The existence of a proxy can be detected by examining a timing differential between handshake messages received at a server used to establish a channel according to a first protocol and the handshake messages used to establish a secondary channel on top of the first protocol (e.g., a secure communications channel). If the time between two handshakes received at the server to set up the secondary channel is greater than the time between two handshakes received at the server to establish the initial channel, the presence of a proxy can be detected.