It's unfit for general use and abuses the DNS protocol to stealthily convey data, hence the shadiness. You're right, it needn't be used in a negative way. DNS t

It's unfit for general use and abuses the DNS protocol to stealthily convey data, hence the shadiness. You're right, it needn't be used in a negative way. DNS tunneling is slow, needs polling for incoming traffic (due to the way dns works over udp) and is usually used to circumvent firewalls for both good (censorship) and bad reasons (exfiltrating data).