SUDDEN "Permission denied (publickey,gssapi-keyex,gssapi-with-mic)." !!
On Google Compute Engine, my server suddenly ceased to respond "gcloud compute ssh" command 3 days ago. It only shows Permission denied (publickey,gssapi-keyex,gssapi-with-mic). After making new account, I looked into the /var/log/secure, but it only said Connection closed by xxx.xxx.xxx.xxx Changing LogLevel of /etc/ssh/sshd_config to VERBOSE doesn't make big difference. It only showed Failed publickey for [ login name ] from xxx.xxx.xxx.xxx port xxxxx ssh2 Connection closed by xxx.xxx.xxx.xxx Googling about ssh login problems, many blogs tell to doubt permissions of ssh files and directories, such as ~/.ssh and ~/.ssh/authorized_keys, but they seemed to have proper permissions. Now, I just found the home directory(~/) also has to have permission 700. It's embarrassing I do not remember how the permission changed in the first place, but I hope this will help somebody from spending three very useless days. Conclusion, when you suddenly cannot connect to