If they are on the same l2 network then your options are basically either to use nginx ACLs or a local firewall on the nginx host since the traffic wont traverse the firewall.
Something like iptables -IINPUT -s 1.2.3.0/24 -j DROP on the nginx host should work
If they are on the same l2 network then your options are basically either to use nginx ACLs or a local firewall on the nginx host since the traffic wont traverse the firewall.
Something like
iptables -I INPUT -s 1.2.3.0/24 -j DROPon the nginx host should work