docs: add user-management documentation

- CLI workflows for creating users and groups
- Troubleshooting guide (nscd, cache invalidation)
- Home directory behavior (UUID-based with symlinks)
- Update auth-system-replacement plan with progress

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

docs/plans/auth-system-replacement.md

@@ -66,9 +66,9 @@ This future migration path is a strong argument for Kanidm over LDAP-only soluti
    - Vault integration for idm_admin password
    - LDAPS on port 636
 
-2. **Configure declarative provisioning** ✅
+2. **Configure provisioning** ✅
-   - Groups: `admins`, `users`, `ssh-users`
+   - Groups provisioned declaratively: `admins`, `users`, `ssh-users`
-   - User: `torjus` (member of all groups)
+   - Users managed imperatively via CLI (allows setting POSIX passwords in one step)
    - POSIX attributes enabled (UID/GID range 65,536-69,999)
 
 3. **Test NAS integration** (in progress)
@@ -80,14 +80,16 @@ This future migration path is a strong argument for Kanidm over LDAP-only soluti
    - Grafana
    - Other services as needed
 
-5. **Create client module** in `system/` for PAM/NSS
+5. **Create client module** in `system/` for PAM/NSS ✅
-   - Enable on all hosts that need central auth
+   - Module: `system/kanidm-client.nix`
-   - Configure trusted CA
+   - `homelab.kanidm.enable = true` enables PAM/NSS
+   - Short usernames (not SPN format)
+   - Home directory symlinks via `home_alias`
+   - Enabled on test tier: testvm01, testvm02, testvm03
 
-6. **Documentation**
+6. **Documentation** ✅
-   - User management procedures
+   - `docs/user-management.md` - CLI workflows, troubleshooting
-   - Adding new OAuth2 clients
+   - User/group creation procedures verified working
-   - Troubleshooting PAM/NSS issues
 
 ## Progress
 
@@ -106,14 +108,37 @@ This future migration path is a strong argument for Kanidm over LDAP-only soluti
 - Prometheus monitoring scrape target configured
 
 **Provisioned entities:**
-- Groups: `admins`, `users`, `ssh-users`
+- Groups: `admins`, `users`, `ssh-users` (declarative)
-- User: `torjus` (member of all groups, POSIX enabled with GID 65536)
+- Users managed via CLI (imperative)
 
 **Verified working:**
 - WebUI login with idm_admin
 - LDAP bind and search with POSIX-enabled user
 - LDAPS with valid internal CA certificate
 
+### Completed (2026-02-08) - PAM/NSS Client
+
+**Client module deployed (`system/kanidm-client.nix`):**
+- `homelab.kanidm.enable = true` enables PAM/NSS integration
+- Connects to auth.home.2rjus.net
+- Short usernames (`torjus` instead of `torjus@home.2rjus.net`)
+- Home directory symlinks (`/home/torjus` → UUID-based dir)
+- Login restricted to `ssh-users` group
+
+**Enabled on test tier:**
+- testvm01, testvm02, testvm03
+
+**Verified working:**
+- User/group resolution via `getent`
+- SSH login with Kanidm unix passwords
+- Home directory creation with symlinks
+- Imperative user/group creation via CLI
+
+**Documentation:**
+- `docs/user-management.md` with full CLI workflows
+- Password requirements (min 10 chars)
+- Troubleshooting guide (nscd, cache invalidation)
+
 ### UID/GID Range (Resolved)
 
 **Range: 65,536 - 69,999** (manually allocated)
@@ -128,10 +153,9 @@ Rationale:
 
 ### Next Steps
 
-1. Deploy to monitoring01 to enable Prometheus scraping
+1. Enable PAM/NSS on production hosts (after test tier validation)
 2. Configure TrueNAS LDAP client for NAS integration testing
 3. Add OAuth2 clients (Grafana first)
-4. Create PAM/NSS client module for other hosts
 
 ## References
 

docs/plans/memory-issues-follow-up.md

@@ -0,0 +1,116 @@
+# Memory Issues Follow-up
+
+Tracking the zram change to verify it resolves OOM issues during nixos-upgrade on low-memory hosts.
+
+## Background
+
+On 2026-02-08, ns2 (2GB RAM) experienced an OOM kill during nixos-upgrade. The Nix evaluation process consumed ~1.6GB before being killed by the kernel. ns1 (manually increased to 4GB) succeeded with the same upgrade.
+
+Root cause: 2GB RAM is insufficient for Nix flake evaluation without swap.
+
+## Fix Applied
+
+**Commit:** `1674b6a` - system: enable zram swap for all hosts
+
+**Merged:** 2026-02-08 ~12:15 UTC
+
+**Change:** Added `zramSwap.enable = true` to `system/zram.nix`, providing ~2GB compressed swap on all hosts.
+
+## Timeline
+
+| Time (UTC) | Event |
+|------------|-------|
+| 05:00:46 | ns2 nixos-upgrade OOM killed |
+| 05:01:47 | `nixos_upgrade_failed` alert fired |
+| 12:15 | zram commit merged to master |
+| 12:19 | ns2 rebooted with zram enabled |
+| 12:20 | ns1 rebooted (memory reduced to 2GB via tofu) |
+
+## Hosts Affected
+
+All 2GB VMs that run nixos-upgrade:
+- ns1, ns2 (DNS)
+- vault01
+- testvm01, testvm02, testvm03
+- kanidm01
+
+## Metrics to Monitor
+
+Check these in Grafana or via PromQL to verify the fix:
+
+### Swap availability (should be ~2GB after upgrade)
+```promql
+node_memory_SwapTotal_bytes / 1024 / 1024
+```
+
+### Swap usage during upgrades
+```promql
+(node_memory_SwapTotal_bytes - node_memory_SwapFree_bytes) / 1024 / 1024
+```
+
+### Zswap compressed bytes (active compression)
+```promql
+node_memory_Zswap_bytes / 1024 / 1024
+```
+
+### Upgrade failures (should be 0)
+```promql
+node_systemd_unit_state{name="nixos-upgrade.service", state="failed"}
+```
+
+### Memory available during upgrades
+```promql
+node_memory_MemAvailable_bytes / 1024 / 1024
+```
+
+## Verification Steps
+
+After a few days (allow auto-upgrades to run on all hosts):
+
+1. Check all hosts have swap enabled:
+   ```promql
+   node_memory_SwapTotal_bytes > 0
+   ```
+
+2. Check for any upgrade failures since the fix:
+   ```promql
+   count_over_time(ALERTS{alertname="nixos_upgrade_failed"}[7d])
+   ```
+
+3. Review if any hosts used swap during upgrades (check historical graphs)
+
+## Success Criteria
+
+- No `nixos_upgrade_failed` alerts due to OOM after 2026-02-08
+- All hosts show ~2GB swap available
+- Upgrades complete successfully on 2GB VMs
+
+## Fallback Options
+
+If zram is insufficient:
+
+1. **Increase VM memory** - Update `terraform/vms.tf` to 4GB for affected hosts
+2. **Enable memory ballooning** - Configure VMs with dynamic memory allocation (see below)
+3. **Use remote builds** - Configure `nix.buildMachines` to offload evaluation
+4. **Reduce flake size** - Split configurations to reduce evaluation memory
+
+### Memory Ballooning
+
+Proxmox supports memory ballooning, which allows VMs to dynamically grow/shrink memory allocation based on demand. The balloon driver inside the guest communicates with the hypervisor to release or reclaim memory pages.
+
+Configuration in `terraform/vms.tf`:
+```hcl
+memory  = 4096  # maximum memory
+balloon = 2048  # minimum memory (shrinks to this when idle)
+```
+
+Pros:
+- VMs get memory on-demand without reboots
+- Better host memory utilization
+- Solves upgrade OOM without permanently allocating 4GB
+
+Cons:
+- Requires QEMU guest agent running in guest
+- Guest can experience memory pressure if host is overcommitted
+
+Ballooning and zram are complementary - ballooning provides headroom from the host, zram provides overflow within the guest.

docs/plans/security-hardening.md

@@ -0,0 +1,224 @@
+# Security Hardening Plan
+
+## Overview
+
+Address security gaps identified in infrastructure review. Focus areas: SSH hardening, network security, logging improvements, and secrets management.
+
+## Current State
+
+- SSH allows password auth and unrestricted root login (`system/sshd.nix`)
+- Firewall disabled on all hosts (`networking.firewall.enable = false`)
+- Promtail ships logs over HTTP to Loki
+- Loki has no authentication (`auth_enabled = false`)
+- AppRole secret-IDs never expire (`secret_id_ttl = 0`)
+- Vault TLS verification disabled by default (`skipTlsVerify = true`)
+- Audit logging exists (`common/ssh-audit.nix`) but not applied globally
+- Alert rules focus on availability, no security event detection
+
+## Priority Matrix
+
+| Issue | Severity | Effort | Priority |
+|-------|----------|--------|----------|
+| SSH password auth | High | Low | **P1** |
+| Firewall disabled | High | Medium | **P1** |
+| Promtail HTTP (no TLS) | High | Medium | **P2** |
+| No security alerting | Medium | Low | **P2** |
+| Audit logging not global | Low | Low | **P2** |
+| Loki no auth | Medium | Medium | **P3** |
+| Secret-ID TTL | Medium | Medium | **P3** |
+| Vault skipTlsVerify | Medium | Low | **P3** |
+
+## Phase 1: Quick Wins (P1)
+
+### 1.1 SSH Hardening
+
+Edit `system/sshd.nix`:
+
+```nix
+services.openssh = {
+  enable = true;
+  settings = {
+    PermitRootLogin = "prohibit-password";  # Key-only root login
+    PasswordAuthentication = false;
+    KbdInteractiveAuthentication = false;
+  };
+};
+```
+
+**Prerequisite:** Verify all hosts have SSH keys deployed for root.
+
+### 1.2 Enable Firewall
+
+Create `system/firewall.nix` with default deny policy:
+
+```nix
+{ ... }: {
+  networking.firewall.enable = true;
+
+  # Use openssh's built-in firewall integration
+  services.openssh.openFirewall = true;
+}
+```
+
+**Useful firewall options:**
+
+| Option | Description |
+|--------|-------------|
+| `networking.firewall.trustedInterfaces` | Accept all traffic from these interfaces (e.g., `[ "lo" ]`) |
+| `networking.firewall.interfaces.<name>.allowedTCPPorts` | Per-interface port rules |
+| `networking.firewall.extraInputRules` | Custom nftables rules (for complex filtering) |
+
+**Network range restrictions:** Consider restricting SSH to the infrastructure subnet (`10.69.13.0/24`) using `extraInputRules` for defense in depth. However, this adds complexity and may not be necessary given the trusted network model.
+
+#### Per-Interface Rules (http-proxy WireGuard)
+
+The `http-proxy` host has a WireGuard interface (`wg0`) that may need different rules than the LAN interface. Use `networking.firewall.interfaces` to apply per-interface policies:
+
+```nix
+# Example: http-proxy with different rules per interface
+networking.firewall = {
+  enable = true;
+
+  # Default: only SSH (via openFirewall)
+  allowedTCPPorts = [ ];
+
+  # LAN interface: allow HTTP/HTTPS
+  interfaces.ens18 = {
+    allowedTCPPorts = [ 80 443 ];
+  };
+
+  # WireGuard interface: restrict to specific services or trust fully
+  interfaces.wg0 = {
+    allowedTCPPorts = [ 80 443 ];
+    # Or use trustedInterfaces = [ "wg0" ] if fully trusted
+  };
+};
+```
+
+**TODO:** Investigate current WireGuard usage on http-proxy to determine appropriate rules.
+
+Then per-host, open required ports:
+
+| Host | Additional Ports |
+|------|------------------|
+| ns1/ns2 | 53 (TCP/UDP) |
+| vault01 | 8200 |
+| monitoring01 | 3100, 9090, 3000, 9093 |
+| http-proxy | 80, 443 |
+| nats1 | 4222 |
+| ha1 | 1883, 8123 |
+| jelly01 | 8096 |
+| nix-cache01 | 5000 |
+
+## Phase 2: Logging & Detection (P2)
+
+### 2.1 Enable TLS for Promtail → Loki
+
+Update `system/monitoring/logs.nix`:
+
+```nix
+clients = [{
+  url = "https://monitoring01.home.2rjus.net:3100/loki/api/v1/push";
+  tls_config = {
+    ca_file = "/etc/ssl/certs/homelab-root-ca.pem";
+  };
+}];
+```
+
+Requires:
+- Configure Loki with TLS certificate (use internal ACME)
+- Ensure all hosts trust root CA (already done via `system/pki/root-ca.nix`)
+
+### 2.2 Security Alert Rules
+
+Add to `services/monitoring/rules.yml`:
+
+```yaml
+- name: security_rules
+  rules:
+    - alert: ssh_auth_failures
+      expr: increase(node_logind_sessions_total[5m]) > 20
+      for: 0m
+      labels:
+        severity: warning
+      annotations:
+        summary: "Unusual login activity on {{ $labels.instance }}"
+
+    - alert: vault_secret_fetch_failure
+      expr: increase(vault_secret_failures[5m]) > 5
+      for: 0m
+      labels:
+        severity: warning
+      annotations:
+        summary: "Vault secret fetch failures on {{ $labels.instance }}"
+```
+
+Also add Loki-based alerts for:
+- Failed SSH attempts: `{job="systemd-journal"} |= "Failed password"`
+- sudo usage: `{job="systemd-journal"} |= "sudo"`
+
+### 2.3 Global Audit Logging
+
+Add `./common/ssh-audit.nix` import to `system/default.nix`:
+
+```nix
+imports = [
+  # ... existing imports
+  ../common/ssh-audit.nix
+];
+```
+
+## Phase 3: Defense in Depth (P3)
+
+### 3.1 Loki Authentication
+
+Options:
+1. **Basic auth via reverse proxy** - Put Loki behind Caddy with auth
+2. **Loki multi-tenancy** - Enable `auth_enabled = true` and use tenant IDs
+3. **Network isolation** - Bind Loki only to localhost, expose via authenticated proxy
+
+Recommendation: Option 1 (reverse proxy) is simplest for homelab.
+
+### 3.2 AppRole Secret Rotation
+
+Update `terraform/vault/approle.tf`:
+
+```hcl
+secret_id_ttl  = 2592000  # 30 days
+```
+
+Add documentation for manual rotation procedure or implement automated rotation via the existing `restartTrigger` mechanism in `vault-secrets.nix`.
+
+### 3.3 Enable Vault TLS Verification
+
+Change default in `system/vault-secrets.nix`:
+
+```nix
+skipTlsVerify = mkOption {
+  type = types.bool;
+  default = false;  # Changed from true
+};
+```
+
+**Prerequisite:** Verify all hosts trust the internal CA that signed the Vault certificate.
+
+## Implementation Order
+
+1. **Test on test-tier first** - Deploy phases 1-2 to testvm01/02/03
+2. **Validate SSH access** - Ensure key-based login works before disabling passwords
+3. **Document firewall ports** - Create reference of ports per host before enabling
+4. **Phase prod rollout** - Deploy to prod hosts one at a time, verify each
+
+## Open Questions
+
+- [ ] Do all hosts have SSH keys configured for root access?
+- [ ] Should firewall rules be per-host or use a central definition with roles?
+- [ ] Should Loki authentication use the existing Kanidm setup?
+
+**Resolved:** Password-based SSH access for recovery is not required - most hosts have console access through Proxmox or physical access, which provides an out-of-band recovery path if SSH keys fail.
+
+## Notes
+
+- Firewall changes are the highest risk - test thoroughly on test-tier
+- SSH hardening must not lock out access - verify keys first
+- Consider creating a "break glass" procedure for emergency access if keys fail

docs/user-management.md

@@ -0,0 +1,267 @@
+# User Management with Kanidm
+
+Central authentication for the homelab using Kanidm.
+
+## Overview
+
+- **Server**: kanidm01.home.2rjus.net (auth.home.2rjus.net)
+- **WebUI**: https://auth.home.2rjus.net
+- **LDAPS**: port 636
+
+## CLI Setup
+
+The `kanidm` CLI is available in the devshell:
+
+```bash
+nix develop
+
+# Login as idm_admin
+kanidm login --name idm_admin --url https://auth.home.2rjus.net
+```
+
+## User Management
+
+POSIX users are managed imperatively via the `kanidm` CLI. This allows setting
+all attributes (including UNIX password) in one workflow.
+
+### Creating a POSIX User
+
+```bash
+# Create the person
+kanidm person create <username> "<Display Name>"
+
+# Add to groups
+kanidm group add-members ssh-users <username>
+
+# Enable POSIX (UID is auto-assigned)
+kanidm person posix set <username>
+
+# Set UNIX password (required for SSH login, min 10 characters)
+kanidm person posix set-password <username>
+
+# Optionally set login shell
+kanidm person posix set <username> --shell /bin/zsh
+```
+
+### Example: Full User Creation
+
+```bash
+kanidm person create testuser "Test User"
+kanidm group add-members ssh-users testuser
+kanidm person posix set testuser
+kanidm person posix set-password testuser
+kanidm person get testuser
+```
+
+After creation, verify on a client host:
+```bash
+getent passwd testuser
+ssh testuser@testvm01.home.2rjus.net
+```
+
+### Viewing User Details
+
+```bash
+kanidm person get <username>
+```
+
+### Removing a User
+
+```bash
+kanidm person delete <username>
+```
+
+## Group Management
+
+Groups for POSIX access are also managed via CLI.
+
+### Creating a POSIX Group
+
+```bash
+# Create the group
+kanidm group create <group-name>
+
+# Enable POSIX with a specific GID
+kanidm group posix set <group-name> --gidnumber <gid>
+```
+
+### Adding Members
+
+```bash
+kanidm group add-members <group-name> <username>
+```
+
+### Viewing Group Details
+
+```bash
+kanidm group get <group-name>
+kanidm group list-members <group-name>
+```
+
+### Example: Full Group Creation
+
+```bash
+kanidm group create testgroup
+kanidm group posix set testgroup --gidnumber 68010
+kanidm group add-members testgroup testuser
+kanidm group get testgroup
+```
+
+After creation, verify on a client host:
+```bash
+getent group testgroup
+```
+
+### Current Groups
+
+| Group | GID | Purpose |
+|-------|-----|---------|
+| ssh-users | 68000 | SSH login access |
+| admins | 68001 | Administrative access |
+| users | 68002 | General users |
+
+### UID/GID Allocation
+
+Kanidm auto-assigns UIDs/GIDs from its configured range. For manually assigned GIDs:
+
+| Range | Purpose |
+|-------|---------|
+| 65,536+ | Users (auto-assigned) |
+| 68,000 - 68,999 | Groups (manually assigned) |
+
+## PAM/NSS Client Configuration
+
+Enable central authentication on a host:
+
+```nix
+homelab.kanidm.enable = true;
+```
+
+This configures:
+- `services.kanidm.enablePam = true`
+- Client connection to auth.home.2rjus.net
+- Login authorization for `ssh-users` group
+- Short usernames (`torjus` instead of `torjus@home.2rjus.net`)
+- Home directory symlinks (`/home/torjus` → UUID-based directory)
+
+### Enabled Hosts
+
+- testvm01, testvm02, testvm03 (test tier)
+
+### Options
+
+```nix
+homelab.kanidm = {
+  enable = true;
+  server = "https://auth.home.2rjus.net";  # default
+  allowedLoginGroups = [ "ssh-users" ];     # default
+};
+```
+
+### Home Directories
+
+Home directories use UUID-based paths for stability (so renaming a user doesn't
+require moving their home directory). Symlinks provide convenient access:
+
+```
+/home/torjus -> /home/e4f4c56c-4aee-4c20-846f-90cb69807733
+```
+
+The symlinks are created by `kanidm-unixd-tasks` on first login.
+
+## Testing
+
+### Verify NSS Resolution
+
+```bash
+# Check user resolution
+getent passwd <username>
+
+# Check group resolution
+getent group <group-name>
+```
+
+### Test SSH Login
+
+```bash
+ssh <username>@<hostname>.home.2rjus.net
+```
+
+## Troubleshooting
+
+### "PAM user mismatch" error
+
+SSH fails with "fatal: PAM user mismatch" in logs. This happens when Kanidm returns
+usernames in SPN format (`torjus@home.2rjus.net`) but SSH expects short names (`torjus`).
+
+**Solution**: Configure `uid_attr_map = "name"` in unixSettings (already set in our module).
+
+Check current format:
+```bash
+getent passwd torjus
+# Should show: torjus:x:65536:...
+# NOT: torjus@home.2rjus.net:x:65536:...
+```
+
+### User resolves but SSH fails immediately
+
+The user's login group (e.g., `ssh-users`) likely doesn't have POSIX enabled:
+
+```bash
+# Check if group has POSIX
+getent group ssh-users
+
+# If empty, enable POSIX on the server
+kanidm group posix set ssh-users --gidnumber 68000
+```
+
+### User doesn't resolve via getent
+
+1. Check kanidm-unixd service is running:
+   ```bash
+   systemctl status kanidm-unixd
+   ```
+
+2. Check unixd can reach server:
+   ```bash
+   kanidm-unix status
+   # Should show: system: online, Kanidm: online
+   ```
+
+3. Check client can reach server:
+   ```bash
+   curl -s https://auth.home.2rjus.net/status
+   ```
+
+4. Check user has POSIX enabled on server:
+   ```bash
+   kanidm person get <username>
+   ```
+
+5. Restart nscd to clear stale cache:
+   ```bash
+   systemctl restart nscd
+   ```
+
+6. Invalidate kanidm cache:
+   ```bash
+   kanidm-unix cache-invalidate
+   ```
+
+### Changes not taking effect after deployment
+
+NixOS uses nsncd (a Rust reimplementation of nscd) for NSS caching. After deploying
+kanidm-unixd config changes, you may need to restart both services:
+
+```bash
+systemctl restart kanidm-unixd
+systemctl restart nscd
+```
+
+### Test PAM authentication directly
+
+Use the kanidm-unix CLI to test PAM auth without SSH:
+
+```bash
+kanidm-unix auth-test --name <username>
+```

flake.nix

@@ -207,6 +207,7 @@
               pkgs.ansible
               pkgs.opentofu
               pkgs.openbao
+              pkgs.kanidm_1_8
               (pkgs.callPackage ./scripts/create-host { })
               homelab-deploy.packages.${pkgs.system}.default
             ];

hosts/jelly01/configuration.nix

@@ -64,9 +64,5 @@
   vault.enable = true;
   homelab.deploy.enable = true;
 
-  zramSwap = {
-    enable = true;
-  };
-
   system.stateVersion = "23.11"; # Did you read the comment?
 }

hosts/nix-cache01/default.nix

@@ -4,6 +4,5 @@
     ./configuration.nix
     ../../services/nix-cache
     ../../services/actions-runner
-    ./zram.nix
   ];
 }

hosts/nix-cache01/zram.nix

@@ -1,6 +0,0 @@
-{ ... }:
-{
-  zramSwap = {
-    enable = true;
-  };
-}

hosts/template2/configuration.nix

@@ -79,5 +79,8 @@
   # Or disable the firewall altogether.
   networking.firewall.enable = false;
 
+  # Compressed swap in RAM - prevents OOM during bootstrap nixos-rebuild
+  zramSwap.enable = true;
+
   system.stateVersion = "25.11";
 }

hosts/testvm01/configuration.nix

@@ -25,6 +25,9 @@
   # Enable remote deployment via NATS
   homelab.deploy.enable = true;
 
+  # Enable Kanidm PAM/NSS for central authentication
+  homelab.kanidm.enable = true;
+
   nixpkgs.config.allowUnfree = true;
   boot.loader.grub.enable = true;
   boot.loader.grub.device = "/dev/vda";

hosts/testvm02/configuration.nix

@@ -25,6 +25,9 @@
   # Enable remote deployment via NATS
   homelab.deploy.enable = true;
 
+  # Enable Kanidm PAM/NSS for central authentication
+  homelab.kanidm.enable = true;
+
   nixpkgs.config.allowUnfree = true;
   boot.loader.grub.enable = true;
   boot.loader.grub.device = "/dev/vda";

hosts/testvm03/configuration.nix

@@ -25,6 +25,9 @@
   # Enable remote deployment via NATS
   homelab.deploy.enable = true;
 
+  # Enable Kanidm PAM/NSS for central authentication
+  homelab.kanidm.enable = true;
+
   nixpkgs.config.allowUnfree = true;
   boot.loader.grub.enable = true;
   boot.loader.grub.device = "/dev/vda";

services/kanidm/default.nix

@@ -17,7 +17,8 @@
       };
     };
 
-    # Provisioning - initial users/groups
+    # Provision base groups only - users are managed via CLI
+    # See docs/user-management.md for details
     provision = {
       enable = true;
       idmAdminPasswordFile = config.vault.secrets.kanidm-idm-admin.outputDir;
@@ -28,10 +29,7 @@
         ssh-users = { };
       };
 
-      persons.torjus = {
+      # Regular users (persons) are managed imperatively via kanidm CLI
-        displayName = "Torjus";
-        groups = [ "admins" "users" "ssh-users" ];
-      };
     };
   };
 
@@ -46,7 +44,7 @@
     extraDomainNames = [ "${config.networking.hostName}.home.2rjus.net" ];
   };
 
-  # Vault secret for idm_admin password
+  # Vault secret for idm_admin password (used for provisioning)
   vault.secrets.kanidm-idm-admin = {
     secretPath = "kanidm/idm-admin-password";
     extractKey = "password";

system/default.nix

@@ -4,6 +4,7 @@
     ./acme.nix
     ./autoupgrade.nix
     ./homelab-deploy.nix
+    ./kanidm-client.nix
     ./monitoring
     ./motd.nix
     ./packages.nix
@@ -12,5 +13,6 @@
     ./pki/root-ca.nix
     ./sshd.nix
     ./vault-secrets.nix
+    ./zram.nix
   ];
 }

system/kanidm-client.nix

@@ -0,0 +1,42 @@
+{ lib, config, pkgs, ... }:
+let
+  cfg = config.homelab.kanidm;
+in
+{
+  options.homelab.kanidm = {
+    enable = lib.mkEnableOption "Kanidm PAM/NSS client for central authentication";
+
+    server = lib.mkOption {
+      type = lib.types.str;
+      default = "https://auth.home.2rjus.net";
+      description = "URI of the Kanidm server";
+    };
+
+    allowedLoginGroups = lib.mkOption {
+      type = lib.types.listOf lib.types.str;
+      default = [ "ssh-users" ];
+      description = "Groups allowed to log in via PAM";
+    };
+  };
+
+  config = lib.mkIf cfg.enable {
+    services.kanidm = {
+      package = pkgs.kanidm_1_8;
+      enablePam = true;
+
+      clientSettings = {
+        uri = cfg.server;
+      };
+
+      unixSettings = {
+        pam_allowed_login_groups = cfg.allowedLoginGroups;
+        # Use short names (torjus) instead of SPN format (torjus@home.2rjus.net)
+        # This prevents "PAM user mismatch" errors with SSH
+        uid_attr_map = "name";
+        gid_attr_map = "name";
+        # Create symlink /home/torjus -> /home/torjus@home.2rjus.net
+        home_alias = "name";
+      };
+    };
+  };
+}

system/zram.nix

@@ -0,0 +1,8 @@
+# Compressed swap in RAM
+#
+# Provides overflow memory during Nix builds and upgrades.
+# Prevents OOM kills on low-memory hosts (2GB VMs).
+{ ... }:
+{
+  zramSwap.enable = true;
+}