin and found a Westell Model 6100. Now, it doesn't look like this modem has gotten a software update for A LONG time. Last software update was 2012 from my research.

However, there is a way to put the modem in transparent bridge mode. So, I bought them a Asus AC1300 as a router.

I pass the internet connection along via transparent bridge mode to the router. This requires the router to have the PPOE password, but essentially nothing else sensitive.

The router has updated security settings (Firewall, NAT, etc). I configured it to be fairly strict while still allowing their devices to work properly.

Also note: I changed the default password for both the router and the modem.

Is this putting them at risk from a security standpoint?

I don't know a lot about networking, but I know out of date devices are bad. That said, it was my understanding that a modem itself does not contain security features; security features are controlled from the router.

One other thing worth mentioning: the modem technically did have a NAT, but once you put it in transparent bridge mode, it removes the nat and passes the public IP straight to the router. The router then uses that as the WAN IP.

1 Answer 1


I don't know if the modem has itself bugs which might affect its security even when configured as a dumb DSL modem (i.e. bridge mode). But due to NAT the internal network should be save from direct attacks from this modem. Security issues in the modem might though result in traffic modification and can thus indirectly affect the internal network. But the attack surface when used as dump DSL modem is likely way smaller so I think that this network setup is sufficiently secure.

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