http://kzaeunogz6s75ptgy6ifjzwwy75xdfenenswvrczd7mewxgrad5a.b32.i2p/blog/https-tunnels
Also, the TLS certificates used for this HTTPS tunnel have a CA and server certificate whose CN (Common Name) is a single period. Even though that's obviously not a valid domain, we thought it might be a good idea to use it anyway because DPI implementations that don't get fooled by SNI will be able to see the server's CN during this HTTPS tunnel's TLS handshake, and there's a possibility that a single period might bypass that DPI.