For proper operation of the product, and depending on which features you want to use, various ports must be opened so that the clients and agent on remote desktops can communicate with each other. Understanding View Communications ProtocolsView components exchange messages by using several different protocols. Firewall Rules for Horizon AgentThe Horizon Agent installation program opens certain TCP ports on the firewall. Ports are incoming unless otherwise noted. TCP and UDP Ports Used by Clients and AgentsView Agent (for Horizon 6), Horizon Agent (for Horizon 7), and Horizon Client use TCP and UDP ports for network access between each other and various View server components.