traceroute command

traceroute - trace the route to a host

The traceroute command in Linux is a network diagnostic tool used to trace the route packets take from your system to a destination host. It shows each hop (intermediate router or server) along the path, helping you identify network issues like delays or failures.

Note: traceroute may not be installed by default on some systems (e.g., Ubuntu). Install it with sudo apt install traceroute or use tracepath as an alternative.

Usage: traceroute [option ...] host [packet_size]

• host: The destination (e.g., google.com, 192.168.1.1).
• packet_size: Optional size of probe packets (in bytes).
• options: Flags to modify behavior.

Examples

• Basic Usage

  Run traceroute with a destination to see the path packets take.

  traceroute google.com
  • Output (example):

    traceroute to google.com (142.250.190.78), 30 hops max, 60 byte packets
    1  192.168.1.1 (192.168.1.1)  2.345 ms  2.567 ms  2.789 ms
    2  10.0.0.1 (10.0.0.1)  5.123 ms  5.456 ms  5.789 ms
    3  isp-gateway (203.0.113.1)  10.234 ms  10.567 ms  10.890 ms
    4  * * *
    5  google-edge (142.250.190.78)  15.678 ms  15.901 ms  16.123 ms
  • Explanation:
    • 1, 2, 3...: Hop number (each router or gateway).
    • IP (name): Address and hostname of the hop.
    • ms: Round-trip time for three probes per hop.
    • * * *: No response (timeout or blocked).

• Limiting Hops

  Use -m to set the maximum number of hops.

  traceroute -m 10 google.com
  • Stops after 10 hops (default is 30).

• Specifying Probes

  Use -q to set the number of probes per hop (default is 3).

  traceroute -q 1 google.com
  • Output shows only one time per hop:

    1  192.168.1.1 (192.168.1.1)  2.345 ms
    2  10.0.0.1 (10.0.0.1)  5.123 ms

• Using IP Only

  Use -n to skip hostname resolution (faster).

  traceroute -n google.com
  • Output:

    1  192.168.1.1  2.345 ms  2.567 ms  2.789 ms
    2  10.0.0.1    5.123 ms  5.456 ms  5.789 ms
  • Shows IPs without resolving to names.

• Setting Packet Size

  Specify packet size (in bytes) to test network behavior.

  traceroute google.com 100
  • Uses 100-byte packets instead of the default (60).

• Changing Protocol

  By default, traceroute uses UDP. Use -I for ICMP (like ping).

  traceroute -I google.com
  • Sends ICMP echo requests instead of UDP packets.

To get help related to the traceroute command use --help option

$ traceroute --help
Usage: traceroute [OPTION...] HOST
Print the route packets trace to network host.

  -f, --first-hop=NUM        set initial hop distance, i.e., time-to-live
  -g, --gateways=GATES       list of gateways for loose source routing
  -I, --icmp                 use ICMP ECHO as probe
  -m, --max-hop=NUM          set maximal hop count (default: 64)
  -M, --type=METHOD          use METHOD (`icmp' or `udp') for traceroute
                             operations, defaulting to `udp'
  -p, --port=PORT            use destination PORT port (default: 33434)
  -q, --tries=NUM            send NUM probe packets per hop (default: 3)
      --resolve-hostnames    resolve hostnames
  -t, --tos=NUM              set type of service (TOS) to NUM
  -w, --wait=NUM             wait NUM seconds for response (default: 3)
  -?, --help                 give this help list
      --usage                give a short usage message
  -V, --version              print program version

Mandatory or optional arguments to long options are also mandatory or optional
for any corresponding short options.

For more details, check the manual with man traceroute