I have launched a Debian system using AMI 05f3ef71 in Amazon EC2, but I have no lock connecting to it using SSH as suggested in "Connecting to Your Linux/UNIX Instances Using SSH". I tried several user names: ec2-user, root, debian... None of them worked. I always get a Permission denied (publickey) error message. Using ec2-get-console-output instance_id as suggested doesn't work either, it requires option "-K". If I supply it, I get the error message Required option '-C, --cert CERT' missing, but I have no idea what to supply there. Port 22 is opened on the affected instance. Does anyone have an idea what I could try to log in to my instance?