Ping with estimated distance based on the speed of light ... because why not ? :D
The shell script ping2km is a humorous tool that runs a continuous ping to a host and estimates the "as the fibre flies" distance based on the Round Trip Time (RTT).
Four transmission models are available :
| Mode | Speed | Factor | Formula |
|---|---|---|---|
--fiber (default) |
2/3 c ≈ 199,861 km/s | 99.9305 | distance = RTT_ms × 99.9305 km |
--copper |
2/3 c ≈ 197,863 km/s | 98.93 | distance = RTT_ms × 98.93 km |
--theoretical |
c ≈ 299,792 km/s | 149.896 | distance = RTT_ms × 149.896 km |
--dialup |
2/3 c minus modem | 99.9305 | distance = (RTT_ms - 120) × 99.9305 km |
Since the RTT (Round Trip Time) is a round trip, the estimated distance is :
distance = (RTT_ms / 1000 / 2) × speed
The fiber model uses the real speed of light in optical fibre (~2/3 of c, due to the refractive index of silica glass).
The copper model uses the real propagation speed in telephone twisted pair cables (~2/3 of c, due to the dielectric properties of the insulation). Plot twist: fiber and copper give nearly identical results (~1% difference). The signal travels at roughly the same speed in both media. The real difference between fiber and copper has never been propagation speed — it's bandwidth (data throughput) and attenuation (signal loss over distance).
The theoretical model uses c, the speed of light in vacuum (299,792 km/s). This is the absolute physical limit, achievable only in a perfect vacuum. In reality, no transmission medium reaches c. But where's the fun in reality?
The dialup model simulates the good old RTC (Public Switched Telephone Network) era. Analog modems added approximately 120 ms of round-trip latency just for signal encoding/decoding (modulation/demodulation — that's what "modem" stands for). This overhead is subtracted from the RTT before calculating the distance. Back in the dial-up days, the world was smaller. If the RTT is less than 120 ms, the distance shows 0 km [too close for dial-up].
This is intentionally naive. The estimation does not account for :
- Router/switch/firewall processing latency
- Network topology detours
- Buffering and queuing delays
- Application-level processing
- etc.
The actual distance traveled by packets is always greater than the geographical distance, which means that Berlin may be closer to you than New York.
This tool is meant for fun between friends, not for calibrating interferometers ;-)
curl -O https://raw.githubusercontent.com/deuza/ping2km/main/ping2km.sh
mv ping2km.sh ping2km
chmod +x ping2km
sudo cp ping2km /usr/local/bin/If curl is not available, you can use another tool such as wget to retrieve the script directly.
wget https://raw.githubusercontent.com/deuza/ping2km/main/ping2km.shStandard POSIX utilities, nothing exotic :
pinggrepsedbcprintf
On Debian/Ubuntu, bc might need to be installed : apt install bc
ping2km [--fiber|--copper|--theoretical|--dialup] [-4] [-c count] <host>
ping2km --help
ping2km --version
Hit Ctrl+C to stop, a statistics summary will be displayed, including RTT and estimated distance (min/avg/max).
Tested on :
- Debian GNU/Linux 12.x / 13.x (arm64/amd64)
- FreeBSD 13.x / 14.x
- macOS (Darwin) Ventura, Sonoma, Sequoia (arm64)
The script uses strictly POSIX sed, POSIX shell arithmetic $((...)), and bc for floating point, just KISS.
Ping a hostname (fiber, default) :
$ ping2km www.deuza.net
Send only 5 packets :
$ ping2km -c 5 www.deuza.net
Ping with copper model (spoiler: same result as fiber, troll mode :P) :
$ ping2km --copper www.deuza.net
Ping with theoretical speed of light in vacuum :
$ ping2km --theoretical 1.1.1.1
Ping like it's 1998 :
$ ping2km --dialup www.kernel.org
Force IPv4 :
$ ping2km -4 www.deuza.net
Combine options :
$ ping2km --dialup -4 -c 10 www.kernel.org
Unknown host:
$ ping2km nope.invalid
ping2km: nope.invalid: Name or service not known
This script was created around 2002 on Solaris/FreeBSD at Club-Internet on 36 lines.
It was revived, corrected, made portable, and properly documented in March 2026.
CC0 1.0 Universal -- Public Domain.
WTFPL -- Do What the Fuck You Want to Public License.
Nothing planned
The output is designed to mimic standard ping(8) output as closely as possible, with the distance appended to each line.
Should not work under Solaris and with exotic ping outputs.
The output line that is parsed should look like this:
$ ping www.deuza.net
PING www.deuza.net (66.6.44.4) 56(84) bytes of data.
64 bytes from 66.6.44.4: icmp_seq=1 ttl=52 time=92.8 ms
64 bytes from 66.6.44.4: icmp_seq=2 ttl=52 time=96.1 ms
^C
--- www.deuza.net ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 1001ms
rtt min/avg/max/mdev = 92.836/94.470/96.105/1.634 ms
root@pi5:~#
With ❤️ by DeuZa