**License: Pro** - Requires a Pro or Enterprise license.

Ping Gateway Probe#

The Ping Gateway probe monitors network connectivity to the default gateway or a specified IP address, providing essential metrics for detecting network routing issues, ISP quality problems, and local network connectivity.

Quick Start#

Basic Configuration#

probes:
  - name: ping_gateway
    params:
      interval: 30  # Collection interval in seconds (default: 30)

Minimal Configuration#

probes:
  - name: ping_gateway
    params: {}

The Ping Gateway probe requires no mandatory parameters and automatically detects the default gateway. It works out-of-the-box with default settings.

Supported Platforms#

• Windows: Windows Server 2012+ / Windows 10+
• Linux: All modern distributions (Ubuntu, RHEL, CentOS, Debian, etc.)
• macOS: macOS 10.13+

Platform-specific ping implementations are automatically selected based on the operating system.

Key Metrics Summary#

Configuration Parameters#

Example Configurations#

High-frequency monitoring (every 10 seconds):

probes:
  - name: ping_gateway
    params:
      interval: 10

Standard monitoring (every minute):

probes:
  - name: ping_gateway
    params:
      interval: 60

Low-frequency monitoring (every 5 minutes):

probes:
  - name: ping_gateway
    params:
      interval: 300

How It Works#

Gateway Auto-Detection#

The probe automatically detects the default gateway by:

1. Enumerating network interfaces - Identifies all active, non-loopback interfaces
2. Selecting primary interface - Chooses the first interface with an IPv4 address
3. Extracting gateway IP - Uses the interface’s network configuration

Note: The current implementation returns the local interface IP, not the actual gateway. This is a known limitation that will be addressed in future versions.

Ping Collection Process#

The probe sends 10 ICMP echo requests to the target IP and collects:

• Average latency: Mean round-trip time across all successful pings
• Packet loss: Percentage of packets that did not receive a reply

Platform-Specific Implementations:

• Windows: Uses ping -n 10 <ip> command
• Linux: Uses ping -c 10 <ip> command
• macOS: Uses ping -c 10 <ip> command

All implementations parse the native ping command output to extract metrics.

Monitoring Tool Integration#

PRTG Network Monitor#

Access gateway metrics in PRTG JSON format:

# All gateway metrics
curl http://localhost:8080/api/{agentkey}/prtg/metrics

# Configure PRTG HTTP Advanced Sensor:
# - URL: http://agent-host:8080/api/{agentkey}/prtg/metrics
# - Method: POST
# - Request body: {"probe": "ping_gateway"}

PRTG Channels Available:

• Gateway Average Latency (ms)
• Gateway Packet Loss (%)

Recommended Limits:

{
  "Gateway Average Latency": {
    "LimitMaxWarning": 50,
    "LimitMaxError": 100,
    "LimitMode": 1
  },
  "Gateway Packet Loss": {
    "LimitMaxWarning": 1,
    "LimitMaxError": 5,
    "LimitMode": 1
  }
}

Nagios/Icinga#

Access gateway metrics in Nagios format:

# All gateway metrics with performance data
curl http://localhost:8080/api/{agentkey}/nagios/metrics?probe=ping_gateway

# Example output:
# OK - Gateway connectivity normal | averageLatency=15.3ms;50;100 packetLoss=0.0%;1;5

Nagios Performance Data:

• averageLatency - Gateway latency with 50ms warning, 100ms critical
• packetLoss - Packet loss with 1% warning, 5% critical

Service Check Configuration:

define service {
    use                     generic-service
    host_name               monitored-server
    service_description     Gateway Connectivity
    check_command           check_http_json!8080!/api/{agentkey}/nagios/metrics?probe=ping_gateway
    check_interval          1
    retry_interval          1
    max_check_attempts      3
}

Grafana/Prometheus#

Access metrics in Prometheus-compatible format:

# Prometheus format
curl http://localhost:8080/api/{agentkey}/prometheus/metrics

# Example output:
# ping_gateway_average_latency{hostname="server01"} 15.3
# ping_gateway_packet_loss{hostname="server01"} 0.0

Grafana Dashboard Queries:

# Gateway latency over time
ping_gateway_average_latency{hostname="server01"}

# Packet loss percentage
ping_gateway_packet_loss{hostname="server01"}

# Latency rate of change (detect spikes)
rate(ping_gateway_average_latency{hostname="server01"}[5m])

Alert Rules:

groups:
  - name: gateway_connectivity
    rules:
      - alert: HighGatewayLatency
        expr: ping_gateway_average_latency > 50
        for: 5m
        annotations:
          summary: "High gateway latency on {{ $labels.hostname }}"
          description: "Gateway latency is {{ $value }}ms (threshold: 50ms)"

      - alert: GatewayPacketLoss
        expr: ping_gateway_packet_loss > 1
        for: 2m
        annotations:
          summary: "Gateway packet loss detected on {{ $labels.hostname }}"
          description: "Packet loss is {{ $value }}% (threshold: 1%)"

Web Interface#

View gateway metrics in the built-in dashboard:

http://localhost:8080/web/{agentkey}/dashboard

Features:

• Real-time latency visualization
• Packet loss monitoring
• Historical trend graphs
• Network connectivity status

Use Cases#

Network Connectivity Monitoring#

Monitor local network connectivity to detect:

• Gateway failures: Complete loss of connectivity to the default gateway
• Network path issues: Routing problems between host and gateway
• Local switch problems: Layer 2 connectivity issues

Typical Alert Configuration:

• Packet loss > 1%: Warning (investigate network)
• Packet loss > 5%: Critical (network failure)

ISP Quality Monitoring#

Track Internet Service Provider quality:

• Latency increases: Detect congestion or routing changes
• Packet loss patterns: Identify intermittent connectivity issues
• Performance degradation: Monitor for ISP throttling or oversubscription

Use with WebApp Probe: Combine gateway ping with external website monitoring to isolate local vs. WAN issues.

Routing Issues Detection#

Identify routing problems:

• Gateway unreachable: Local network configuration issues
• High latency: Network congestion or misconfigured routes
• Intermittent connectivity: Faulty network equipment

Correlation with Other Metrics:

• Compare with WebApp probe to distinguish local vs. remote issues
• Check network interface metrics for errors/collisions
• Review system logs for DHCP or routing updates

Network Troubleshooting#

Diagnose network issues:

• Baseline establishment: Normal latency and packet loss patterns
• Change detection: Identify when network performance degrades
• Isolation: Determine if issues are local (gateway) or remote (internet)

Troubleshooting Workflow:

1. Check gateway ping (this probe) - Is local network working?
2. Check external ping (webapp probe) - Is internet working?
3. Check interface metrics (network probe) - Are there errors?
4. Review system logs - Any configuration changes?

Troubleshooting#

No Metrics Collected#

Check probe status:

# View agent logs with gateway probe debugging
./agent run --authentication-key YOUR_KEY --verbose --debug-modules probe.gateway

Verify probe is enabled:

# Check configuration
cat agent-config.yaml | grep -A5 "name: ping_gateway"

Common Causes:

• Firewall blocking ICMP echo requests
• Network interface disabled or misconfigured
• Gateway auto-detection failure (no active interfaces)

Gateway Detection Failed#

Symptom: Error message “no default gateway found”

Solution:

Windows:

# Verify network configuration
ipconfig /all

# Check routing table
route print

# Verify default gateway
netstat -rn | findstr "0.0.0.0"

Linux:

# Check network interfaces
ip addr show

# Check routing table
ip route show

# Verify default gateway
ip route | grep default

macOS:

# Check network interfaces
ifconfig

# Check routing table
netstat -rn | grep default

High Latency or Packet Loss#

Symptom: Consistently high latency (>50ms) or packet loss (>1%)

Diagnosis Steps:

1. Verify local network health:

   # Check interface errors (Linux)
   ip -s link
   
   # Check interface errors (Windows)
   netsh interface ipv4 show subinterfaces

2. Test connectivity directly:

   # Windows
   ping -n 20 <gateway-ip>
   
   # Linux/macOS
   ping -c 20 <gateway-ip>

3. Check for network congestion:

   • Review bandwidth utilization
   • Check for broadcast storms
   • Verify switch/router performance

4. Hardware issues:

   • Loose or damaged cables
   • Failing network interface card
   • Overheating network equipment

Mitigation:

• Replace faulty cables
• Update network drivers
• Restart network equipment
• Check for firmware updates

Firewall Blocking ICMP#

Symptom: 100% packet loss, but network appears to be working

Solution:

Windows Firewall:

# Allow ICMP Echo Request (outbound)
netsh advfirewall firewall add rule name="ICMP Allow outgoing V4 echo request" protocol=icmpv4:8,any dir=out action=allow

# Allow ICMP Echo Reply (inbound)
netsh advfirewall firewall add rule name="ICMP Allow incoming V4 echo reply" protocol=icmpv4:0,any dir=in action=allow

Linux iptables:

# Allow ICMP Echo Request (outbound)
sudo iptables -A OUTPUT -p icmp --icmp-type echo-request -j ACCEPT

# Allow ICMP Echo Reply (inbound)
sudo iptables -A INPUT -p icmp --icmp-type echo-reply -j ACCEPT

Linux firewalld:

# Allow ICMP permanently
sudo firewall-cmd --permanent --add-icmp-block-inversion
sudo firewall-cmd --reload

Permission Denied (Unix/Linux)#

Symptom: Error message “permission denied” when executing ping

Solution:

Most modern systems allow unprivileged users to ping, but if you encounter permission issues:

# Option 1: Run agent as root
sudo ./agent run --authentication-key YOUR_KEY

# Option 2: Grant ping capabilities (Linux)
sudo setcap cap_net_raw+ep /usr/bin/ping

# Option 3: Add agent user to netdev group (Debian/Ubuntu)
sudo usermod -a -G netdev senhub-agent

Inconsistent Results#

Symptom: Metrics vary significantly between collections

Explanation: Network conditions naturally fluctuate. Some variance is normal.

Acceptable Variance:

• Latency: +/-5-10ms is typical
• Packet loss: 0-1% is acceptable

Excessive Variance Indicators:

• Latency swings > 50ms
• Intermittent 100% packet loss
• Packet loss > 5% sustained

Investigation:

• Check for network congestion patterns
• Review network equipment logs
• Monitor bandwidth utilization
• Verify QoS configurations

Performance Considerations#

Collection Overhead#

The Ping Gateway probe has minimal overhead:

• Command execution: ~100-200ms per collection (10 pings)
• Parsing overhead: < 10ms
• Total collection time: ~200-300ms

Note: The ping command sends 10 ICMP packets with default timeout, which is generally sufficient for local gateway monitoring.

Network Impact#

Network impact is negligible:

• 10 ICMP packets per collection interval
• Packet size: 64 bytes (default ping size)
• Bandwidth: ~640 bytes every 30 seconds = ~170 bits/sec
• Total overhead: < 0.001% on 10 Mbps link

Recommended Intervals#

Recommendation for Most Environments: 30-60 seconds provides good balance between detection speed and system overhead.

Advanced Configuration#

Multiple Gateway Monitoring#

Monitor multiple gateways or network paths:

probes:
  - name: ping_gateway_primary
    params:
      interval: 30

  - name: ping_gateway_secondary
    params:
      interval: 60

Note: Current implementation auto-detects only the default gateway. Manual gateway specification will be supported in future versions.

Integration with Other Probes#

Comprehensive network monitoring setup:

probes:
  # Local network connectivity
  - name: ping_gateway
    params:
      interval: 30

  # External connectivity and DNS
  - name: ping_webapp
    params:
      interval: 60
      targets:
        - url: "https://www.google.com"
        - url: "https://1.1.1.1"

  # Interface metrics
  - name: network
    params:
      interval: 30

This combination provides:

• Gateway probe: Local network health (Layer 3)
• WebApp probe: Internet connectivity and latency
• Network probe: Interface errors, bandwidth, packet statistics

Known Limitations#

1. Gateway Detection: Currently returns the local interface IP instead of the actual gateway IP. This will be improved in future versions.

2. IPv6 Support: The probe currently focuses on IPv4 connectivity. IPv6 support is planned for future releases.

3. Manual Gateway Override: No option to specify a custom gateway IP. Auto-detection is the only supported mode.

4. Jitter Metrics: The probe does not currently calculate jitter (latency variance). This is planned for future releases.

Requirements#

Windows#

• Windows Server 2012+ or Windows 10+
• ping.exe command (built into Windows)
• ICMP outbound/inbound allowed in firewall

Linux/Unix/macOS#

• ping command installed (pre-installed on most systems)
• ICMP outbound/inbound allowed in firewall
• Network interface with IPv4 address configured

Network#

• Local network access to default gateway
• ICMP echo request/reply allowed (firewall/router)
• HTTP strategy required for remote access to metrics