Documents the non-obvious failure mode where /etc/hosts generator scripts
using `tailscale status --json | jq '.HostName'` get poisoned by iOS
peers, which always report HostName as the literal string "localhost"
because iOS doesn't expose the device name to apps.
Includes the buggy and fixed jq filter (use .DNSName first label
instead), a real-world Postfix outage example, and a verification
checklist. Linked from troubleshooting index and SUMMARY.
Discovered while diagnosing a 24h Postfix outage on majordiscord.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Documents the gotcha discovered during the 2026-04-30 DCAProd XML-RPC
outage triage: wp-fail2ban plugin emits via PHP syslog(LOG_AUTH) which
lands in /var/log/auth.log on Debian/Ubuntu, not /var/log/syslog.
wordpress-{hard,soft,extra} jails configured with logpath=/var/log/syslog
(common in tutorials and ansible roles) silently catch zero events.
Article includes diagnostic steps, the fix, fail2ban-regex verification,
distro cheat sheet (Debian/Ubuntu vs RHEL/Fedora vs systemd-journal-only),
and a note on why wordpress-login is unaffected.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Two articles surfaced during the v8 deploy + eval on 2026-04-25:
- Ollama: `ollama run` with piped stdin bypasses the chat template and
SYSTEM prompt — output looks like raw base-model completion. Caught
during initial v8 smoke test. Fix: use /api/chat HTTP endpoint.
- rsync over Tailscale can hang in TCP teardown after the data has
fully transferred. Verify with md5sum, then kill the hung pipeline.
Includes a watcher-threshold gotcha (set below true file size, not
above) and prevention tips.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Covers creating groups, assigning clients, scoping allow rules to
specific groups via API and CLI. Includes ghost attribution gotcha
(router DNS proxy + secondary DNS causes FTL cache mis-attribution)
and the fix (Pi-hole as sole DNS, remove secondary).
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
New article covering the conversion from per-ban email alerts to a
three-tier model (silent default, sshd/recidive immediate, daily digest).
Includes Ansible automation, gotchas with lineinfile regex collisions,
and fq-hostname override for clean subjects.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Articles from prior sessions that were written locally but never shipped:
- 02-selfhosting/cloud/aws-s3-cost-management.md — lifecycle rules, storage class selection, bucket inventory, unexpected-growth investigation
- 02-selfhosting/dns-networking/wake-on-lan-router-ssh.md — WOL magic packets via Asus router SSH + ether-wake, Ansible vault integration
- 02-selfhosting/services/claude-code-remote-control.md — mobile access to a persistent host Claude Code session
Nav updated (index.md + SUMMARY.md):
- Added Cloud subsection under Self-Hosting for aws-s3
- Added wake-on-lan and aws-s3 entries to SUMMARY
- Added claude-code-remote-control to index's Services section
- Added ansible-ssh-host-alias-bypass nav entry (article shipped in 2dbeb22)
- Article count 87 → 89, self-hosting 30 → 32, troubleshooting 33 → 34
Documents the 2026-04-09 scanner incident where 301-redirected PHP probes
bypassed the existing apache-404scan jail, leaving the scanner unbanned
and firing Netdata web_log_1m_redirects alerts. New jail catches 301/302/
403/404 PHP responses while excluding legitimate WordPress endpoints.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Captures the majorlab incident where the backup watchdog emailed a missing
heartbeat after a kernel-update reboot wiped /var/run, even though the
backup had actually completed cleanly. Documents the tmpfs root cause and
the fix of storing heartbeats under /var/lib instead.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Covers shell quoting for URLs containing &, ?, #, and other characters
that Bash interprets as operators. Common gotcha when downloading from
CDNs with token-based URLs.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Corrected inflated article count (was 76, actual is 73).
Updated domain breakdown and frontmatter timestamps from Obsidian.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Access-log-based filter for wp-login.php brute force detection without
requiring the WP fail2ban plugin. Documents the backend=polling gotcha
on Ubuntu 24.04 and manual banning workflow.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
New article: selinux-fail2ban-execmem-fix.md — custom policy module
for fail2ban grep execmem denial on Fedora 43.
Also includes previously uncommitted:
- n8n-proxy-trust-x-forwarded-for.md
- fail2ban-apache-404-scanner-jail.md updates
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Documents the N8N_PROXY_HOPS env var needed for n8n behind Caddy/Nginx
when N8N_TRUST_PROXY alone is insufficient in newer versions.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Covers version checking, pinned-tag update process, SQLite password
reset, and why Arcane may not catch updates when the latest tag lags
behind npm releases.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Documents the SSH keepalive fix for dnf upgrade timeouts on Fedora hosts,
plus the do-agent task guard fix. Also adds Ansible & Fleet Management
section to the troubleshooting index.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
New guide for custom access-log-based fail2ban jail that catches
rapid-fire 404 vulnerability scanners missed by default error-log jails.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Add troubleshooting article for the 2026-03-27 incident where PHP-FPM
hung after the nightly update cycle. Update the Netdata Docker alarm
tuning article with the dedicated Nextcloud alarm split and the new
watchdog cron deployed to majorlab. (54 articles)
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Documents the 2026-03-14 incident where MajorAir's public IP was banned
by the postfix-sasl jail after repeated SASL auth failures, silently
blocking all IMAP connections from Spark Desktop.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Add troubleshooting article covering the three-part failure mode on
Fedora with SELinux Enforcing: docker.socket disabled, ports 4443/8448
blocked, and httpd_can_network_connect off. Update index and SUMMARY.
