Hello,

my question is what IPs / IP ranges is Google using?

There i see following IPs:

108.177.0.0/17
172.217.0.0/16
173.194.0.0/16
2001:4860:4000::/36
203.208.60.0/24
207.126.144.0/20
209.85.128.0/17
216.239.32.0/19
216.58.192.0/19
2404:6800:4000::/36
2607:f8b0:4000::/36
2800:3f0:4000::/36
2a00:1450:4000::/36
2c0f:fb50:4000::/36
35.192.0.0/12
64.18.0.0/20
64.233.160.0/19
64.68.80.0/21
65.52.0.0/14
66.102.0.0/20
66.249.64.0/19
72.14.192.0/18
74.125.0.0/16

Another IPs are mentioned here: https://github.com/justjavac/Google-...ster/README.md . When i parsed that file using bash script:
wget --timeout=10 --quiet https://raw.githubusercontent.com/ju...ster/README.md -O /tmp/googleipfile
grep -o '[0-9]\{1,3\}\.[0-9]\{1,3\}\.[0-9]\{1,3\}\.[0-9]\{1,3\}' /tmp/googleipfile|sort -u >> /tmp/gips
rm -f /tmp/googleipfile
The /tmp/gips then contained 4312 IPs: https://pastebin.com/S2hb775K

I could create bash script to insert them into firewall whitelist (not to be blocked):
#!/bin/bash

wget --timeout=10 --quiet https://raw.githubusercontent.com/ju...ster/README.md -O /tmp/googleipfile
grep -o '[0-9]\{1,3\}\.[0-9]\{1,3\}\.[0-9]\{1,3\}\.[0-9]\{1,3\}' /tmp/googleipfile|sort -u >> /tmp/gips

while read ip;do
ipset -exist add whitelist $ip
done < /tmp/gips
rm -f /tmp/googleipfile /tmp/gips
Before execution i would do:
ipset create whitelist maxelem 1000111222
iptables -I INPUT 1 -m set --match-set whitelist src -j ACCEPT
to create ipset list and allow its contents in firewall. Yet unsure if it is good idea because server would become vulnerable from that IPs.