Below are the list of SharePoint Online firewall ports:
The only ports required are HTTP/S on 80 & 443.
The URL’s required for internet filtering (proxies) are:
*.streaming.mediaservices.windows.net
ajax.aspnetcdn.com – Office Video
r3.res.outlook.com – Office Video and Delve
Spoprod-a.akamaihd.net – Office Video and OneDrive for Business
*.onenote.com
cdn.onenote.net
crl.microsoft.com
evsecure-ocsp.verisign.com
evsecure-aia.verisign.com
evsecure-crl.verisign.com
sa.symcb.com
sd.symcb.com
*.omniroot.com
*.verisign.com
*.symcb.com
*.symcd.com
*.verisign.net
*.geotrust.com
*.entrust.net
*.public-trust.com
Finally the following is the IP address range for Sharepoint Online for IPV4 and IPV6 can be found here – https://support.office.com/en-us/article/Office-365-URLs-and-IP-address-ranges-8548a211-3fe7-47cb-abb1-355ea5aa88a2?ui=en-US&rs=en-US&ad=US#BKMK_SPO
