Ability to check for firewalls

[meichengg]

I sometimes face with firewalls on some specific servers or IP ranges. For example, when i scan a range /22, only a few IPs behind a firewall, they detect the packets that masscan sends and shows that all 65535 ports are open, is there any way to detect or skip if which IP is actual behind a firewall like my situation? Thanks.

[meichengg]

It's really spammy when i scan for big range like /22 or /21.