I tried to connect Cloud SQL proxy using the following command on Ubuntu 16.04 LTS.
./cloud_sql_proxy -instances=***.**.**.***=tcp:3306 -credential_file=/var/www/auth-keys/kinre-cloudsql.json
using credential file for authentication; email=cloud-sequel-proxyauth@project.iam.gserviceaccount.com
Listening on 127.0.0.1:3306 for ***.****.***.**
Ready for new connections
After that, I lost SSH connection and Even if I try creating new instance and connecting, I'm unable to connect.
Error code is..[/usr/bin/ssh] exited with return code [255]
How to solve this problem?