How to restrict connected devices via Wi-Fi to Mikrotik?

Question

network hardware

There is a room. There is a Mikrotik to which 30Mb / s comes.
It is necessary to distribute 50-100 Chinese who will connect via Wi-Fi from tablet phones.
Despite the fact that everyone is charged for the Internet.
How to make sure that they do not install a router and do not resell the Internet?
Kill the speed, what else can you do?

Answer 1

Many routers reduce TTL (not always and not all), so as an option to block packets with ttl=127 and 63,

/ip firewall filter
add chain=forward in-interface=local ttl=equal:127 action=drop
add chain=forward in-interface=local ttl=equal:63 action=drop

but it's not 100%. The Chinese can buy a Mikrotik or put a router with *wrt and fix ttl back :)

Answer 2

They paid for the Internet. Let them do what they want. Bandwidth restrictions will be enough to make no sense in reselling.
In addition to the method voiced by paxlo , you can also control the presence of a router / NATm manually or by passing HTTP traffic to a certain control server. If different versions of browsers are connected from the same IP, we can assume the presence of NAT. Probably, there are other options for tracking by traffic.