I'm new to ispconfig 3 and just followed the perfect server tutorial to setup my ispconfig. However, after a weekend, only two days, my VPS server's outgoing network traffic increased dramatically 150GB, and ALL the services are OFFLINE, but DNS service. I thought this big traffic is caused by email, so have already stopped postfix. But problems remain. Does anyone have any ideas? Thanks!
Check your server with rkhunter. Then check with: netstat -tap which services are listening to which posts.