We have a scenario where we cannot connect to our stunnel server running on port 443 on our network, which only allows access to Internet via a proxy server. On the contrary, when we tried a SSL VPN using Adito, we could connect to the HTTPS site and setup a SSL tunnel to our remote server.
Stunnel and SSL VPN were running on different hosts outside the restricted network. As for the symptoms of the stunnel failing, we simply got a
"Connect failed" with stunnel, but no attempt was made to capture the raw traffic. But with Adito, the connection was smooth and works like a charm.
My questions, is how do connections to a stunnel differ from SSL-VPN, if both are running on the same port 443, and both use SSL to encrypt data?