Test LimaCharlie EDR

Deploy a temporary LimaCharlie EDR sensor on the local Linux or Mac OS host for testing purposes. The sensor runs in the background with automatic cleanup when stopped.

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LimaCharlie Integration

Prerequisites: Run /init-lc to initialize LimaCharlie context.

LimaCharlie CLI Access

All LimaCharlie operations use the limacharlie CLI directly:

limacharlie <noun> <verb> --oid <oid> --output yaml [flags]

For command help and discovery: limacharlie <command> --ai-help

Critical Rules

Rule	Wrong	Right
CLI Access	Call MCP tools or spawn api-executor	Use Bash("limacharlie ...") directly
Output Format	--output json	--output yaml (more token-efficient)
Filter Output	Pipe to jq/yq	Use --filter JMESPATH to select fields
LCQL Queries	Write query syntax manually	Use limacharlie ai generate-query first
Timestamps	Calculate epoch values	Use date +%s or date -d '7 days ago' +%s
OID	Use org name	Use UUID (call limacharlie org list if needed)

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When to Use

Use this skill when:

• Testing D&R rules: Validate detection rules against live sensor data from your own machine
• Investigating sensor behavior: Understand what events the sensor generates for specific actions
• Development and debugging: Test detections in a controlled environment
• Quick validation: Verify your LimaCharlie setup is working correctly
• Learning: Explore LimaCharlie capabilities hands-on

What This Skill Does

This skill performs a two-phase deployment:

1. Phase 1 - Installation Key: Creates or finds an existing "Test EDR" installation key in your selected LimaCharlie organization
2. Phase 2 - Sensor Deployment: Downloads the appropriate EDR agent for your platform (Linux or Mac OS) to a temporary directory and runs it in the background as root

The sensor:

• Runs in the background (non-blocking)
• Uses a unique temp directory (avoids file conflicts)
• Requires root/sudo for full system monitoring
• Cleans up automatically when stopped

Required Information

Before starting, ensure you have:

• LimaCharlie organization: Select from your available orgs or create a new one
• Linux or Mac OS host: Supports Linux x64, Mac Intel (x64), and Mac Apple Silicon (arm64)
• Internet access: Required to download the sensor binary
• Root/sudo access: The sensor needs elevated privileges for proper monitoring

How to Use

Pre-requisite: Select an Organization

First, get the list of available organizations:

limacharlie org list --output yaml

This returns your available organizations. Use AskUserQuestion to let the user select one, or if they need a new org, create one with limacharlie org create --name "<name>" --output yaml.

Phase 1: Get or Create Installation Key

Check for existing "Test EDR" installation key:

limacharlie installation-key list --oid <SELECTED_ORG_ID> --filter "[?description=='Test EDR'] | [0]" --output yaml

If "Test EDR" key exists: Extract the key value from the response.

If not exists: Create one:

limacharlie installation-key create --description "Test EDR" --tags "test-edr,temporary" --oid <SELECTED_ORG_ID> --output yaml

Save the returned key value for the next phase.

Phase 2: Download and Run the EDR

Step 1: Detect platform and create temp directory:

OS_TYPE=$(uname -s)
ARCH=$(uname -m)
TEMP_DIR=$(mktemp -d "${TMPDIR:-/tmp}/lc-edr-test-XXXXXX")
echo "Platform: $OS_TYPE ($ARCH), Temp dir: $TEMP_DIR"

Step 2: Download the appropriate sensor binary:

if [ "$OS_TYPE" = "Darwin" ]; then
  if [ "$ARCH" = "arm64" ]; then
    DOWNLOAD_URL="https://downloads.limacharlie.io/sensor/mac/arm64"
  else
    DOWNLOAD_URL="https://downloads.limacharlie.io/sensor/mac/64"
  fi
else
  DOWNLOAD_URL="https://downloads.limacharlie.io/sensor/linux/64"
fi
curl -sSL "$DOWNLOAD_URL" -o "$TEMP_DIR/lc_sensor"
chmod +x "$TEMP_DIR/lc_sensor"
echo "Sensor downloaded to: $TEMP_DIR"

Step 3: Run the sensor in background (as root):

if [ "$OS_TYPE" = "Darwin" ]; then
  sudo nohup "$TEMP_DIR/lc_sensor" -d <INSTALLATION_KEY> > /dev/null 2>&1 &
else
  sudo setsid "$TEMP_DIR/lc_sensor" -d <INSTALLATION_KEY> > /dev/null 2>&1 &
fi
echo "Sensor started in $TEMP_DIR"

Important:

• Linux uses setsid to create a new session and fully detach from the terminal
• Mac OS uses nohup which achieves similar process detachment
• Both approaches prevent Claude Code from hanging while waiting for the process
• Store the TEMP_DIR path for cleanup later
• The sensor process name is lc_sensor - use this for stopping

Verify Sensor Connection

After starting, the sensor should appear in your LimaCharlie organization within a few seconds. Verify by listing sensors with a selector that matches the installation key's iid (Installation ID, a UUID):

limacharlie sensor list --selector "iid == \`<INSTALLATION_KEY_IID>\`" --oid <SELECTED_ORG_ID> --output yaml

Replace <INSTALLATION_KEY_IID> with the iid UUID from the installation key used. This selector fetches only the sensor enrolled with that specific installation key, rather than listing all sensors in the organization.

Stopping and Cleanup

When the user wants to stop the test EDR:

Single command to stop and clean up (recommended):

sudo pkill -9 -f lc_sensor; sudo rm -rf <TEMP_DIR>; echo "Cleanup complete"

Important notes:

• Use -9 (SIGKILL) for reliable termination of detached processes
• Use ; instead of && - pkill returns non-zero exit codes even on success (e.g., 144 when the signal is delivered)
• Do NOT use KillShell to stop the sensor - always use pkill

Verify cleanup succeeded:

ps aux | grep "[l]c_sensor" || echo "Sensor stopped"

The [l] bracket trick prevents grep from matching itself in the output.

Example Usage

Example 1: Full Deployment Workflow

User: "I want to test the LimaCharlie EDR on my machine"

Steps:

1. List organizations:

limacharlie org list --output yaml

Response shows: [{"name": "My Test Org", "oid": "abc123-def456-..."}]

2. Ask user to select org (via AskUserQuestion)

3. Check for existing installation key:

limacharlie installation-key list --oid abc123-def456-... --filter "[?description=='Test EDR'] | [0]" --output yaml

4. Create installation key if needed:

limacharlie installation-key create --description "Test EDR" --tags "test-edr,temporary" --oid abc123-def456-... --output yaml

Returns: {"iid": "test-edr", "key": "abc123:def456:..."}

5. Download and run sensor:

OS_TYPE=$(uname -s)
ARCH=$(uname -m)
TEMP_DIR=$(mktemp -d "${TMPDIR:-/tmp}/lc-edr-test-XXXXXX")

if [ "$OS_TYPE" = "Darwin" ]; then
  if [ "$ARCH" = "arm64" ]; then
    DOWNLOAD_URL="https://downloads.limacharlie.io/sensor/mac/arm64"
  else
    DOWNLOAD_URL="https://downloads.limacharlie.io/sensor/mac/64"
  fi
else
  DOWNLOAD_URL="https://downloads.limacharlie.io/sensor/linux/64"
fi
curl -sSL "$DOWNLOAD_URL" -o "$TEMP_DIR/lc_sensor"
chmod +x "$TEMP_DIR/lc_sensor"

if [ "$OS_TYPE" = "Darwin" ]; then
  sudo nohup "$TEMP_DIR/lc_sensor" -d "abc123:def456:..." > /dev/null 2>&1 &
else
  sudo setsid "$TEMP_DIR/lc_sensor" -d "abc123:def456:..." > /dev/null 2>&1 &
fi
echo "Sensor started in $TEMP_DIR"

6. Verify sensor connection using a selector with the installation key's iid:

limacharlie sensor list --selector "iid == \`<IID_FROM_INSTALLATION_KEY>\`" --oid abc123-def456-... --output yaml

7. Inform user the sensor is running and how to stop it (using sudo pkill -f lc_sensor).

Example 2: Stopping the Test EDR

User: "Stop the test EDR"

Steps:

1. Stop sensor and clean up (single command):

sudo pkill -9 -f lc_sensor; sudo rm -rf /tmp/lc-edr-test-XXXXXX; echo "Cleanup complete"

2. Verify cleanup:

ps aux | grep "[l]c_sensor" || echo "Sensor stopped"

3. Optionally, delete the sensor from LimaCharlie:

limacharlie sensor delete --sid <SENSOR_ID> --confirm --oid abc123-def456-...

Additional Notes

• Cross-platform support: Works on Linux (x64), Mac OS Intel (x64), and Mac OS Apple Silicon (arm64)
• Root privileges required: The sensor needs sudo/root to properly monitor system calls, processes, files, and network activity
• Mac OS permissions: On Mac OS, the sensor may require granting permissions in System Preferences > Privacy & Security (Full Disk Access, Input Monitoring) for full functionality
• Temp directory: The sensor creates working files, so we use a dedicated temp directory to keep things clean
• Automatic tags: Sensors enrolled with this key get test-edr and temporary tags for easy identification
• Console visibility: The sensor appears in your LimaCharlie web console at https://app.limacharlie.io
• Background execution: The sensor runs in background, so you can continue working while it monitors
• Reusable key: The "Test EDR" installation key is reused if it already exists, avoiding duplicate keys
• Cleanup: Always clean up when done to avoid orphaned processes and files. Use ; not && when chaining cleanup commands since pkill returns non-zero exit codes even on success

Related Skills

• detection-engineering: For creating D&R rules to test with the sensor
• sensor-health: To check if your test sensor is reporting properly
• case-investigation: To investigate events from your test sensor