EXERCISE 2 — Listing local suites and auditing a real server
=============================================================

PART A — what suites does YOUR openssl support for ECDHE + AES-GCM:
  openssl ciphers -v 'ECDHE+AESGCM'

  Example output (columns: name, protocol, Kx, Au, Enc, Mac):
    ECDHE-ECDSA-AES256-GCM-SHA384 TLSv1.2 Kx=ECDH Au=ECDSA Enc=AESGCM(256) Mac=AEAD
    ECDHE-RSA-AES256-GCM-SHA384   TLSv1.2 Kx=ECDH Au=RSA   Enc=AESGCM(256) Mac=AEAD
    ECDHE-ECDSA-AES128-GCM-SHA256 TLSv1.2 Kx=ECDH Au=ECDSA Enc=AESGCM(128) Mac=AEAD
    ECDHE-RSA-AES128-GCM-SHA256   TLSv1.2 Kx=ECDH Au=RSA   Enc=AESGCM(128) Mac=AEAD

  - Kx=ECDH (ephemeral here) = forward secrecy; Mac=AEAD = GCM's built-in
    integrity. The filter 'ECDHE+AESGCM' selected exactly the modern-safe
    combos. (Try also: openssl ciphers -v 'DEFAULT' to see the full set,
    or '!aNULL:!eNULL:!RC4:!3DES' style exclusions.)

PART B — audit a real server:
  nmap --script ssl-enum-ciphers -p 443 example.com

  Read the output for:
  1. PROTOCOL VERSIONS offered — look for which "TLSvX.Y:" sections appear.
     GOOD: only TLSv1.2 and TLSv1.3 sections.
     BAD:  any "TLSv1.0:" or "TLSv1.1:" section present (deprecated 2021),
           or SSLv3 (totally broken).
  2. CIPHER GRADES — each suite shows a trailing letter grade A/B/C/.../F.
     GOOD: every cipher graded A, and "least strength: A".
     BAD:  any C or F, e.g. a CBC-mode, 3DES, RC4, or RSA-kex suite.
  3. WEAK SUITES to flag if present:
     - names with _CBC_  (CBC mode -> padding-oracle risk)
     - RC4, 3DES, DES, EXPORT, NULL, anonymous (no Au) suites
     - TLS_RSA_WITH_...  (RSA key transport -> no forward secrecy)

WHAT A CLEAN RESULT LOOKS LIKE:
  - Sections only for TLSv1.2 and TLSv1.3.
  - All ECDHE_* (or 1.3 TLS_AES_/TLS_CHACHA20_) GCM/ChaCha suites.
  - "least strength: A".
  No TLS 1.0/1.1, no CBC/RC4/3DES, no RSA-kex => correctly configured.