To reset the passwords on IPBrick (Debian) you will need to edit the default Grub menu at the boot screen.
Select the kernel and the Grub Boot screen and press e
Locate the kernel line of and enter
at the very end.
The server will then boot at drop you at the command prompt.
Enter the following to reset the passwords and reboot the server
mount -rw -o remount / mount /usr /usr/bin/passwd username
[ you will now be prompted to confirm and change the password]
shutdown -r -n now
The server will now reboot and you can login locally with the passwords you have just set.