There have been a few visitors to this post but no one has replied. I assume none of them knows about this issue.I did some more research on
google and talked to a few friends. It appears that in bridge mode, the firewall of the modem cannot be used at all. The responsibility for firewall then falls on the computer which is connected to the modem and on which the pppoe dialer is installed.Hence, since the better option is to use the builtin firewall of the modem/
router, the best option is to operate the modem in pppoe mode (not in bridge mode). The NAT and firewall of the modem then becomes a very important security layer.For example, when I check the Zone Alarm firewall logs at home computer (connected to BSNL via modem in bridge mode), I see that there are very frequent packects that are being blocked by Zone Alarm (mostly to ports 135 and 445). Had the modem being operating in pppoe mode, its firewall would have taken care of these and many others.So, it appears that for added security, the BSNL modems should not be used in bridge mode.The downside is that in pppoe mode, if you need to open any ports in your computer, you need to use port forwarding in the modem.
