Add remote IP into white list using iptables.

Using an iptables command:

iptables -I INPUT -s X.X.X.X/32 -j ACCEPT

So, this webapp must run with root privilege.

1. Block any incoming NEW connect:

    iptables -A INPUT -t tcp -m state --state NEW -j REJECT
   

2. Allow localhost connect:

    iptables -I INPUT -s 127.0.0.1/32 -j ACCEPT
   

3. Allow web visit from any IP:

    iptables -I INPUT -t tcp --dport 8080 -j ACCEPT