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Ping

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Test host reachability and measure round-trip latency using ICMP echo requests.

What it does

The ping tool sends ICMP echo requests to hosts and measures how long each reply takes (round-trip time, or RTT). This is one of the quickest ways to verify that a host is reachable on your network and whether the connection quality is good or degraded.

netglance's ping subcommand group includes four modes:

  • host — Ping a specific IP or hostname.
  • gateway — Automatically detect and ping your default gateway (your router).
  • internet — Check connectivity to the public internet by pinging Cloudflare, Google, and Quad9 DNS servers.
  • sweep — Ping all hosts in a subnet and show which ones are alive (useful for a quick liveness check).

Each command can run once to get a snapshot, or continuously with --watch to see real-time changes.

Quick start

# Ping your gateway (router) once
netglance ping gateway

# Ping a specific host continuously (useful for debugging Wi-Fi issues)
netglance ping host 192.168.1.100 --watch

# Check if you have internet (pings public DNS servers)
netglance ping internet

# Sweep your local subnet for responsive hosts
netglance ping sweep 192.168.1.0/24

# Ping with custom echo count (default is 4)
netglance ping host 8.8.8.8 --count 10

Commands

ping host — Ping a single host

netglance ping host <HOST> [OPTIONS]

Arguments: - HOST — IP address or hostname to ping (required).

Options: - --count, -c <N> — Number of ICMP echo requests to send. Default: 4. - --timeout, -t <SECONDS> — Timeout (seconds) to wait for each reply. Default: 2.0. - --watch, -w — Continuous ping with live updating display. Press Ctrl+C to stop.

ping gateway — Ping the default gateway

netglance ping gateway [OPTIONS]

Automatically detects your default gateway (typically your router) and pings it.

Options: - --count, -c <N> — Number of ICMP echo requests. Default: 4. - --timeout, -t <SECONDS> — Timeout (seconds) per request. Default: 2.0. - --watch, -w — Continuous ping with live display.

ping internet — Check internet connectivity

netglance ping internet [OPTIONS]

Pings three well-known public DNS servers (Cloudflare, Google, Quad9) to verify you can reach the public internet. This is a quick sanity check for outbound connectivity.

Options: - --count, -c <N> — Number of echo requests per host. Default: 4. - --timeout, -t <SECONDS> — Timeout (seconds) per request. Default: 2.0. - --watch, -w — Continuous check with live display.

ping sweep — Sweep a subnet for responsive hosts

netglance ping sweep <SUBNET> [OPTIONS]

Arguments: - SUBNET — CIDR subnet to scan (e.g., 192.168.1.0/24). Required.

Options: - --timeout, -t <SECONDS> — Timeout (seconds) per host. Default: 1.0.

The output shows only the hosts that replied (are alive). This is faster than ARP discovery for a quick liveness check but may miss some devices (e.g., those behind firewalls that block ICMP).

Understanding the output

Each command displays a table with these columns:

Column Meaning
Host IP address or hostname that was pinged.
Status UP (green) if reachable, DOWN (red) if no response.
Avg Average round-trip time in milliseconds. -- if host is unreachable.
Min Fastest reply time.
Max Slowest reply time.
Loss Percentage of packets that did not receive a reply (0–100%).

Interpreting latency

The color of the latency values indicates quality:

  • Green (< 20 ms) — Excellent latency. Typical for local network hosts or geographically close servers.
  • Yellow (20–100 ms) — Good latency. Normal for distant servers or high-latency links.
  • Red (≥ 100 ms) — Poor latency. May indicate network congestion, Wi-Fi interference, or a slow internet connection.

Gateway latency guidelines

  • < 5 ms — Excellent. You are wired and very close to the gateway.
  • 5–20 ms — Normal. Typical for Wi-Fi or a slightly longer local path.
  • > 50 ms — Investigate. May indicate congestion, interference, or a broken route.

Internet latency guidelines

  • < 50 ms — Good. Responsive and snappy.
  • 50–150 ms — Acceptable. Noticeable but usable for most tasks.
  • > 200 ms — Slow. May affect real-time applications (VoIP, gaming) or feel sluggish.

Sweep mode

The ping sweep command pings every IP on a subnet and reports only the alive hosts. By default, timeout is shorter (1 second) to keep the sweep fast.

netglance ping sweep 192.168.1.0/24

This is useful for: - Quick inventory of active devices on your network. - Detecting when new devices join or go offline. - Baseline before more invasive discovery (e.g., ARP or nmap).

Note: ICMP may be filtered by individual firewalls, so a host showing as DOWN does not always mean it is offline—it may simply be blocking ICMP. Use ARP discovery or device-specific checks for more reliable detection.

  • How Networks Work — Background on ICMP, gateways, and network hops.
  • Discovery — ARP and mDNS discovery for a more comprehensive device inventory.
  • Network Baseline — Take snapshots of network state and compare over time.

Troubleshooting

Host shows as DOWN but I know it's online

Cause: The host is blocking ICMP echo requests via a local firewall or upstream firewall rules.

Solutions: - Try pinging from a different network to rule out upstream filters. - Use ARP discovery (netglance discover arp) instead; it doesn't rely on ICMP. - Check if the host has a firewall rule blocking ICMP (e.g., Windows Defender, iptables).

"Could not detect default gateway" error

Cause: The system could not automatically find the default gateway.

Solutions: - Ensure you have an active network connection. - On Linux, verify that /proc/net/route exists and is readable. - On macOS/BSD, verify that the route command is available. - Manually specify the gateway IP: netglance ping host <GATEWAY_IP>.

High packet loss or inconsistent latency

Causes: - Network congestion (saturated link). - Wi-Fi interference (other networks on the same channel, microwave ovens, cordless phones). - Routing instability or link flapping. - Host under load, slow to respond.

Solutions: - Use --watch to observe latency over time and spot trends. - Check for Wi-Fi interference with the wifi module (netglance wifi scan). - Look for traffic spikes with the traffic module. - Move closer to the access point if on Wi-Fi. - Restart the gateway or affected host.

Elevated privileges required (Linux)

Some systems require sudo to send raw ICMP packets. netglance attempts to use unprivileged ping, but if you see permission errors:

sudo netglance ping gateway

On modern Linux systems with CAP_NET_RAW, unprivileged ping usually works out of the box.

Timeout too short or too long

If most replies arrive with "timeout" or --, adjust the --timeout flag:

  • Increase (--timeout 5.0) if the host is slow or the network is congested.
  • Decrease (--timeout 0.5) if you want faster failures and the host is known to be fast.

Default is 2 seconds, which works for most local and internet hosts.

Baseline Speed