Hello everyone, I'm having a tough problem with Smart Security 4, it's firewall component to be precise, and the NX NoMachine Windows client. Can't say exactly which day it happend, but roughly two month ago Smart Security 4 started blocking NX NoMachine whenever I try to connect to a Linux computer across my LAN. It used to work perfectly for almost two years, but it just stopped one day. I'm having the same issue with my Laptop, so it's definitely Smart Security. The initial connection (encrypted) always goes through port 22 (SSH), afterwards it also uses a port between 5000-5200 if the rest of the traffic is unencrypted, otherwise it just uses port 22. The interesting thing is: If the firewall is disabled, it connects just fine. Enabling the firewall after the NX client has successfull connected doesn't break it either. It just keeps working fine. Obviously I don't want to disable the firewall everytime I need to connect to the Linux computer, which is why I'm trying to find a solution. The firewall runs in interactive mode (always has), all components of NX NoMachine have been granted full access to LAN and Internet. I'm running Windows 7 Professional x64. All other programms work just fine. So the big question: What is the firewall doing during the connection phase? All required ports are open, there are no log entries or anything. No popup, no warning, no nothing - it just doesn't work. Any suggestions/help would be most welcome! EDIT: Just added two wireshark pcap files.