PaloAlto Networks
https://urlfiltering.paloaltonetworks.com/
Fortinet
http://metal.fortiguard.com/tests/
MxToolbox
IANA
https://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.xhtml
Microsoft
https://testconnectivity.microsoft.com/
Qualys
https://www.ssllabs.com/ssltest/
Bad SSL
McAfee
https://www.trustedsource.org/
https://transparencyreport.google.com/
Heise
Jodies
Huawei Marine
https://www.submarinecablemap.com/
RIPE NCC
Common Vulnerabilities and Exposures
https://cve.mitre.org/cve/search_cve_list.html
Virustotal
https://www.virustotal.com/de/