3 ms·

TCP connection can be open and idle for hours without keep alives. This can easily be configured with kernel parameters: https://www.tldp.org/HOWTO/TCP-Keepali

by fyfy18 8y ago

TCP connection can be open and idle for hours without keep alives. This can easily be configured with kernel parameters: https://www.tldp.org/HOWTO/TCP-Keepalive-HOWTO/usingkeepalive.html https://www.tldp.org/HOWTO/TCP-Keepalive-HOWTO/usingkeepaliv... I suspect the hard bit for normal apps is keeping the app active on the device while it is in the background. Google has their FCM receiver running as a low level service so can make sure it is always running.

ktjfi 8y ago
You can configure it locally in your kernel, but your ISP will most likely close your connections for you, especially if you're behind a CGNAT.
- londons_explore 8y ago
  Even if you have native IPv6, some carriers do connection tracking anyway to prevent random port scans from the internet waking up your phone or trying various exploits.