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My name is Solène Rapenne. I like to learn and share my knowledge with other. With this blog I can share my experiences and issues. Some of my interests : '(BSD OpenBSD h+ Lisp Emacs cli-tool gaming internet-infrastructure Crossbow). I love % and lambda characters. OpenBSD Developer solene@.

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Port of the week : dnstop

Written by Solène, on 18 April 2018.
Tags: #unix

Dnstop is an interactive console application to watch in realtime the DNS queries going through a network interface. It currently only supports UDP DNS requests, the man page says that TCP isn’t supported.

It has a lot of parameters and keybinding for the interactive use

To install it on OpenBSD: doas pkg_add dnstop

We will start dnstop on the wifi interface using a depth of 4 for the domain names: as root type dnstop -l 4 iwm0 and then press ‘3’ to display up to 3 sublevel, the -l 4 parameter means we want to know domains with a depth of 4, it means that if a request for the domain my.very.little.fqdn.com. happens, it will be truncated as very.little.fqdn.com. If you press ‘2’ in the interactive display, the earlier name will be counted in the line fqdn.com’.

Example of output:

Queries: 0 new, 6 total                           Tue Apr 17 07:17:25 2018

Query Name          Count      %   cum%
--------------- --------- ------ ------
perso.pw                3   50.0   50.0
foo.bar                 1   16.7   66.7
hello.mydns.com         1   16.7   83.3
mydns.com.lan           1   16.7  100.0

If you want to use it, read the man page first, it has a lot of parameters and can filters using specific expressions.