Accessing your Drupal website after banning your own IP

Warning: This solution was derived by guessing, not by reading manuals. But it worked for me. It also assumes some familiarity with SQL.

in short: Connect to your drupal DB and edit the `access` table.

The command I used was:

mysql> insert into access values (0, "172.16.17.18", "host", 1);
Query OK, 1 row affected (0.00 sec)

where "172.16.17.18" was the IP in the "Sorry, 172.16.17.18 has been banned" message.