sslscan: add page (#7451)

pages/common/sslscan.md

@@ -0,0 +1,16 @@
+# sslscan
+
+> Check SSL/TLS protocols and ciphers supported by a server.
+> More information: <https://github.com/rbsec/sslscan>.
+
+- Test a server on port 443:
+
+`sslscan {{example.com}}`
+
+- Test a specified port:
+
+`sslscan {{example.com}}:{{465}}`
+
+- Show certificate information:
+
+`testssl --show-certificate {{example.com}}`