Is it possible to activate TCP keepalive on Apple iOS devices

Question

Apple device === Router === WiFi module

Apple device(iPhone) is connecting to WiFi module port 2000 with TCP connection. I want to activate TCP keepalive packet send

Answer 1

see: http://en.wikipedia.org/wiki/Keepalive#TCP_keepalive

Usually, keepalive time (net.inet.tcp.keepidle) is 7200sec by default. I don't know that is true in iOS or not, but "no less than 2 hours" is clearly required by RFC 1122.

This interval MUST be configurable and MUST default to no less than two hours.

So, how could you configure it in your application? try:

#import 
#import 
#import 
#import 

int on = 1;
int delay = 120;
setsockopt(socket_handle, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on));
setsockopt(socket_handle, IPPROTO_TCP, TCP_KEEPALIVE, &delay, sizeof(delay));

see man tcp.

I confirmed this works on iOS Simulator (iPhone 5s / iOS 8.0).