I'm using a linode virtual server. My machine is Ubuntu 10.04.
I got a ticket from Linode that they detected malicous activity coming from my server.
"We have detected your system with an IP of, , scanning a client we monitor. This was not a short attack but a prolonged scan and/or probe that was designed to find and intrude into the target network."
Now I'm hosting on linode to test an application, I have no idea how to manage and secure a server.
Please can someone give me some lead on how i should investigate the issue and how to solve it.