Network tools

Checks that connect to a target run on our server, only reach public addresses, and aren't stored.

IP subnet calculator

IPv4 / IPv6

SSL certificate check

Validity, issuer, covered names, TLS version

DNS record lookup

Compare results from mainland China and abroad

Email domain check

MX · SPF · DKIM · DMARC

HTTP header check

Redirects, headers, security headers

Open port check

Tests your current public IP from outside
Common: Web 80/443 · Remote 22/3389/5900 · Proxy ports · Games — Only your own IP can be tested. Behind carrier-grade NAT (CGNAT), port forwarding usually doesn't work.

MAC address vendor lookup

IEEE registry, detects random MACs

My request headers