Not, sfaik, without rebuilding the f/w. Not very important if the HG612 is only providing an ethernet bridge. Which is how it is configured and shipped by BT. But if the Huawei is re-configured by the end-user to run pppd on the device itself then it's very important to have an appropriate firewall rule chain. With rules to deny or drop WAN-side connection attempts to telnetd (and sshd, etc).
Talking of passwords, the f/w for the 2701 has a very good (and bizarre) one to secure it. Perfect for warding off the evil spirits out there. And evil smells, too!
EDIT: Just to add, the 2701 is ostensibly very secure since sshd although included in the f/w is disabled by default.
cheers, a
