Hands-on 05-indexers-trackers-and-usenet-providers: Lab

name

Classify synthetic discovery and transfer services

objective

Create a local service catalog, classify each component, and generate a policy report without making any network requests.

scope_rule

Every file created, modified, or removed by this lab is under /opt/lab-classroom/class53/. The supplied evaluator uses only Python standard-library modules and does not contact external systems.

steps

step

1

instruction

Create the isolated lab and output directories.

command

mkdir -p /opt/lab-classroom/class53/output

step

2

instruction

Create a synthetic catalog. The names describe fictional lab components and are not provider recommendations.

command

cat > /opt/lab-classroom/class53/catalog.json <<'EOF'
[
{
"name": "Synthetic Usenet Catalog",
"role": "usenet_indexer",
"transport": "https",
"authentication": "api_key",
"returns": "nzb",
"authorized_content_only": true
},
{
"name": "Synthetic NNTP Access",
"role": "usenet_provider",
"transport": "nntps",
"authentication": "account_secret",
"returns": "article_bodies",
"authorized_content_only": true
},
{
"name": "Synthetic Torrent Catalog",
"role": "torrent_indexer",
"transport": "https",
"authentication": "api_key",
"returns": "torrent_metadata",
"authorized_content_only": true
},
{
"name": "Synthetic Peer Coordinator",
"role": "torrent_tracker",
"transport": "https",
"authentication": "none",
"returns": "peer_information",
"authorized_content_only": true
}
]
EOF

step

3

instruction

Create the offline evaluator. It validates allowed roles, checks transport and policy fields, and records the dependency associated with each role.

command

cat > /opt/lab-classroom/class53/evaluate.py <<'PY'
import json
from pathlib import Path

root = Path('/opt/lab-classroom/class53')
source = root / 'catalog.json'
destination = root / 'output' / 'recommendations.json'

rules = {
'usenet_indexer': {
'expected_return': 'nzb',
'dependency': 'usenet_provider and usenet_download_client',
'purpose': 'discovery'
},
'usenet_provider': {
'expected_return': 'article_bodies',
'dependency': 'usenet_download_client',
'purpose': 'transfer infrastructure'
},
'torrent_indexer': {
'expected_return': 'torrent_metadata',
'dependency': 'bittorrent_client',
'purpose': 'discovery'
},
'torrent_tracker': {
'expected_return': 'peer_information',
'dependency': 'bittorrent_client and participating peers',
'purpose': 'peer coordination'
}
}

records = json.loads(source.read_text(encoding='utf-8'))
report = []
for record in records:
role = record.get('role')
findings = []
rule = rules.get(role)
if rule is None:
findings.append('unknown role')
else:
if record.get('returns') != rule['expected_return']:
findings.append('returned artifact does not match role')
if record.get('transport') not in {'https', 'nntps'}:
findings.append('encrypted transport not declared')
if record.get('authorized_content_only') is not True:
findings.append('authorization policy not affirmed')
report.append({
'name': record.get('name'),
'role': role,
'purpose': rule['purpose'] if rule else 'unknown',
'dependency': rule['dependency'] if rule else 'manual review',
'status': 'pass' if not findings else 'review',
'findings': findings
})

destination.parent.mkdir(parents=True, exist_ok=True)
destination.write_text(json.dumps(report, indent=2) + '\n', encoding='utf-8')
print(f'Wrote {len(report)} classified records to {destination}')
PY

step

4

instruction

Run the evaluator. It reads and writes only within the class directory.

command

python3 /opt/lab-classroom/class53/evaluate.py

step

5

instruction

Inspect the generated policy report.

command

python3 -m json.tool /opt/lab-classroom/class53/output/recommendations.json

step

6

instruction

Confirm that each synthetic component passed and that discovery roles are distinct from transfer or coordination roles.

command

python3 -c "import json; from pathlib import Path; p=Path('/opt/lab-classroom/class53/output/recommendations.json'); data=json.loads(p.read_text()); assert len(data)==4; assert all(x['status']=='pass' for x in data); assert {x['purpose'] for x in data}=={'discovery','transfer infrastructure','peer coordination'}; print('Class 53 verification passed')"

extension

Make one reversible edit inside catalog.json, such as changing the synthetic tracker transport from https to http, rerun the evaluator, and observe that its status becomes review. Restore https and rerun the verification command. Do not add real service addresses or credentials.