At the "set up your firewall" stage of the installer, chose to start from the high-security firewall (lets through DNS & DHPC). Go to Custom, and also let in SSH. When install is done, notice that DNS doesn't work "service ipchains status" prints out the firewall rules: "please let ssh in, otherwise deny" From the way the GUI appears (when I chose custom, my "high-medium-none" choise was not greyed-out), I assumed that I was modifying the rules, instead of defining them.
*** This bug has been marked as a duplicate of 25951 ***