# LOGAR Linux Edge Forwarder

Standalone compiled binary distribution for Linux edge servers running systemd.

---

## Overview
`Linux_Client.bin` is a self-contained, pre-compiled executable that queries `systemd-journald` via `journalctl`, filters logs directly at the source, encrypts the payload using OpenPGP, and streams candidate events over an authenticated TCP socket to the central LOGAR hub.

### Key Capabilities
- **Pre-compiled & Dependency-Free**: Ships as a standalone executable binary (`Linux_Client.bin`). No Python environment, pip packages, or GnuPG binaries are required on the host.
- **Source-Level Filtering**: Retains events spanning `INFO`, `WARNING`, and `ERROR` (`journalctl -p info`). Drops debug noise (priority 7) and skips events older than 24 hours.
- **State Tracking & Deduplication**: Maintains persistent client state in `client_state.json` (tracking systemd journalctl cursors and microsecond timestamps) so every log record is forwarded exactly once without duplicates.
- **Fail-Safe State Commit**: State is committed only when the server returns a verified `success` response. In the event of a network outage, state remains unchanged and unsent events are retried automatically on the next run.
- **End-to-End Encryption**: Encrypts payloads using the server's OpenPGP public key before transmission.

---

## 1. Generating & Deploying the Configuration File

### Step 1: Generate `client_config.json` on the Server
Run the following command on your central LOGAR server to export a client bundle tailored for your environment:

```bash
python src/Server.py --create-client-config --server-host <SERVER_IP_OR_DNS> --server-port 9443 --client-out client_config.json
```

- Replace `<SERVER_IP_OR_DNS>` with the reachable IP address or FQDN of your central LOGAR server hub.
- Default TCP port is `9443`.

### Step 2: Configuration Structure
The generated `client_config.json` contains:

```json
{
  "server_host": "192.168.1.100",
  "server_port": 9443,
  "server_fingerprint": "375388960531264EA0648EC0D2C4E4ABC6F22AC2",
  "server_public_key": "-----BEGIN PGP PUBLIC KEY BLOCK-----\n...",
  "auth_token": "a1b2c3d4e5f6..."
}
```

> [!NOTE]
> A reference example is provided in `client_config.sample.json`. The configuration file contains **no host-specific names or site names** to ensure client anonymity and easy redistribution.

### Step 3: Copy to Edge Node
Place `Linux_Client.bin` and `client_config.json` into the target directory (recommended: `/opt/logar/`):

```bash
sudo mkdir -p /opt/logar
sudo cp Linux_Client.bin client_config.json /opt/logar/
sudo chmod +x /opt/logar/Linux_Client.bin
```

---

## 2. Running Manually

Test the forwarder interactively:

```bash
cd /opt/logar
./Linux_Client.bin --hours 24
```

### Command-Line Arguments
| Argument | Default | Description |
| :--- | :--- | :--- |
| `--config` | `client_config.json` | Path to client configuration file |
| `--hours` | `24` | Lookback window in hours for journal logs |
| `--state-file` | `client_state.json` | Path to persistent state file |
| `--no-state` | `False` | Disable state tracking and send all events matching lookback window |

---

## 3. Installing as a Systemd Service & Timer (Recommended)

Running `Linux_Client.bin` via a systemd timer ensures reliable periodic execution, automatic restart, and native log integration with `journalctl`.

### Step 1: Create the Systemd Service Unit
Create `/etc/systemd/system/logar-forwarder.service`:

```ini
[Unit]
Description=LOGAR Edge Log Forwarder
After=network-online.target
Wants=network-online.target

[Service]
Type=oneshot
WorkingDirectory=/opt/logar
ExecStart=/opt/logar/Linux_Client.bin --hours 24
User=root
StandardOutput=journal
StandardError=journal

[Install]
WantedBy=multi-user.target
```

### Step 2: Create the Systemd Timer Unit
Create `/etc/systemd/system/logar-forwarder.timer` to execute the forwarder every 3 hours (with a 5-minute initial delay upon boot):

```ini
[Unit]
Description=Run LOGAR Edge Forwarder periodically
Requires=logar-forwarder.service

[Timer]
OnBootSec=5min
OnUnitActiveSec=3h
Persistent=true

[Install]
WantedBy=timers.target
```

### Step 3: Enable and Start the Timer
```bash
sudo systemctl daemon-reload
sudo systemctl enable --now logar-forwarder.timer
```

### Step 4: Verify Timer & Service Status
```bash
# Check timer schedule
sudo systemctl list-timers --all | grep logar

# Trigger an immediate manual execution
sudo systemctl start logar-forwarder.service

# View execution logs
sudo journalctl -u logar-forwarder.service -n 50
```

---

## 4. Alternative: Cron Job Deployment

If systemd timers are not preferred, configure a periodic cron job running every 3 hours:

```bash
# Open root crontab
sudo crontab -e

# Add the following entry:
0 */3 * * * cd /opt/logar && ./Linux_Client.bin --hours 24 >> /var/log/logar_forwarder.log 2>&1
```