Problem stopping DNS mirror attack with Firewall

I am a relatively new MikroTik user but have some experience with firewalls. I have been having some trouble with our new internet connection going down and realize if I turned off the router, things were fine. Looking at torch I see massive amounts of UDP connections from random internet IPs to my static IP on port 53. I went into the DNS settings and turned off “Allow Remote Requests” but to no avail. So I ran these commands (with my LAN /24 insted of the x’s):

/ip firewall address-list
add address=x.x.x.x/24 list=support
/ip firewall filter
add chain=input comment=“Full access to SUPPORT address list” src-address-list=support
add action=drop chain=input comment=“Drop anything else!”

But I still see the connections in torch. So then I added this to the top of my filters:

/ip firewall filter
add action=drop chain=input dst-port=53 protocol=udp

And see the counter going up, but still see these connections. Any ideas as to what I should do and why by basic 2 line firewall isn’t stopping them? I don’t have a need for a DNS server that is accessible from the outside so completely blocking it is OK with me.

Thanks!

Here is how we solve that problem. First, you have to make exceptions for the valid DNS requests (both ways). Then you have to identify the rest of the DNS traffic and block all of it. If you are still having trouble with it, call us at 1-855-MikroTik and we can help you with that.