sudo iptables -F
sudo iptables -A INPUT -p tcp -s 109.123.74.85 --dport 27000 -j ACCEPT
sudo iptables -A INPUT -p tcp -s 188.170.80.4 --dport 27000 -j ACCEPT
sudo iptables -A INPUT -p tcp  --dport 27000 -j REJECT
sudo iptables -L

$ sudo iptables -L
Chain INPUT (policy ACCEPT)
target     prot opt source               destination
ACCEPT     tcp  --  109.123.74.85        anywhere             tcp dpt:27000
ACCEPT     tcp  --  188.170.80.4         anywhere             tcp dpt:27000
REJECT     tcp  --  anywhere             anywhere             tcp dpt:27000 reject-with icmp-port-unreachable

Chain FORWARD (policy ACCEPT)
target     prot opt source               destination

Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination

Chain DOCKER (0 references)
target     prot opt source               destination

Chain DOCKER-ISOLATION (0 references)
target     prot opt source               destination

python3 -m http.server 27000