After installing the agent on a computer, the status of an agent is grey and appears the "Cannot establish connection with the KServer" but the port 5721 is opened from firewall, can anyone knows the answers?
You could potentially try telnetting to your kserver ip on port 5721 - if it connects then you know that's not the problem. It will probably fail..
Have you checked that windows firewall isn't blocking it, that there isn't a local security program blocking it?
If you have an advanced firewall, you could try enabling logging for port 5721 and then restart the agent on the local machine... also have a look for the agentmon log on the local machine as that should give you some useful info..
Best of luck,
While firewalls can certainly get in the way of an agent being able to communicate with the kserver, I would also take a look at the check-in control settings on the server and agent. The check-in control settings on the server for the agents are located under Agent->Check-In Control function. The Agent side check-in control settings are accessible via the Set Account context sensitive menu item when you right-click on the Agent icon on the machine that cannot communicate. The agent must be able to resolve any NetBIOS or DNS Fully Qualified Domain Name (FQDN) in the check-in control setting to the IP address on the kserver which is listening on port 5721. If the agents IP packets cannot reach the kserver, because there is no route to the kservers IP address, or there are blocked ports on firewalls, or there is no NetBIOS or DNS name resolution working on that agent that can properly resolve the name of the kservers to the IP address on which the kserver is listening on port 5721, then the agent icon will remain grey and the agent will not be able to check-in. So use some command line utilities on the agent machine to check 1) name resolution (nslookup), 2) IP routing from the agent to the kserver (tracert), and 3) access to the TCP port 5721 of the kserver (portqry), to see what is failing and hopefully that will reveal where issue resides.
Kaseya Professional Services
+1 what *he* said ;)