Change DNS for mobile data without using an app (My phone is rooted and runs Android 5.1)

How can one change the DNS addresses of mobile data (and persistently, if possible) without the requirement of an app?
I did not find a way to reliably do it without an app.

I often use OpenDNS Family Shield, but sometimes it blocks me to visit some particular hacking site and then I need to quickly and easily change the DNS servers.

I used to use Set DNS but it stopped to work in Android 4.3 and further, so I created Override DNS, a new app which mimics Set DNS' behaviour, but it's updated to work even in Lollipop. It has some other nice feature like a PIN protection ad a Wi-Fi SSID filter, too.

The only way I can see to do it without an app is something like an iptables rule to redirect any traffic going to udp/53 to some other ip. A similar procedure is shown in a XDA thread.

I paste here the iptables rules for completeness (I did not tested them)

$IPTABLES -t nat -D OUTPUT -p tcp --dport 53 -j DNAT --to-destination 208.67.222.222:53 || true
$IPTABLES -t nat -D OUTPUT -p udp --dport 53 -j DNAT --to-destination 208.67.222.222:53 || true
$IPTABLES -t nat -I OUTPUT -p tcp --dport 53 -j DNAT --to-destination 208.67.222.222:53
$IPTABLES -t nat -I OUTPUT -p udp --dport 53 -j DNAT --to-destination 208.67.222.222:53


Everything directed from the Android device to any IP, port UDP and TCP 53 is redirected to 208.67.222.222 which is one of OpenDNS' DNS server.

These commands should be placed in a script which is run at every device boot. That functionality depends on your specific ROM. I don't know if something similar can be done in a stock ROM without using an app. Override DNS solves this problem, too.