ja4-platform/shared/clickhouse/12_thesis_features.sql

-- =============================================================================
-- 12_thesis_features.sql — Techniques avancées de détection (Thèse §5)
--
-- Implémente les techniques originales décrites dans :
--   docs/THESIS_HTTP_Traffic_Detection.md
--
-- Chaque section crée une table d'agrégation + MV + vue analytique.
-- Les features calculées sont exposées dans view_thesis_features_1h,
-- joinable avec view_ai_features_1h sur (window_start, src_ip, ja4, host).
-- =============================================================================


-- =============================================================================
-- §5.1 — Entropie de séquence de chemins (Path Sequence Entropy)
--
-- Principe : stocker les séquences ordonnées de chemins par session et calculer
-- l'entropie de transition de Markov d'ordre 1 sur les chemins normalisés à
-- profondeur 2 (ex: /shop/product/*).
--
-- Signal :
--   - Humain : entropie élevée (transitions variées, non-déterministes)
--   - Crawler : entropie faible (transitions prévisibles, séquentielles)
--   - Scanner : entropie nulle (même chemin répété)
-- =============================================================================

CREATE TABLE IF NOT EXISTS ja4_processing.agg_path_sequences_1h
(
    window_start   DateTime,
    src_ip         IPv6,
    ja4            LowCardinality(String),
    host           LowCardinality(String),
    -- Séquences (unix_timestamp, path) — triées par timestamp à la lecture
    path_sequence  AggregateFunction(groupArray(100), Tuple(UInt32, String))
)
ENGINE = AggregatingMergeTree()
PARTITION BY toDate(window_start)
ORDER BY (window_start, src_ip, ja4, host)
TTL window_start + INTERVAL 7 DAY
SETTINGS ttl_only_drop_parts = 1;


DROP VIEW IF EXISTS ja4_processing.mv_agg_path_sequences_1h;

CREATE MATERIALIZED VIEW ja4_processing.mv_agg_path_sequences_1h
TO ja4_processing.agg_path_sequences_1h AS
SELECT
    toStartOfHour(time) AS window_start,
    toIPv6(src_ip)      AS src_ip,
    ja4,
    host,
    groupArrayState(100)(
        tuple(toUInt32(toUnixTimestamp(time)), path)
    ) AS path_sequence
FROM ja4_logs.http_logs
GROUP BY window_start, src_ip, ja4, host;


-- =============================================================================
-- §5.3 — Fingerprinting par timing inter-requêtes (Request Cadence Fingerprint)
--
-- Principe : stocker les timestamps nanoseconde de chaque requête et calculer
-- le coefficient de variation (CV) des intervalles inter-requêtes, ainsi que
-- le ratio burst/pause.
--
-- Signal :
--   - Humain : CV ≈ 1.5–3.0 (intervalles irréguliers)
--   - Bot régulier : CV ≈ 0.01–0.3 (sleep-based, quasi-constant)
--   - Bot avec jitter : CV ≈ 0.3–0.8 (aléatoire mais borné)
-- =============================================================================

CREATE TABLE IF NOT EXISTS ja4_processing.agg_request_timing_1h
(
    window_start    DateTime,
    src_ip          IPv6,
    ja4             LowCardinality(String),
    host            LowCardinality(String),
    -- Timestamps nanoseconde (a_timestamp de mod_reqin_log)
    request_times   AggregateFunction(groupArrayIf(500), UInt64, UInt8)
)
ENGINE = AggregatingMergeTree()
PARTITION BY toDate(window_start)
ORDER BY (window_start, src_ip, ja4, host)
TTL window_start + INTERVAL 7 DAY
SETTINGS ttl_only_drop_parts = 1;


DROP VIEW IF EXISTS ja4_processing.mv_agg_request_timing_1h;

CREATE MATERIALIZED VIEW ja4_processing.mv_agg_request_timing_1h
TO ja4_processing.agg_request_timing_1h AS
SELECT
    toStartOfHour(time) AS window_start,
    toIPv6(src_ip)      AS src_ip,
    ja4,
    host,
    -- a_timestamp = nanoseconde depuis epoch (mod_reqin_log)
    -- Filtre les orphelins B-only (a_timestamp = 0)
    groupArrayIfState(500)(a_timestamp, a_timestamp > 0) AS request_times
FROM ja4_logs.http_logs
GROUP BY window_start, src_ip, ja4, host;


-- =============================================================================
-- §5.5 — Dérive de fingerprint TLS intra-session (Intra-Session JA4 Drift)
-- §5.8 — Empreinte comportementale cross-domaine (Cross-Domain Session Linking)
--
-- Ces deux techniques nécessitent une agrégation par (window, src_ip) sans
-- décomposition par ja4/host.
--   §5.5 : séquence temporelle de JA4 par IP → drift_ratio
--   §5.8 : distribution des hits par host → host_diversity, sweep_speed,
--          coverage_uniformity
-- =============================================================================

CREATE TABLE IF NOT EXISTS ja4_processing.agg_ip_behavior_1h
(
    window_start   DateTime,
    src_ip         IPv6,
    -- §5.5 : séquences (unix_timestamp, ja4) pour détection de drift
    ja4_sequence   AggregateFunction(groupArray(200), Tuple(UInt32, String)),
    -- §5.8 : distribution des hits par host (sumMap agrège par clé)
    host_hits_keys AggregateFunction(sumMap, Array(String), Array(UInt64)),
    -- §5.8 : nombre de hosts distincts
    host_count     AggregateFunction(uniq, String),
    -- §5.8 : métriques temporelles
    total_hits     SimpleAggregateFunction(sum, UInt64),
    first_seen     SimpleAggregateFunction(min, DateTime),
    last_seen      SimpleAggregateFunction(max, DateTime)
)
ENGINE = AggregatingMergeTree()
PARTITION BY toDate(window_start)
ORDER BY (window_start, src_ip)
TTL window_start + INTERVAL 7 DAY
SETTINGS ttl_only_drop_parts = 1;


DROP VIEW IF EXISTS ja4_processing.mv_agg_ip_behavior_1h;

CREATE MATERIALIZED VIEW ja4_processing.mv_agg_ip_behavior_1h
TO ja4_processing.agg_ip_behavior_1h AS
SELECT
    toStartOfHour(time) AS window_start,
    toIPv6(src_ip)      AS src_ip,
    groupArrayState(200)(
        tuple(toUInt32(toUnixTimestamp(time)), ja4)
    ) AS ja4_sequence,
    sumMapState([toString(host)], [toUInt64(1)]) AS host_hits_keys,
    uniqState(toString(host)) AS host_count,
    count() AS total_hits,
    min(time) AS first_seen,
    max(time) AS last_seen
FROM ja4_logs.http_logs
GROUP BY window_start, src_ip;


-- =============================================================================
-- §5.4 — Détection de navigation synthétique (Resource Dependency Tree)
--
-- Principe : stocker les tuples (timestamp, is_asset) par session pour
-- mesurer le délai HTML→premier asset et la simultanéité des assets.
--
-- Signal :
--   - Navigateur réel : cascade naturelle (50–200ms HTML→CSS→JS)
--   - Playwright : chargement quasi-simultané (<10ms)
--   - Scraper avec assets : séquentiel sans cascade hiérarchique
-- =============================================================================

CREATE TABLE IF NOT EXISTS ja4_processing.agg_resource_cascade_1h
(
    window_start     DateTime,
    src_ip           IPv6,
    ja4              LowCardinality(String),
    host             LowCardinality(String),
    -- Tuples (unix_timestamp, is_asset) pour analyse de cascade
    resource_loads   AggregateFunction(groupArray(200), Tuple(UInt32, UInt8))
)
ENGINE = AggregatingMergeTree()
PARTITION BY toDate(window_start)
ORDER BY (window_start, src_ip, ja4, host)
TTL window_start + INTERVAL 7 DAY
SETTINGS ttl_only_drop_parts = 1;


DROP VIEW IF EXISTS ja4_processing.mv_agg_resource_cascade_1h;

CREATE MATERIALIZED VIEW ja4_processing.mv_agg_resource_cascade_1h
TO ja4_processing.agg_resource_cascade_1h AS
SELECT
    toStartOfHour(time) AS window_start,
    toIPv6(src_ip)      AS src_ip,
    ja4,
    host,
    groupArrayState(200)(
        tuple(
            toUInt32(toUnixTimestamp(time)),
            -- Classification : 1 = asset statique, 0 = document/API
            toUInt8(match(path, '(?i)\\.(css|js|png|jpg|jpeg|gif|svg|ico|woff2?|ttf|eot|webp|avif)$'))
        )
    ) AS resource_loads
FROM ja4_logs.http_logs
GROUP BY window_start, src_ip, ja4, host;


-- =============================================================================
-- §5.4 — Vue resource_cascade (Resource Dependency Tree)
--
-- Calcule le délai moyen entre le premier document et le premier asset,
-- et l'écart-type des timestamps des assets (simultanéité).
-- Doit être créée AVANT view_thesis_features_1h qui la référence.
-- =============================================================================

CREATE OR REPLACE VIEW ja4_processing.view_resource_cascade_1h AS
WITH
cascade_raw AS (
    SELECT
        window_start, src_ip, ja4, host,
        arraySort(x -> x.1, groupArrayMerge(200)(resource_loads)) AS sorted_loads
    FROM ja4_processing.agg_resource_cascade_1h
    WHERE window_start >= now() - INTERVAL 24 HOUR
    GROUP BY window_start, src_ip, ja4, host
    HAVING length(sorted_loads) >= 3
),
cascade_split AS (
    SELECT
        window_start, src_ip, ja4, host,
        -- Timestamps des documents (is_asset = 0)
        arrayFilter(x -> x.2 = 0, sorted_loads) AS docs,
        -- Timestamps des assets (is_asset = 1)
        arrayFilter(x -> x.2 = 1, sorted_loads) AS assets
    FROM cascade_raw
)
SELECT
    window_start, src_ip, ja4, host,
    length(docs) AS doc_count,
    length(assets) AS asset_count,
    -- Délai moyen premier document → premier asset (secondes)
    -- Navigateur réel : 0.05–0.2s ; Playwright : <0.01s ; Scraper : >1s ou 0
    if(
        length(docs) > 0 AND length(assets) > 0,
        toFloat64(assets[1].1 - docs[1].1),
        -1.0
    ) AS root_to_first_asset_delay,
    -- Simultanéité des assets : écart-type des timestamps des assets
    -- Navigateur : faible (batch parallèle) ; Scraper : élevé (séquentiel)
    if(
        length(assets) >= 2,
        sqrt(arrayReduce('varPop',
            arrayMap(x -> toFloat64(x.1), assets)
        )),
        -1.0
    ) AS asset_load_stddev
FROM cascade_split
WHERE length(docs) > 0 OR length(assets) > 0;


-- =============================================================================
-- view_thesis_features_1h — Vue unifiée des features avancées
--
-- Joint les 4 tables d'agrégation ci-dessus pour exposer toutes les features
-- de la thèse §5 dans une seule vue, joinable avec view_ai_features_1h.
-- =============================================================================

CREATE OR REPLACE VIEW ja4_processing.view_thesis_features_1h AS
WITH
-- ── §5.1 : Extraire et trier les séquences de chemins ────────────────────────
path_raw AS (
    SELECT
        window_start, src_ip, ja4, host,
        groupArrayMerge(100)(path_sequence) AS raw_tuples
    FROM ja4_processing.agg_path_sequences_1h
    WHERE window_start >= now() - INTERVAL 24 HOUR
    GROUP BY window_start, src_ip, ja4, host
),
path_entropy AS (
    SELECT
        window_start, src_ip, ja4, host,
        -- Normaliser les chemins à profondeur 2 (/shop/product/123 → /shop/product)
        arrayMap(
            t -> concat('/', arrayStringConcat(
                arraySlice(splitByChar('/', t.2), 2, 2), '/'
            )),
            arraySort(x -> x.1, raw_tuples)
        ) AS norm_paths,
        length(raw_tuples) AS request_count
    FROM path_raw
),
path_bigrams AS (
    SELECT
        window_start, src_ip, ja4, host,
        request_count,
        arrayMap(
            (a, b) -> concat(a, '->', b),
            arraySlice(norm_paths, 1, length(norm_paths) - 1),
            arraySlice(norm_paths, 2)
        ) AS bigrams
    FROM path_entropy
    WHERE request_count >= 3
),
path_features AS (
    SELECT
        window_start, src_ip, ja4, host,
        request_count AS path_request_count,
        -- Entropie de Shannon normalisée [0, 1] des transitions de chemins
        if(
            length(arrayDistinct(bigrams)) > 1,
            -arrayReduce('sum', arrayMap(
                bg -> (toFloat64(arrayCount(x -> x = bg, bigrams)) / toFloat64(length(bigrams)))
                    * log2(toFloat64(arrayCount(x -> x = bg, bigrams)) / toFloat64(length(bigrams))),
                arrayDistinct(bigrams)
            )) / log2(toFloat64(length(arrayDistinct(bigrams)))),
            0.0
        ) AS path_transition_entropy
    FROM path_bigrams
),

-- ── §5.3 : Cadence inter-requêtes ───────────────────────────────────────────
timing_raw AS (
    SELECT
        window_start, src_ip, ja4, host,
        arraySort(groupArrayIfMerge(500)(request_times)) AS sorted_times
    FROM ja4_processing.agg_request_timing_1h
    WHERE window_start >= now() - INTERVAL 24 HOUR
    GROUP BY window_start, src_ip, ja4, host
),
timing_deltas AS (
    SELECT
        window_start, src_ip, ja4, host,
        -- Intervalles en millisecondes entre requêtes consécutives
        arrayMap(
            (a, b) -> toFloat64(b - a) / 1000000.0,
            arraySlice(sorted_times, 1, length(sorted_times) - 1),
            arraySlice(sorted_times, 2)
        ) AS deltas_ms
    FROM timing_raw
    WHERE length(sorted_times) >= 3
),
cadence_features AS (
    SELECT
        window_start, src_ip, ja4, host,
        length(deltas_ms) + 1 AS cadence_request_count,
        -- Coefficient de variation : σ/μ (humain ≈ 1.5–3.0 ; bot ≈ 0.01–0.3)
        if(
            arrayReduce('avg', deltas_ms) > 0,
            sqrt(arrayReduce('varPop', deltas_ms))
                / arrayReduce('avg', deltas_ms),
            0.0
        ) AS cadence_cv,
        -- Ratio burst/pause : fraction de Δt < 100ms (burst) vs Δt > 5000ms (pause)
        if(
            length(deltas_ms) > 0,
            toFloat64(arrayCount(x -> x < 100.0, deltas_ms))
                / toFloat64(length(deltas_ms)),
            0.0
        ) AS burst_ratio,
        if(
            length(deltas_ms) > 0,
            toFloat64(arrayCount(x -> x > 5000.0, deltas_ms))
                / toFloat64(length(deltas_ms)),
            0.0
        ) AS pause_ratio,
        -- Autocorrélation lag-1 : ρ₁(Δt) — humain ≈ 0 (indépendant), bot avec jitter ≈ 0.8+
        if(
            length(deltas_ms) >= 4 AND arrayReduce('varPop', deltas_ms) > 1e-9,
            (
                arrayReduce('avg',
                    arrayMap(
                        (a, b) -> (a - arrayReduce('avg', deltas_ms)) * (b - arrayReduce('avg', deltas_ms)),
                        arraySlice(deltas_ms, 1, length(deltas_ms) - 1),
                        arraySlice(deltas_ms, 2)
                    )
                ) / arrayReduce('varPop', deltas_ms)
            ),
            0.0
        ) AS lag1_autocorrelation,
        -- Loi de Benford : χ² entre premiers chiffres des Δt et distribution attendue
        -- Benford P(d) = log10(1 + 1/d) pour d=1..9
        if(
            length(deltas_ms) >= 10,
            arraySum(
                arrayMap(
                    d -> pow(
                        (toFloat64(arrayCount(
                            x -> x = d,
                            arrayMap(v -> toUInt8(substring(toString(toUInt64(greatest(abs(v), 1))), 1, 1)), deltas_ms)
                        )) / toFloat64(length(deltas_ms)))
                        - [0.301, 0.176, 0.125, 0.097, 0.079, 0.067, 0.058, 0.051, 0.046][d],
                        2
                    ) / [0.301, 0.176, 0.125, 0.097, 0.079, 0.067, 0.058, 0.051, 0.046][d],
                    [1, 2, 3, 4, 5, 6, 7, 8, 9]
                )
            ),
            0.0
        ) AS benford_deviation
    FROM timing_deltas
),

-- ── §5.5 : Dérive JA4 intra-session ────────────────────────────────────────
drift_raw AS (
    SELECT
        window_start, src_ip,
        groupArrayMerge(200)(ja4_sequence) AS raw_ja4_tuples,
        uniqMerge(host_count) AS n_hosts,
        sum(total_hits) AS ip_total_hits,
        min(first_seen) AS ip_first_seen,
        max(last_seen) AS ip_last_seen,
        sumMapMerge(host_hits_keys) AS host_hits_merged
    FROM ja4_processing.agg_ip_behavior_1h
    WHERE window_start >= now() - INTERVAL 24 HOUR
    GROUP BY window_start, src_ip
),
drift_segments AS (
    SELECT
        window_start, src_ip,
        n_hosts, ip_total_hits, ip_first_seen, ip_last_seen,
        host_hits_merged,
        -- Extraire la séquence de JA4 triée par temps
        arrayMap(t -> t.2, arraySort(x -> x.1, raw_ja4_tuples)) AS ja4_seq,
        -- Segmenter en fenêtres de 10 minutes : identifier le JA4 dominant par segment
        -- Simplification : compter les transitions JA4 consécutives
        length(raw_ja4_tuples) AS seq_len
    FROM drift_raw
),
ja4_drift_features AS (
    SELECT
        window_start, src_ip,
        n_hosts, ip_total_hits, ip_first_seen, ip_last_seen,
        host_hits_merged,
        -- Drift ratio = transitions consécutives / (len - 1)
        -- Transition = ja4_seq[i] != ja4_seq[i-1]
        if(
            length(ja4_seq) > 1,
            toFloat64(arrayCount(
                (a, b) -> a != b,
                arraySlice(ja4_seq, 1, length(ja4_seq) - 1),
                arraySlice(ja4_seq, 2)
            )) / toFloat64(length(ja4_seq) - 1),
            0.0
        ) AS ja4_drift_ratio,
        length(arrayDistinct(ja4_seq)) AS ja4_distinct_in_session
    FROM drift_segments
    WHERE seq_len >= 2
),

-- ── §5.8 : Cross-Domain Session Linking ──────────────────────────────────────
cross_domain_features AS (
    SELECT
        window_start, src_ip,
        ja4_drift_ratio,
        ja4_distinct_in_session,
        -- Host diversity : nombre de hosts distincts visités
        n_hosts AS host_diversity,
        -- Host sweep speed : hosts / durée en secondes
        if(
            dateDiff('second', ip_first_seen, ip_last_seen) > 0,
            toFloat64(n_hosts) / toFloat64(dateDiff('second', ip_first_seen, ip_last_seen)),
            0.0
        ) AS host_sweep_speed,
        -- Host coverage uniformity : 1 - σ(hits_per_host) / μ(hits_per_host)
        -- Valeur proche de 1 = distribution uniforme (scanner)
        -- Valeur proche de 0 = concentré sur 1-2 hosts (humain)
        if(
            length(host_hits_merged.2) > 1
                AND arrayReduce('avg', arrayMap(x -> toFloat64(x), host_hits_merged.2)) > 0,
            1.0 - least(1.0,
                sqrt(arrayReduce('varPop', arrayMap(x -> toFloat64(x), host_hits_merged.2)))
                / arrayReduce('avg', arrayMap(x -> toFloat64(x), host_hits_merged.2))
            ),
            0.0
        ) AS host_coverage_uniformity
    FROM ja4_drift_features
),

-- ── §5.8b : Similarité Jaccard cross-domaine ────────────────────────────────
-- Principe : un scanner visite les mêmes chemins (/admin, /wp-login.php, /.env)
-- sur plusieurs hosts distincts. Le coefficient de Jaccard mesure la proportion
-- de chemins partagés entre hosts.
-- Signal élevé (>0.5) = même liste de chemins sur plusieurs sites → scanning systématique.
jaccard_paths AS (
    SELECT
        toStartOfHour(time)  AS window_start,
        toIPv6(src_ip)       AS src_ip,
        -- Fraction de chemins normalisés apparaissant sur ≥2 hosts distincts
        toFloat64(countIf(distinct_hosts >= 2)) / greatest(toFloat64(count()), 1.0)
            AS cross_domain_path_similarity
    FROM (
        SELECT
            toStartOfHour(time) AS time,
            src_ip,
            -- Normaliser le chemin à profondeur 2 (ignorer les paramètres de query)
            arrayStringConcat(
                arraySlice(
                    splitByChar('/', replaceRegexpAll(path, '\\?.*', '')),
                    1, 3
                ),
                '/'
            ) AS path_norm,
            uniqExact(host) AS distinct_hosts
        FROM ja4_logs.http_logs
        WHERE time >= now() - INTERVAL 24 HOUR
        GROUP BY time, src_ip, path_norm
        HAVING distinct_hosts >= 1
    )
    GROUP BY window_start, src_ip
)

-- ── Jointure finale : features §5.1/§5.3 par (window, ip, ja4, host)
--    enrichies des features §5.5/§5.8 par (window, ip)
--    et des features §5.4 Resource Cascade par (window, ip, ja4, host)
SELECT
    p.window_start,
    p.src_ip,
    p.ja4,
    p.host,
    -- §5.1 Path Sequence Entropy
    p.path_transition_entropy,
    p.path_request_count,
    -- §5.3 Request Cadence Fingerprint
    c.cadence_cv,
    c.burst_ratio,
    c.pause_ratio,
    c.lag1_autocorrelation,
    c.benford_deviation,
    c.cadence_request_count,
    -- §5.4 Resource Dependency Tree
    coalesce(rc.doc_count, 0) AS doc_count,
    coalesce(rc.asset_count, 0) AS asset_count,
    coalesce(rc.root_to_first_asset_delay, -1.0) AS root_to_first_asset_delay,
    coalesce(rc.asset_load_stddev, -1.0) AS asset_load_stddev,
    -- §5.5 Intra-Session JA4 Drift
    d.ja4_drift_ratio,
    d.ja4_distinct_in_session,
    -- §5.8 Cross-Domain Session Linking
    d.host_diversity,
    d.host_sweep_speed,
    d.host_coverage_uniformity,
    -- §5.8b Jaccard cross-domaine (proportion de chemins partagés entre hosts)
    coalesce(jp.cross_domain_path_similarity, 0.0) AS cross_domain_path_similarity
FROM path_features p
LEFT JOIN cadence_features c
    ON p.window_start = c.window_start
    AND p.src_ip = c.src_ip
    AND p.ja4 = c.ja4
    AND p.host = c.host
LEFT JOIN cross_domain_features d
    ON p.window_start = d.window_start
    AND p.src_ip = d.src_ip
LEFT JOIN jaccard_paths jp
    ON p.window_start = jp.window_start
    AND p.src_ip = jp.src_ip
LEFT JOIN ja4_processing.view_resource_cascade_1h rc
    ON p.window_start = rc.window_start
    AND p.src_ip = rc.src_ip
    AND p.ja4 = rc.ja4
    AND p.host = rc.host;


-- =============================================================================
-- §5.2 — Graphe bipartite JA4×ASN (Bipartite Bot Fleet Detection)
--
-- IMPOSSIBLE EN MV PURE : nécessite un algorithme de détection de communautés
-- (Louvain / Label Propagation) sur un graphe bipartite, ce qui dépasse les
-- capacités du SQL analytique.
--
-- PLAN D'IMPLÉMENTATION FUTURE (Python) :
--   1. Requête : SELECT ja4, toString(src_asn), count(DISTINCT src_ip) AS edge_weight
--      FROM ja4_processing.agg_host_ip_ja4_1h
--      WHERE window_start >= now() - INTERVAL 24 HOUR
--      GROUP BY ja4, src_asn HAVING edge_weight >= 3
--   2. Construction du graphe bipartite G = (JA4 ∪ ASN, E) avec networkx
--   3. Projection sur les JA4 : G_ja4 = bipartite.weighted_projected_graph(G, ja4_nodes)
--   4. Détection de communautés : communities = community.louvain_communities(G_ja4)
--   5. Pour chaque communauté :
--      fleet_score = len(community) * nx.density(G.subgraph(community)) / log(n_asn + 1)
--   6. Écriture dans une table ja4_processing.fleet_detection_results
--
-- Dépendances : networkx >= 3.0, python-louvain
-- =============================================================================


-- =============================================================================
-- §5.6 — Corrélation DNS passive (DNS Shadow Analysis)
--
-- IMPOSSIBLE ACTUELLEMENT : ja4sentinel ne capture pas les paquets DNS (UDP/53).
--
-- PLAN D'IMPLÉMENTATION FUTURE :
--   1. Étendre ja4sentinel (capture.go) :
--      - Ajouter un BPF filter pour UDP port 53
--      - Parser les réponses DNS (paquet → query_name, response_ip, ttl)
--      - Émettre un nouveau type d'événement : dns_event
--   2. Nouvelle table ClickHouse : ja4_logs.dns_logs (time, src_ip, query_name,
--      response_ip, dns_ttl, query_type)
--   3. MV d'agrégation : agg_dns_http_correlation_1h
--      - Jointure dns_logs × http_logs par (src_ip, host ≈ query_name)
--      - Feature : dns_shadow_ratio = count(http) / nullif(count(dns), 0)
--   4. Ajout à view_thesis_features_1h
--
-- Effort estimé : modification de ja4sentinel (Go) + nouveau pipeline de corrélation
-- =============================================================================


-- =============================================================================
-- §5.7 — Invariant de ratio de compression (Compression Ratio Invariant)
--
-- IMPOSSIBLE ACTUELLEMENT : mod_reqin_log ne capture pas les tailles de réponse
-- pré/post-compression.
--
-- PLAN D'IMPLÉMENTATION FUTURE :
--   1. Étendre mod_reqin_log (mod_reqin_log.c) :
--      - Capturer r->bytes_sent (taille compressée envoyée)
--      - Capturer la taille non-compressée via output filter ou r->clength
--      - Ajouter response_bytes_compressed, response_bytes_raw au JSON
--   2. Propager dans http_logs : 2 nouvelles colonnes UInt32
--   3. Features calculables :
--      - compression_ratio = response_bytes_compressed / response_bytes_raw
--      - compression_ratio_variance = varPop(compression_ratio) par session
--      - Un bot qui ne décompresse pas = ratio constant indépendant du contenu
--   4. Ajout à l'agrégation existante ou nouvelle table
--
-- Effort estimé : modification C de mod_reqin_log + extension du schéma
-- =============================================================================