android adb - daemon still not runningerror: cannot connect to daemon

For people getting:

* daemon not running. starting it now on port 5037 *
* daemon started successfully *
** daemon still not runningerror: cannot connect to daemon

Check your iptables!
if you are whitelisting INPUT on local interface, you'll get this error. You need to allow at least port 5037 through on lo.

Or if you're happy with allowing all input on lo:

sudo iptables -I INPUT -i lo -j ACCEPT

hope that saves you the hour I just wasted :-)