This topic is only applicable to the grid version of Symphony.
You need to open up a few ports (vemkd, Session Director, session manager) in the firewall for the client to interact with the grid. The client first communicates with the vemkd and gets the port information of the Session Director. The client then connects to the Session Director and gets the port information of the session manager and then connects to the session manager. It is important to set appropriate port ranges for session managers because there may be multiple session managers in a Symphony grid.
In addition to port configuration, it may be necessary to configure TCP Keep Alive parameters for the connection endpoints in the Symphony environment. The Keep Alive messages are sent through the firewall periodically in order to prevent the firewall from dropping the connection during periods of no user-activity. For the Keep Alive feature to work under realistic conditions, it must be configured to start sending the messages before a routing device's idle time out is triggered. For example, if a firewall is configured to discard idle connections after 15 minutes, you would want your Keep Alive messages to be sent after 10 minutes of inactivity. For more information about TCP Keep Alive configuration, refer to Configuration of TCP connections
Symphony offers firewall support to prevent the connection between vemkd on the management host and PEM on the compute hosts from being disconnected by a firewall when the connection remains idle for long periods of time. The same firewall support is also available for the connection between the SSM on the management host and the SIMs on the compute hosts. Firewall support is enabled by configuring the EGO_ENABLE_CHAN_KEEPALIVE parameter.
The feature works by periodically passing TCP Keep-Alive Messages between the management hosts and compute hosts. The interval timing for sending the TCP keep-alive packet while the connection between the management hosts and compute hosts is idle is configurable using the EGO_CHAN_KEEPALIVE_TIME (for connection between vemkd and PEM) and PLATCOMMDRV_TCP_KEEPALIVE_TIME (for connection between SSM and SIM).