What it does¶

The route tool performs traceroute to visualize the network path between your device and a destination. Each hop shows:

• Hop number (TTL / time-to-live)
• IP address of the intermediate router
• Reverse-DNS hostname (if available)
• Round-trip time (RTT) — latency from you to that hop
• ASN (Autonomous System Number) — the network operator at that hop
• AS Name — the organization name of that network

You can also compare routes over time to detect changes in your network path — useful for spotting failovers, load balancer rotations, or ISP route changes.

Quick start¶

Basic traceroute¶

netglance route trace google.com

Shows the path to google.com with ASN information for each hop.

Save and compare routes¶

netglance route trace google.com --save
# ... later ...
netglance route trace google.com --save --diff

Compare the current path against the last saved route. Detects hop changes, new ASNs, and path length differences.

Adjust probe parameters¶

netglance route trace 8.8.8.8 --max-hops 20 --timeout 3.0

Reduce maximum hops to speed up the trace, or increase timeout if hops are slow to respond.

Commands¶

netglance route trace¶

Run a traceroute to a destination.

Arguments: - HOST — Target hostname or IP address (required)

Options: - --max-hops, -m — Maximum number of hops to probe (default: 30) - --timeout, -t — Timeout per probe in seconds (default: 2.0) - --save — Persist results to SQLite for future comparison - --diff — Compare this route against the last saved route (only works if you've previously used --save)

Examples:

# Trace to a hostname
netglance route trace example.com

# Trace with 20 hops max and 3-second timeout
netglance route trace 1.1.1.1 --max-hops 20 --timeout 3.0

# Save for later comparison
netglance route trace aws.amazon.com --save

# Show changes from last saved route
netglance route trace aws.amazon.com --save --diff

Understanding the output¶

The trace table¶

Each row represents a hop (intermediate router) on the path:

Status line¶

Below the table: - Reached (green) — You successfully reached the destination IP - Not reached (red) — The destination was not found in the trace

Route changes (with --diff)¶

When comparing against a saved route, you'll see:

1. Route Changes table — Shows hop numbers and IP changes
2. Previous IP (red) — Old IP at that hop
3. Current IP (green) — New IP at that hop

4. If no table appears, the route hasn't changed

5. New ASNs observed — ASNs seen in the current route but not in the previous one

6. Path length delta — Whether the path is longer or shorter than before

Related concepts¶

• Ping — Measure latency to a single host. Use this when you just need RTT, not the full path.
• DNS — Resolve hostnames and check for DNS leaks. The route tool uses reverse-DNS on each hop.
• Autonomous Systems (ASN) — Every router belongs to an AS, identified by its ASN. Traceroute maps which organizations carry traffic to your destination.

Troubleshooting¶

Seeing * * * for many hops¶

Some routers are configured not to respond to traceroute probes (firewall rules or ICMP rate limiting). This shows as * * * in the RTT column.

Solution: This is normal. The trace continues to subsequent hops. If the destination is eventually reached, the path is intact.

Route keeps changing on every run¶

Load balancers, multipath routing, or traffic engineering can cause slight path variations between runs.

Solution: Use --save --diff on multiple consecutive runs. A genuine route change shows distinct hop IP changes. Natural variation affects only a hop or two.

Trace stops before reaching the destination¶

The destination may be: - Blocking ICMP (some firewalls) - Configured to not respond to traceroute at all - Unreachable from your network

Solution: Check with netglance ping <host> to verify the host is actually reachable. If it responds to ping but not traceroute, the destination blocks traceroute probes.

Asymmetric routing¶

Outbound path (you → destination) differs from return path (destination → you). You see the outbound hops in traceroute, not the return path.

Solution: This is normal on the internet. AS owners often optimize egress and ingress paths separately. If you need to see the return path, use a tool on the destination end.

Needs elevated privileges¶

On some systems, raw socket traceroute requires root or administrator access.

Solution: Run with sudo:

sudo uv run netglance route trace example.com