Discovered a vulnerability in ZeroShell makes it possible to carry out attacks DNS Amplification.
DNS server ZeroShell initially configured to accept recursive queries from any IP.
The attacker sends a recursive query to the short DNS server with spoofed source IP, the answer is much larger in size are sent to the address of the victim. With a massive attack heavily loaded outbound channel.
The solution – a ban recursive queries from external IP.
Add to the NETWORK -> DNS -> Options parameter: