To be fair, the linux defaults of 2h are not working in most enterprise or cloud environments. One frequently encounter load balancers, firewalls and other proxies that drop connections after around 5-15 minutes. 15 seconds sounds very aggressive though.
> Keep-alive packets MUST only be sent when no sent data is outstanding, and no data or acknowledgment packets have been received for the connection within an interval (MUST-26). This interval MUST be configurable (MUST-27) and MUST default to no less than two hours (MUST-28).
