mtr

Continuous path diagnostics combining ping and traceroute. Shows latency and packet loss per hop over time.

Category: Networking / Diagnostics Path Quality Latency Packet Loss Interactive

What it does

mtr (My Traceroute) continuously probes the network path to a destination, combining the hop discovery of traceroute with the ongoing latency and loss measurements of ping.

How it works (mechanical)

mtr sends probe packets with increasing TTL values to discover each hop. Unlike traceroute, it keeps sending probes, maintaining rolling statistics (loss, latency, jitter) for every hop in the path.

  • TTL-based hop discovery
  • Repeated probes per hop
  • Rolling statistics over time
  • ICMP, UDP, or TCP probes (depending on options)

10 Practical Examples

# 1) Interactive trace to a host
mtr example.com
# 2) Numeric output only (no DNS)
mtr -n example.com
# 3) Report mode (one-shot summary)
mtr -r example.com
# 4) Report mode with 100 probes
mtr -r -c 100 example.com
# 5) TCP-based probes (firewall-friendly)
mtr -T example.com
# 6) Use a specific port for TCP probes
mtr -T -P 443 example.com
# 7) Wide output (better alignment)
mtr -w example.com
# 8) IPv6 path testing
mtr -6 ipv6.google.com
# 9) JSON output (automation)
mtr -r -j example.com
# 10) Diagnose intermittent packet loss
mtr -n -c 200 example.com

Notes & Gotchas

  • Loss shown at intermediate hops may be ICMP rate-limiting.
  • End-to-end loss is the most important metric.
  • TCP mode often succeeds where ICMP is blocked.
  • Interactive mode is best for live diagnosis.
  • Report mode is ideal for sharing with providers.

Historical Context

mtr was created to overcome the snapshot nature of traceroute, giving operators a live, statistical view of path quality rather than a single moment in time.

Modern Equivalent / Related Tools

  • traceroute — single-pass hop discovery
  • tracepath — MTU-focused path tracing
  • ping — reachability and latency
  • smokeping — long-term latency monitoring
  • tcpdump — packet-level confirmation