Linux firewall network address

What is the syntax to use to block an IP address as a network.
I’m getting hammered by 138.163.xx.yy and want to block the whole network.

Do I use or is there a different specification for specifying a network versus an address?

If you’d like to use iptables to block a host, you can use something like:

iptables -I INPUT -s 138.163.xx.yy -j DROP

for a single IP, or for an entire network, you can use:

iptables -I INPUT -s -j DROP

I was wanting to use the Linux Firewall interface in VM.
So should I specify the address of and port 80 to block this broken caching proxy server installed at the Naval Information Center?

Yeah, that should work just fine.