Do I need help with iptables?

Question

iptables

I need rules on iptables
For example
, port 601, the first connected two IP address will allow access, the rest will be denied. The first 2 IP address of one can be connected to the 3 IP address instead of the 1st one. Simultaneously 2 ip address can connect port definition. This rule needs shadowsock vpn. one ss key can connect 2 ip address at the same time. I searched but they don't work. I need to limit the connected ip address to the definition of a port on the server. I found a sense to limit connections to one IP address, it also does not work normally.