Comment by kccqzy

The default of 2h is not just a Linux default; it's straight up from the RFC.

https://www.rfc-editor.org/rfc/rfc9293.html#name-tcp-keep-al...

> 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).