Block access to certain sites when using 3g dongle when ADSL is down

[southafricanrob]

Hi all,
I am wondering if anyone knows of a way to block access to certain websites when using a 3G dongle but not block anything when using ADSL.

The logic is: I have a Point of Sale system that runs off a website and when normal broadband is working everything is hunky dory - but when ADSL goes down, which has been happening a lot for me recently I am pretty stuck without access to my POS. A 3G dongle as a backup is great but I want to be able to block staff from using youtube etc when using the dongle otherwise I'm going to end up with a hefty data bill - in summary reserve 3g use for accessing my POS site only pretty much.

I have a linksys router running DDWRT but not sure how to put PC based restrictions in place when using the USB dongle???

Thanks...

 

[DrJohnZoidberg]

You should be able to assign a new firewall zone to the 3G interface then block all traffic except those that the POS system uses.

 

[southafricanrob]

aha, as in Windows firewall settings?

 

[DrJohnZoidberg]

aha, as in Windows firewall settings?

No, on the router.

 

[Priapus]

As DrJohnZoiberg pointed out - if the router can use a 3G dongle for Internet - on the router you could setup firewall zone for that device and block sites using that connection.

What's the model of the router you have?

 

[southafricanrob]

Hi, its a Linksys WRT54GL running DDDwrt - problem is the dongle will go straight into the PC in question, loads of other people are still connecting to the router and dont want them using the dongle. Although I suppose if the dongle is blocked to all other sites then shouldn't be a problem, dont think that router supports usb dongles though....

 

[sajunky]

If you share dongle connection on PC, then the easiest way is to block traffic on PC. I think DrJohnZoidberg assumed that dongle is on the router.

 

[ginggs]

Hi, its a Linksys WRT54GL running DDDwrt - problem is the dongle will go straight into the PC in question,

Seeing the modem is going straight onto the PC in question it actually makes it quite easy.
You can disable the setting in the modem's dial-up connection to use it as the default gateway, so all traffic will default to going through your router.
You can then make a static route for your POS site to use the dial-up connection.

 

[bdt]

Given the extreme programmability that Mikrotik boxen have, could an RB750UP (with a single-port adsl device in bridge mode to take care of the line side) be used here?

 

[southafricanrob]

thanks guys - will explore the options mentioned above - have also heard great things about the routerboards