Level 15: TLS, Not Plaintext

Same setup as the last level, but this time the service has upgraded. It's now speaking TLS. If you try to use plain nc, it'll just hang or error out because the server is expecting an encrypted handshake that nc doesn't know how to do.

You need a tool that understands SSL/TLS. openssl s_client is the way to go.

A pro tip here: use the -quiet flag. Without it, OpenSSL dumps a mountain of certificate data onto your screen before it actually lets you talk to the service. With it, the output is clean and direct.

openssl s_client -quiet -connect 127.0.0.1:30001
# Input: REDACTED

Once the encrypted tunnel is established, the service greets you, you send the password, and you get the next one.

Result: REDACTED

TL;DR: nc is for plaintext; openssl s_client is for encrypted (TLS) services.