Claude
b6af49f1f1
When configuring CrowdSec, optionally wire up an ntfy push notification via CrowdSec's HTTP notification plugin: writes /etc/crowdsec/notifications/ntfy.yaml and references it from the default profile in profiles.yaml. Alerts fire on a ban decision (after repeated failed attempts), not on every failed login. Document the behavior in SCRIPT-VARIANTS.md, including why Authelia (email-only) doesn't cover failed-login push. Both crowdsec variants verified with 'bash -n' and a --dry-run --unattended pass (exit 0). https://claude.ai/code/session_017eA2qqq9jfF2tNtpUYL8vK
69 lines
3.2 KiB
Markdown
69 lines
3.2 KiB
Markdown
# Install Script Variants
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This repo ships the post-install script in three tiers, for both Ubuntu 24.04
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and 26.04. Pick **one** and run it — they are mutually exclusive (each is a
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complete, standalone script).
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| File | Keycloak | SSO | Intrusion prevention |
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|------|----------|-----|----------------------|
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| `ubuntu-post-install-<ver>.sh` | ✅ included | Keycloak **or** Authelia | fail2ban (SSH + Caddy) |
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| `ubuntu-post-install-<ver>-no-keycloak.sh` | ❌ removed | Authelia | fail2ban (SSH + Caddy) |
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| `ubuntu-post-install-<ver>-crowdsec.sh` | ❌ removed | Authelia | **CrowdSec** (replaces fail2ban) |
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`<ver>` is `24.04` or `26.04`.
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## Which one?
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- **Original (`.sh`)** — unchanged baseline, kept for fallback. Still offers
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Keycloak in the menu.
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- **`-no-keycloak`** — same as original but with Keycloak fully removed.
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Authelia is the SSO + 2FA option. Use this if you never got Keycloak running
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and have standardized on Authelia.
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- **`-crowdsec`** — builds on `-no-keycloak` and swaps fail2ban out for
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[CrowdSec](https://www.crowdsec.net/):
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- SSH brute-force protection (CrowdSec reads `/var/log/auth.log` via the
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`crowdsecurity/sshd` collection)
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- Caddy HTTP auth abuse (the `crowdsecurity/caddy` collection + a log
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acquisition at `/etc/crowdsec/acquis.d/caddy.yaml`)
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- Enforcement via `crowdsec-firewall-bouncer-iptables`
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- **Geo-blocking + community IP-reputation blocklists** — the capability
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that fail2ban and Authelia both lack
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- **Optional ntfy alerts on bans** — when configuring CrowdSec the script
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can wire up an [ntfy](https://ntfy.sh/) push notification (via CrowdSec's
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HTTP notification plugin). It writes `/etc/crowdsec/notifications/ntfy.yaml`
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and references it from the default profile in
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`/etc/crowdsec/profiles.yaml`. The same script can also install a
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self-hosted **ntfy server** (separate menu option), so alerts can stay on
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your own infrastructure.
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### A note on "notification of failed attempts"
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CrowdSec alerts fire on a **ban decision** — i.e. once an IP crosses the
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failed-attempt threshold for a scenario (e.g. `crowdsecurity/ssh-bf`), not on
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every individual failed login. That gives you one actionable "X banned for Y"
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push instead of a flood. To alert on a single failed login you'd lower the
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scenario threshold or write a custom scenario, but the ban-level alert is the
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recommended default.
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Authelia, by contrast, only sends **email/SMTP** notifications (for password
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reset and 2FA device registration) — it has no built-in "failed login" push,
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which is why CrowdSec → ntfy is the path used here.
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## Notes on the security layers
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- **Authelia** handles per-account failed-login *regulation* (lockout). It does
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**not** do geo-blocking.
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- **fail2ban** bans IPs at the firewall based on Caddy log patterns
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(401/403/429). No geo-blocking, not credential-aware.
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- **CrowdSec** covers SSH + Caddy from a single agent, adds geo/ASN enrichment
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and crowd-sourced reputation, and is the modern successor to fail2ban.
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Useful CrowdSec commands after install:
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```bash
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sudo cscli metrics # overview / parsing health
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sudo cscli decisions list # current bans
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sudo cscli alerts list # detections
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sudo cscli decisions delete --ip <IP> # unban
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```
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