Ubuntu uses a set of netfilter hooks inside the Linux kernel, allowing specific kernel modules to register callback functions with the kernel's networking stack. Those functions, usually applied to the traffic in the form of filtering and modification rules, are called for every packet that traverses the respective hook within the networking stack. The iptables commands help us with this filtering...
List Current IP Tables Rules
iptables --list-rules
Drop All Incoming (INPUT) Traffic from 182.23.0.1 to 182.23.127.254 (/17)
iptables -A INPUT -s 182.23.0.0/17 -j DROP