Hello,
I agree with above comments -
Backdoor Trojans allow the remote attackers to perform various malicious activities on the compromised machine.
System Infected: Backdoor Houdini Activity
http://www.symantec.com/security_response/attacksignatures/detail.jsp?asid=27071
Take a close look at the Traffic logs, where you see these alerts...if the IP address(es) are external, there's not much you can do...the nature of the internet is to allow unsolicited attempts for communication.
If the communications are coming from external sources, you can certainly block those IP addresses at the perimeter firewall, and other things such as leveraging intrusion prevention (assuming you've got that, or it's part of the perimeter firewall).
If the attacks are coming from WITHIN your network, you'll need to do some seluthing to get to the bottom of what's actually attacking and deal with it. My gut, however, leads me to believe that your logs show external IP addresses.
Script kiddies out there are constantly running programs that will try to use exploits on machines...odds are low that you're specifically being targeted.
If the IP addresses in the logs are external to your network, the only way you can completely block the alerts is to configure your perimeter firewall to not allow incoming external traffic to this machine...which, I suspect, would completely negate the usefulness of the server itself.
Also, you can Run the SymHelp Utility to check if any suspicious files are found and if there are, submit the same to Symantec Security Response Team.
Using Symantec Help (SymHelp) Tool, how do we Collect the Suspicious Files and Submit the same to Symantec Security Response Team.
Hope that helps!!