All ports in my system are blocked. I had did that with an third party security application. I had done this before but now I had removed the application and still my ports are blocked. That is a quiet good news for me as my system is much safer from external threats. Now I had installed Microsoft Security Essentials which is also blocked for updates. When I run the update it gave me a error message and shuts down. I am not sure what the message says but that is definitely related to some port thing. I need some help to figure out how this thing entirely work. What is the role of firewall in this and which port should keep open for Microsoft Security Essential. Does this port will only be used by it or there is a risk of keeping a port open. What is the best thing I do here to ensure the maximum security of my system. I already have a antivirus tool but I just want to add this one also for malware thing. I think my antivirus is not scanning the system properly as I found some suspicious folders.