sonar(6) XScreenSaver manual sonar(6)

sonar - display a sonar scope

sonar [-ping hosts-or-subnets] [-ping-timeout int] [-delay usecs] [-speed ratio] [-sweep-size ratio] [-font-size points] [-team-a-name string] [-team-b-name string] [-team-a-count int] [-team-b-count int] [-no-dns] [-no-times] [-no-wobble] [-debug] [-fps]

This draws a sonar screen that pings (get it?) the hosts on your local network, and plots their distance (response time) from you. The three rings represent ping times of approximately 2.5, 70 and 2,000 milliseconds respectively.

Alternately, it can run a simulation that doesn't involve hosts.

sonar understands the following options:

The list of things to ping, separated by commas or spaces. Elements of this list may be:
Run in simulation mode instead of pinging real hosts.
Ping the given host.
Ping the given IPv4 address.
Ping the local subnet. On systems where we can determine the local network mask, we use that; otherwise, we assume Class C (254 hosts).
Ping a different-sized local subnet: e.g., subnet/28 would ping a 4-bit subnet (the nearest 14 addresses). On systems where we can determine the local network mask, we always use that.
Ping an arbitrary other IPv4 subnet. The address specifies the base address, and the part after the slash is how wide the subnet is. Typical values are /24 (for 254 addresses) and /28 (for 14 addresses).
Ping the hosts listed in the given file. This file can be in the format used by /etc/hosts, or it can be any file that has host names as the first or second element on each line. If you use ssh, try this:


sonar -ping $HOME/.ssh/known_hosts

The amount of time in milliseconds the program will wait for an answer to a ping.
Delay between frames, in microseconds. Default 20000.
Less than 1 for slower, greater than 1 for faster. Default 1.
How big the glowing sweep area should be. Default 0.3.
How large the text should be. Default 10 points.
Keep the display stationary instead of very slowly wobbling back and forth.
Do not attempt to resolve IP addresses to hostnames.
Do not display ping times beneath the host names.
In simulation mode, the name of team A.
In simulation mode, the name of team B.
In simulation mode, the number of bogies on team A.
In simulation mode, the number of bogies on team B.
Display the current frame rate, polygon count, and CPU load.

In ping-mode, the display is a logarithmic scale, calibrated so that the three rings represent ping times of approximately 2.5, 70 and 2,000 milliseconds respectively.

This means that if any the hosts you are pinging take longer than 2 seconds to respond, they won't show up; and if you are pinging several hosts with very fast response times, they will all appear close to the center of the screen (making their names hard to read.)

For this program to be able to ping other hosts, it must have the ability to open ICMP sockets, which is usually an action that requires additional privileges.

If your system has setcap(8) then this permission can be added with

setcap cap_net_raw=p sonar
Otherwise, the program must be setuid root in order to ping hosts. Privileges are disavowed shortly after startup (just after connecting to the X server) so this is believed to be safe:
chown root:root sonar
chmod u+s sonar

It is not necessary to use setcap or setuid on macOS systems, as unprivileged programs can ping by using ICMP DGRAM sockets instead of ICMP RAW.

Does not support IPv6.

X(1), xscreensaver(1), ping(8), ping6(8)

Copyright © 2000-2021 by Jamie Zawinski <jwz@jwz.org>
Copyright © 1998 by Stephen Martin. <smartin@canada.com>

Permission to use, copy, modify, distribute, and sell this software and its documentation for any purpose is hereby granted without fee, provided that the above copyright notice appear in all copies and that both that copyright notice and this permission notice appear in supporting documentation. No representations are made about the suitability of this software for any purpose. It is provided "as is" without express or implied warranty.

Stephen Martin <smartin@canada.com>, 3-nov-1998.

Subnet support, etc. added by Jamie Zawinski, 17-Jul-2000.

Rewritten using OpenGL instead of X11 by Jamie Zawinski, 12-Aug-2008.

6.02 (11-Oct-2021) X Version 11