How is the filter of IP Range calculated in the allow-backend-egress-to-vpc-fwr firewall rule at min 15:22 of Chapter 4 video Custom-Mode VPCs – Challenge Lab Solution – Firewall Rules?
I was looking to do something like that in my solution, but ended up just adding one by one the external IP address of my vms whenever it was necessary.
1 Answers
Hi Rodrigo,
IP Range depends upon the CIDR block representation. In the video, filter is applied on IP Range: 192.168.0.0/16, this means within the network, all machines which have IP range from 192.168.0.0 to 192.168.255.555 (192.168.0.0, 192.168.0.1 …. 192.168.255.254, 192.168.255.255) will filtered. There are a total of 65536 IP addresses (2 power 16).
Here is the small online utility which will help you list the range of Ip address (First IP to Last IP) for a given IP CIDR Block
https://www.ipaddressguide.com/cidr
https://mxtoolbox.com/subnetcalculator.aspx
Hope this helps!
in addition, i would highly recommend https://www.davidc.net/sites/default/subnets/subnets.html