Linux SELinux cache or propagation drift response

When this happens

Use this when the panel says fixed but some users still see the old error. Do not stop at the screen message; validate browser cache, CDN cache, DNS TTL, panel propagation, and stale application cache first.

Symptom checklist

• SELinux appears repeatedly in the Linux UI or logs.
• journalctl, disk, inode, memory, ulimit differs between successful and failed requests.
• The issue appears only after separating OS exhaustion from service configuration.
• It often follows deploys, permission changes, configuration edits, or data refreshes.

Likely causes

• SELinux specifically changes the investigation surface for Linux: verify the exact failing object, route, user, and timestamp before applying the broader pattern.
• The service unit starts with a different user, working directory, or environment than an interactive shell.
• journalctl contains the first failure while the service status only shows a summary.
• firewalld zone or rich rules allow the port in one network path but block another.
• cron runs with a minimal environment and different PATH.
• SELinux denies file, socket, or network access even when Unix permissions look correct.
• For the cache or propagation drift case, the first useful clue is browser cache, CDN cache, DNS TTL, panel propagation, and stale application cache.

First 1-minute checks

1. Write down the first failure time, latest change, affected user, path, and object ID.
2. Compare journalctl, disk, inode, memory, ulimit for success and failure in the same window.
3. Test the hypothesis: Linux operations failure caused by unit dependency, service logs, firewall zone, cron environment, or SELinux label policy.
4. Classify this as cache or propagation drift: browser cache, CDN cache, DNS TTL, panel propagation, and stale application cache.
5. Capture current values before changing configuration.

First evidence

Treat SELinux as a cache or propagation drift case. First collect evidence for browser cache, CDN cache, DNS TTL, panel propagation, and stale application cache.

Output examples

Normal output

Fresh requests and DNS answers show the same intended value from multiple networks.

Failing output

Only one resolver, browser, CDN edge, or cached object still returns the old value.

Output-to-action branches

• The panel says fixed but some users still see the old error.
  Separate DNS, CDN, browser, and application cache, then purge only the stale layer.
• The working and failing outputs differ.
  Act on the differing layer first: For SELinux, apply the fix only after reproducing the same condition and saving the before/after evidence for this exact code.
• Command output is normal but users still fail.
  Separate browser cache, cookies, permissions, and network location before declaring it fixed.

Do not do this

• Do not repeatedly edit correct DNS records just because a stale resolver is still visible.
• Do not change multiple layers before identifying the failing layer.
• Do not delete production data, grant broad permissions, or disable security controls as a first response.

Evidence quality

Auto-generated operator draft: includes issue-specific causes, commands, output branches, and unsafe-action warnings. Official-source links and real incident validation are queued for enrichment.

Commands to run first

grep -R "SELinux" ./logs

journalctl -u SERVICE -n 200 --no-pager

df -h && df -i

free -m

systemctl status SERVICE

systemctl status SERVICE

journalctl -u SERVICE -n 200 --no-pager

firewall-cmd --list-all || true

ausearch -m avc -ts recent || true

curl -I https://example.com -H 'Cache-Control: no-cache' && dig +trace example.com

Fix order

1. Record the full SELinux message, failing URL, user, object ID, and latest change.
2. Collect issue-specific evidence for Linux operations failure caused by unit dependency, service logs, firewall zone, cron environment, or SELinux label policy.
3. Compare the failing case with a successful case before editing settings.
4. If this is the cache or propagation drift branch, Separate DNS, CDN, browser, and application cache, then purge only the stale layer.
5. Re-check with the same command and URL, then record the normal output.

Actions by cause

• For SELinux, apply the fix only after reproducing the same condition and saving the before/after evidence for this exact code.
• Inspect systemd unit, journal logs, and effective environment together.
• Use journalctl for the first failure timestamp before restarting repeatedly.
• Check active firewalld zones and permanent versus runtime rules.
• Set explicit PATH, shell, and working directory for cron jobs.
• Use audit logs and restorecon/semanage rather than disabling SELinux blindly.
• For the cache or propagation drift branch, Separate DNS, CDN, browser, and application cache, then purge only the stale layer.

Evidence links

• systemd journalctl manual official
• Linux man-pages project official

Verification metadata

• operator-draft
• official-reference-linked
• 2026-07-23

Update queue

• Review cadence
  weekly-source-review
• Next enrichment
  Add one official-source check and one real output example for Linux SELinux.

Environment-specific checks

• Shared hosting, proxies, VPNs, or CDN layers can change OS exhaustion from service configuration results.
• Do not trust only the Linux UI; compare command output.
• Japanese hosting panels may show completion before DNS or SSL fully propagates.
• Test from both office and external networks.

Prevent it next time

• Store normal examples for journalctl, disk, inode, memory, ulimit.
• Add disk cleanup, ulimit, systemd unit, SELinux/firewalld to the release checklist.
• Keep recurring errors in the same note format.
• Split alerts by error rate, latency, certificates, disk, and permission changes.

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