WEB2 RECON PIPELINE

Full asset discovery from nothing to a prioritized URL list ready for hunting.

SETUP (one-time)

# 1. Set your Chaos API key (get free key at chaos.projectdiscovery.io)
export CHAOS_API_KEY="your-key-here"
# Add to ~/.zshrc or ~/.bashrc for persistence:
echo 'export CHAOS_API_KEY="your-key-here"' >> ~/.zshrc

# 2. Update nuclei templates (run weekly)
nuclei -update-templates

# 3. Configure subfinder with API keys for more sources
mkdir -p ~/.config/subfinder
cat > ~/.config/subfinder/config.yaml << 'EOF'
# Get free keys at: virustotal.com, securitytrails.com, censys.io, shodan.io
virustotal: [YOUR_VT_KEY]
securitytrails: [YOUR_ST_KEY]
censys_apiid: YOUR_CENSYS_ID
censys_secret: YOUR_CENSYS_SECRET
shodan: [YOUR_SHODAN_KEY]
EOF

# 4. Verify all tools installed
which subfinder httpx dnsx nuclei katana waybackurls gau dalfox ffuf anew gf interactsh-client

THE 5-MINUTE RULE

If a target shows nothing interesting after 5 minutes of recon, move on. Don't burn hours on dead surface.

5-minute kill signals:

• All subdomains return 403 or static marketing pages
• No API endpoints visible in URLs
• No JavaScript bundles with interesting endpoint paths
• nuclei returns 0 medium/high findings
• No forms, no authentication, no user data

STANDARD RECON PIPELINE

Pre-Hunt: Always Run First

TARGET="target.com"

# Step 0: Passive — crt.sh certificate transparency (no API key needed)
curl -s "https://crt.sh/?q=%.${TARGET}&output=json" \
  | jq -r '.[].name_value' \
  | sed 's/\*\.//g' \
  | sort -u > /tmp/subs.txt
echo "[+] crt.sh: $(wc -l < /tmp/subs.txt) subdomains"

# Step 1: Chaos API (ProjectDiscovery — most comprehensive source)
curl -s "https://dns.projectdiscovery.io/dns/$TARGET/subdomains" \
  -H "Authorization: $CHAOS_API_KEY" \
  | jq -r '.[]' >> /tmp/subs.txt

echo "[+] Chaos returned $(wc -l < /tmp/subs.txt) subdomains"

# Step 2: subfinder (passive multi-source)
subfinder -d $TARGET -silent | anew /tmp/subs.txt
assetfinder --subs-only $TARGET | anew /tmp/subs.txt

echo "[+] Total subdomains after all sources: $(wc -l < /tmp/subs.txt)"

# Step 3: DNS resolution + live host check
cat /tmp/subs.txt | dnsx -silent | httpx -silent -status-code -title -tech-detect | tee /tmp/live.txt

echo "[+] Live hosts: $(wc -l < /tmp/live.txt)"

# Step 4: URL crawl
cat /tmp/live.txt | awk '{print $1}' | katana -d 3 -jc -kf all -silent | anew /tmp/urls.txt

# Step 5: Historical URLs
echo $TARGET | waybackurls | anew /tmp/urls.txt
gau $TARGET --subs | anew /tmp/urls.txt

echo "[+] Total URLs: $(wc -l < /tmp/urls.txt)"

# Step 6: Nuclei scan
nuclei -l /tmp/live.txt -t ~/nuclei-templates/ -severity critical,high,medium -o /tmp/nuclei.txt

Output to Organized Directory

TARGET="target.com"
RECON_DIR="recon/$TARGET"
mkdir -p $RECON_DIR

# All outputs go here:
/tmp/subs.txt         → $RECON_DIR/subdomains.txt
/tmp/live.txt         → $RECON_DIR/live-hosts.txt
/tmp/urls.txt         → $RECON_DIR/urls.txt
/tmp/nuclei.txt       → $RECON_DIR/nuclei.txt

ATTACK SURFACE TRIAGE

Find Interesting Targets in URL List

# Parameters worth testing
cat /tmp/urls.txt | grep -E "[?&](id|user|file|path|url|redirect|next|src|token|key|api_key)=" | tee /tmp/interesting-params.txt

# API endpoints
cat /tmp/urls.txt | grep -E "/api/|/v1/|/v2/|/v3/|/graphql|/rest/|/gql" | tee /tmp/api-endpoints.txt

# File upload endpoints
cat /tmp/urls.txt | grep -E "upload|file|attachment|document|image|avatar|photo|media" | tee /tmp/uploads.txt

# Admin/internal paths
cat /tmp/urls.txt | grep -E "/admin|/internal|/debug|/test|/staging|/dev|/management|/console" | tee /tmp/admin-paths.txt

# Authentication endpoints
cat /tmp/urls.txt | grep -E "/oauth|/login|/auth|/sso|/saml|/oidc|/callback|/token" | tee /tmp/auth-paths.txt

gf Patterns (Quick Classification)

# Install gf patterns: https://github.com/tomnomnom/gf
cat /tmp/urls.txt | gf xss | tee /tmp/xss-candidates.txt
cat /tmp/urls.txt | gf ssrf | tee /tmp/ssrf-candidates.txt
cat /tmp/urls.txt | gf idor | tee /tmp/idor-candidates.txt
cat /tmp/urls.txt | gf sqli | tee /tmp/sqli-candidates.txt
cat /tmp/urls.txt | gf redirect | tee /tmp/redirect-candidates.txt
cat /tmp/urls.txt | gf lfi | tee /tmp/lfi-candidates.txt
cat /tmp/urls.txt | gf rce | tee /tmp/rce-candidates.txt

JS ANALYSIS

SecretFinder (API keys, tokens in JS bundles)

# Activate venv
source ~/tools/SecretFinder/.venv/bin/activate

# Scan a single JS file
python3 ~/tools/SecretFinder/SecretFinder.py -i "https://target.com/static/js/main.js" -o cli

# Scan all JS URLs found in recon
cat /tmp/urls.txt | grep "\.js$" | head -50 | while read url; do
  echo "=== $url ==="
  python3 ~/tools/SecretFinder/SecretFinder.py -i "$url" -o cli 2>/dev/null
done

deactivate

LinkFinder (Endpoints hidden in JS)

source ~/tools/LinkFinder/.venv/bin/activate

# Single JS file
python3 ~/tools/LinkFinder/linkfinder.py -i "https://target.com/app.js" -o cli

# All pages (crawls JS from HTML)
python3 ~/tools/LinkFinder/linkfinder.py -i "https://target.com" -d -o cli

deactivate

DIRECTORY FUZZING

ffuf — Standard Fuzzing

# Directory discovery on a live host
ffuf -u "https://target.com/FUZZ" \
     -w ~/wordlists/common.txt \
     -mc 200,201,204,301,302,307,401,403 \
     -ac \
     -t 40 \
     -o /tmp/ffuf-dirs.json

# API endpoint discovery
ffuf -u "https://target.com/api/FUZZ" \
     -w ~/wordlists/api-endpoints.txt \
     -mc 200,201,204,301,302 \
     -ac \
     -t 20

# IDOR fuzzing with authenticated request
# Create req.txt with Authorization: Bearer TOKEN
ffuf -request /tmp/req.txt \
     -request-proto https \
     -w <(seq 1 10000) \
     -fc 404 \
     -ac \
     -t 10

TARGET SCORING — GO / NO-GO

Score before spending time. Skip if score < 4.

< 4: Skip 4-5: Only if nothing better available 6-8: Good — spend 1-3 days >= 9: Excellent — spend up to 1 week

Pre-Dive Hard Kill Signals

1. Max bounty < $500 → not worth your time
2. All recent reports are N/A or duplicate → hunters saturated it
3. Scope is only a static marketing page → no attack surface
4. Company < 5 employees with no revenue → won't pay
5. Explicitly excludes your planned bug class in rules

TECH STACK DETECTION (2 min)

# Response headers reveal backend
curl -sI https://target.com | grep -iE "server|x-powered-by|x-aspnet|x-runtime|x-generator"

# Common signals:
# Server: nginx + X-Powered-By: PHP/7.4 → PHP backend
# Server: gunicorn OR X-Powered-By: Express → Python/Node.js
# X-Powered-By: ASP.NET → .NET
# Server: Apache Tomcat → Java
# X-Runtime: Ruby → Ruby on Rails

# Framework from JS bundle paths:
# /_next/static/ → Next.js
# /static/js/main.chunk.js → CRA (React)
# /packs/ → Ruby on Rails + Webpacker
# /__nuxt/ → Nuxt.js (Vue)

Stack → Primary Bug Class Map

CONTINUOUS MONITORING SETUP

Set up once per target. Alerts you before other hunters.

New Subdomain Alerts (daily cron)

#!/bin/bash
TARGET="target.com"
KNOWN="/tmp/$TARGET-subs-known.txt"

subfinder -d $TARGET -silent > /tmp/$TARGET-subs-fresh.txt
curl -s "https://dns.projectdiscovery.io/dns/$TARGET/subdomains" \
  -H "Authorization: $CHAOS_API_KEY" \
  | jq -r '.[]' >> /tmp/$TARGET-subs-fresh.txt

# Diff against known
NEW=$(comm -23 <(sort /tmp/$TARGET-subs-fresh.txt) <(sort $KNOWN 2>/dev/null))

if [ -n "$NEW" ]; then
  echo "NEW SUBDOMAINS: $NEW"
  echo "$NEW" >> $KNOWN
fi

# Schedule: crontab -e → 0 8 * * * /bin/bash ~/monitors/subs-watch.sh

GitHub Commit Watch

#!/bin/bash
REPO="TargetOrg/target-app"
LAST_SHA="/tmp/$REPO-last-sha.txt"

CURRENT=$(curl -s "https://api.github.com/repos/$REPO/commits?per_page=1" | jq -r '.[0].sha')
KNOWN=$(cat $LAST_SHA 2>/dev/null)

if [ "$CURRENT" != "$KNOWN" ]; then
  echo "New commit on $REPO: $CURRENT"
  echo $CURRENT > $LAST_SHA
  # Get changed files
  curl -s "https://api.github.com/repos/$REPO/commits/$CURRENT" \
    | jq -r '.files[].filename' | grep -E "auth|middleware|route|permission|role|admin"
fi

# Schedule: */30 * * * * /bin/bash ~/monitors/github-watch.sh

PORT SCANNING (often skipped — don't skip)

# naabu — fast port scanner from ProjectDiscovery
# Finds non-standard ports: 8080, 8443, 3000, 8888, 9000, etc.
cat /tmp/live.txt | awk '{print $1}' | naabu -port 80,443,8080,8443,3000,4000,5000,8000,8888,9000,9090,9200,6379 -silent | tee /tmp/open-ports.txt

# Why this matters: admin panels, debug services, internal APIs often run on alt ports
# Example wins: :8080/actuator/env (Spring Boot), :9200/_cat/indices (Elasticsearch), :6379 (Redis)

SECRET SCANNING IN JS BUNDLES

# trufflehog — high-signal secret detection with entropy analysis
# Scans JS files and git repos
pip install trufflehog3 2>/dev/null || true
trufflehog filesystem --only-verified recon/$TARGET/ 2>/dev/null

# SecretFinder — manual JS bundle scan (already in tools/)
source ~/tools/SecretFinder/.venv/bin/activate
cat /tmp/urls.txt | grep "\.js$" | head -100 | while read url; do
  python3 ~/tools/SecretFinder/SecretFinder.py -i "$url" -o cli 2>/dev/null
done
deactivate

# Quick grep for common patterns in downloaded JS
wget -q -r -l 1 -A "*.js" -P /tmp/js-files/ "https://$TARGET" 2>/dev/null
grep -rn "api_key\|apiKey\|client_secret\|access_token\|private_key\|AWS_SECRET\|AKIA" /tmp/js-files/ 2>/dev/null

GITHUB DORKING FOR TARGET

# Search GitHub for hardcoded secrets before hunting the app
TARGET_ORG="TargetOrgName"  # Check their GitHub org

# Useful dorks (search on github.com):
# org:TARGET_ORG password
# org:TARGET_ORG api_key
# org:TARGET_ORG "Authorization: Bearer"
# org:TARGET_ORG .env
# org:TARGET_ORG "BEGIN RSA PRIVATE KEY"

# CLI with gh (GitHub CLI):
gh search code "api_key" --owner "$TARGET_ORG" --json path,repository 2>/dev/null | jq '.'
gh search code "password" --owner "$TARGET_ORG" --json path,repository 2>/dev/null | head -20

# GitDorker (if installed):
python3 ~/tools/GitDorker/GitDorker.py -t GITHUB_TOKEN -d ~/tools/GitDorker/Dorks/alldorksv3 -q "$TARGET" -org

30-MINUTE RECON PROTOCOL

Minutes 0-5: Read Program Page

Note:
- ALL in-scope assets (every domain listed)
- Out-of-scope list (read carefully — common trap)
- Safe harbor statement
- Impact types accepted (some exclude "low")
- Average bounty amount (signals program generosity)

Minutes 5-15: Asset Discovery

Run the standard pipeline above. Focus on live.txt output.

Minutes 15-25: Surface Map

Run gf patterns and the interesting-params grep above.

Minutes 25-30: Manual Exploration

Open Burp Suite. Browse the app with proxy on:

1. Register an account
2. Perform main user actions (create/read/update/delete resources)
3. Note all API calls in Burp history
4. Look for endpoints not in your URL list

After 30 min: Prioritize

Priority 1: API endpoints with ID parameters → IDOR candidates
Priority 2: File upload features → XSS/RCE candidates
Priority 3: OAuth/SSO flows → auth bypass candidates
Priority 4: Search/filter with user input → SQLi/SSRF/SSTI candidates
Priority 5: Admin/debug endpoints → auth bypass candidates

Toolchain fallback (when dnsx / httpx crash)

The projectdiscovery Go binaries (dnsx, httpx, naabu) occasionally SIGSEGV on macOS arm64 due to a cgo / system-resolver interaction. The crash signature is identical regardless of install method — both brew install and go install github.com/projectdiscovery/<tool>@latest produce binaries that segfault at the same address. Smoke-test once before relying on them in a real engagement:

dnsx -version   # if SIGSEGV: use the dig fallback below
httpx -version  # if SIGSEGV: use the curl fallback below

dnsx → dig fallback

# Replaces: dnsx -l subs.txt -a -resp -silent
while read s; do
  ips=$(dig +short +tries=1 +time=3 "$s" \
    | grep -E '^[0-9.]+$' \
    | paste -sd, -)
  [ -n "$ips" ] && echo "$s|$ips"
done < subs.txt

httpx → curl fallback

# Replaces: httpx -l subs.txt -silent -status-code -title -tech-detect
while read s; do
  resp=$(curl -s -L -m 5 -o /tmp/body \
    -w "%{http_code}|%{url_effective}|%{header_server}" \
    "https://$s")
  code=$(echo "$resp" | cut -d'|' -f1)
  if [ "$code" != "000" ]; then
    title=$(grep -oE '<title[^>]*>[^<]*</title>' /tmp/body | head -1 | sed 's/<[^>]*>//g')
    echo "$s|$resp|$title"
  fi
done < subs.txt

Trade-off: Serial vs. concurrent. The fallback handles ~24 subdomains in 14 seconds; the same workload on httpx with default 50 threads finishes in 2-3 seconds. For VDP-scale recon (< 100 subdomains) the fallback is fine. For mass recon (1000+) fix the toolchain first.

Verified against HackerOne's own VDP in docs/verification/recon-hackerone-vdp.md.

API Spec / Swagger / OpenAPI Discovery (2024-2026 surface)

API spec endpoints are the single highest-leverage recon target on any modern .NET / Node / Python / Java backend. The spec discloses every endpoint, HTTP methods, parameter names + types + formats, models, validation rules — a complete attack-map in JSON. Default routes are commonly left enabled in production. Add this wordlist to the directory-fuzzing phase (after the standard common.txt pass).

Default discovery path wordlist (paste into swagger-paths.txt)

# NSwag / Swashbuckle (ASP.NET Core)
/swagger
/swagger/
/swagger/index.html
/swagger/ui/index.html
/swagger/v1/swagger.json
/swagger/v2/swagger.json
/swagger/v3/swagger.json
/swagger/docs/v1
/swagger/docs/v2
/swagger-ui
/swagger-ui/
/swagger-ui.html
/swagger-resources
/swagger-resources/configuration/ui
/nswag
/nswag/index.html
/api/swagger
/api/swagger.json
/api/swagger/v1/swagger.json
/api/openapi
/api/openapi.json
/api/v1/swagger.json
/api/v2/swagger.json
/api-docs
/api-docs/swagger.json

# OpenAPI generic
/openapi
/openapi.json
/openapi.yaml
/openapi.yml
/openapi/v1.json
/openapi/v2.json
/openapi/v3.json
/.well-known/openapi.json

# Java / Spring (Springfox / springdoc)
/v2/api-docs
/v3/api-docs
/v3/api-docs.yaml
/v3/api-docs/swagger-config
/swagger-ui/index.html

# Python (FastAPI / Flask-RESTPlus / Connexion / DRF)
/docs
/docs/
/redoc
/redoc/
/openapi.json
/swagger.json
/swagger/?format=openapi
/swagger.yaml

# Express / Node / Hapi
/api-docs
/api-docs.json
/swagger.json
/swagger-stats
/graphql-docs

# GraphQL adjacent (often co-located)
/graphql
/graphiql
/playground
/altair
/voyager
/graphql/console
/graphql-explorer

# ReDoc / RapiDoc / Stoplight / alt UIs
/redoc
/redoc.html
/redoc-ui.html
/rapidoc
/rapidoc.html
/stoplight
/elements

# Misc / dev-leftover
/actuator
/actuator/openapi
/actuator/mappings
/q/openapi
/q/swagger-ui
/docs/swagger.json
/api/v1/docs
/api/v2/docs
/internal/swagger
/admin/swagger
/management/swagger

Integration with the standard pipeline

# After live-hosts.txt is built (Phase 1 / 2), run:
ffuf -w swagger-paths.txt -u "https://FUZZ.target.com" -mc 200,302 -fs 0 -t 50 -o swagger-hits.json
# Or with httpx for content-aware filtering:
httpx -l live-hosts.txt -path swagger-paths.txt -mc 200 -mr "swagger|openapi" -json | tee swagger-hits.jsonl
# For every hit:
jq '.paths | keys' swagger.json > endpoints.txt
jq '.components.schemas' swagger.json > schemas.json   # mass-assignment field candidates

Why this matters for recon-to-hunting handoff

• Spec → mass IDOR/BOLA — jq '.paths | keys' swagger.json becomes the input list for Autorize/ffuf per-user testing.
• Spec → mass-assignment payload construction — components.schemas.UserUpdateDto enumerates isAdmin, emailVerified, tenantId, role.
• Spec → hidden endpoint discovery — /internal/*, /debug/*, /v0/*, /legacy/* routes documented but never auth-gated.
• Spec → injection-class seeding — every parameter's type + format + enum + max-length means payloads pass validation before reaching the sink. Especially valuable against ASP.NET Core where the model binder rejects malformed input before any controller logic.

Tools

• kiterunner — natively ingests OpenAPI spec, generates requests against the API.
• sj (Swagger Jacker) — purpose-built for Swagger spec exploitation.
• apidetector (brinhosa) — Swagger-UI mass scanner.
• XSSwagger (vavkamil) — detects vulnerable Swagger UI versions (CVE-2018-25031 family).
• nuclei -t http/exposures/apis/ — built-in templates for default spec paths.

Anti-pattern reminder

A 404/403 on /swagger does NOT mean no spec is exposed. Many .NET projects route the spec under /api/swagger/v1/swagger.json rather than /swagger. Always test the full path list, not just the root.

Full attack-chain analysis is in hunt-api-misconfig → NSwag / Swagger / OpenAPI Spec Exposure.

Related Skills & Chains

• offensive-osint — When recon needs concrete probes / wordlists / regexes beyond the basic pipeline. Workflow primitive: this skill produces the URL set; offensive-osint provides the secret regexes, GraphQL/Swagger paths, and identity-fabric probes you apply to that URL set.
• osint-methodology — When you need a severity rubric for what you discovered. Workflow primitive: after recon outputs subdomains.txt / live-hosts.txt / urls.txt, score each asset against osint-methodology's findings rubric to decide what gets a finding versus what stays in the asset graph.
• hunt-subdomain — When recon surfaces stale CNAMEs / dangling DNS. Workflow primitive: any subdomain in subdomains.txt whose CNAME points to S3 / GitHub Pages / Heroku / Shopify / Azure should auto-route to hunt-subdomain for takeover validation.
• security-arsenal — When the URL set is classified by gf and ready for active testing. Workflow primitive: gf xss/ssrf/sqli/idor output names become payload-class queries against security-arsenal's payload library.
• bb-methodology — When recon completes and Phase 1 transitions to Phase 2 (Mapping). Workflow primitive: hand the live host + URL set back to bb-methodology Phase 2 for endpoint mapping and Phase 3 vulnerability discovery routing.

Operator Notes (Claude-BugHunter)

Engagement-derived + 2026-specific additions to the vendored foundation. Wisdom from real authorized engagements + Phase 2 verification across this repo's 31+ skill-area live tests. The upstream pipeline covers the WHAT; this layer covers the WHEN-IT-WORKS-vs-WHEN-IT-DOESN'T.

Cross-TLD pivot discipline

Phase 2C's HackerOne VDP recon walked from hackerone.com (24 subdomains) into a sister TLD hacker.one (12 more subdomains found in JS bundle references). Operators who only enumerate *.target.com miss attack surface that the target legitimately operates on a different domain.

Always grep JS bundles for plausible sibling TLDs:

# pull all JS, grep for sibling-TLD candidates
for url in $(cat live-hosts.txt); do
  curl -s "$url" | grep -oE 'src="[^"]+\.js"' | sed 's/src="//;s/"//'
done | sort -u > js-urls.txt

# then on each JS file
for j in $(cat js-urls.txt); do
  curl -s "$j" | grep -oE '[a-z0-9.-]+\.(io|app|one|dev|test|cloud|ai|co)' | sort -u
done | sort -u > sibling-tld-candidates.txt

Common sibling-TLD patterns: target.com → target.io / target.app / target.one / target.dev / target.test / target-corp.com / target-cdn.net. Always validate via WHOIS or by checking if the cert chain trusts the same internal CA before treating the sister TLD as in-scope.

Subdomain wordlist priorities by 2026

Top discovery prefixes by hit rate against enterprise VDPs in our 2024-2026 corpus:

mta-sts.*          api.*              docs.*
dev-*              staging-*          *-qa
*-stage            *-uat              events.*
portal.*           customer.*         partner.*
vendor.*           internal-*         admin-*
employee-*         hr.*               jobs.*
sso.*              auth.*             id.*

Internal-looking subdomains often expose more surface than the marketing site — partner.target.com and vendor-portal.target.com frequently have weaker auth than the main app because they're scoped for "trusted" external users. Always send a probe to the long-tail wordlist after the standard subfinder run completes.

Live-host probe: how to fingerprint stack quickly

curl -sI <host> headers are 80% of the fingerprint:

• Server: — apache / nginx / cloudflare / kestrel (= .NET Core) / openresty / envoy
• X-Powered-By: — PHP version, ASP.NET version, Express.js
• X-Drupal-Cache, X-Generator: Drupal 9 — Drupal
• X-Generator: WordPress — WordPress
• Via: — CDN chain (1.1 varnish, 1.1 cloudfront)
• Set-Cookie: names — JSESSIONID (Java), PHPSESSID (PHP), ASP.NET_SessionId (.NET), connect.sid (Express), laravel_session (Laravel)

JS bundle filename patterns:

• /_next/static/ = Next.js
• /_nuxt/ = Nuxt
• /assets/static/ with hash filenames = Vite
• /static/js/main.*.chunk.js = Create React App
• runtime.*.js + polyfills.*.js + main.*.js = Angular CLI

The first 10s of recon should yield a stack guess; the rest is targeting. If your fingerprint contradicts itself (Server says nginx, Set-Cookie says ASP.NET) you've found a reverse proxy front-end — note the origin app for later smuggling/cache attacks.

GitHub Pages 404 vs takeover signal

Critical distinction operators get wrong:

• "Page not found · GitHub Pages" with HTTP 404 means the repo EXISTS — NOT a takeover.
• "There isn't a GitHub Pages site here" means the repo was deleted — TAKEOVER candidate.

Same distinction for CloudFront:

• "Error - 404" with Server: CloudFront = distribution exists, origin returned 404 — NOT a takeover.
• "The request could not be satisfied" with X-Cache: Error from cloudfront = origin missing entirely — potential takeover.

Phase 2C verified both patterns live. Always check the EXACT response body string before filing a takeover finding — the takeover-scanner tools (subzy, subjack) match on multiple fingerprints and frequently false-positive on the "still owned, just empty" case.

Toolchain fallback

Already covered in this file's Phase 2C addition. Quick reminder: dnsx/httpx may segfault on macOS arm64; the dig+curl fallback works for < 100-host runs in ~14 seconds. Don't burn an hour debugging Go binary panics when the fallback gets you to the same URL set.