dnstop(8) - Linux man page

Name

dnstop - displays various tables of DNS traffic on your network

Synopsis

dnstop [-46apsQR] [-b expression] [-i address] [-f filter] [-r interval] [device] [savefile]

Description

dnstop is a small tool to listen on device or to parse the file savefile and collect and print statistics on the local network's DNS traffic. You must have read access to /dev/bpf*.

Command Line Options

The options are as follows:

      -4'        count only messages with IPv4 addresses

-6' count only messages with IPv6 addresses

-a' anonymize addresses

-b expression
BPF filter expression
(default: udp port 53)

-i address
ignore select addresses

-p' Do not put the interface into promiscuous mode.

-r' Redraw interval (seconds).

-l level
keep counts on names up to level domain name levels.

For example, with -l 2 (the default), dnstop will keep two tables: one with top-level domain names, and another with second-level domain names. Increasing the level provides more details, but also requires more memory and CPU.

-f' input filter name

The "unknown-tlds" filter includes only queries for TLDs that are bogus. Useful for identifying hosts/servers that leak queries for things like "localhost" or "workgroup."

The "A-for-A" filter includes only A queries for names that are already IP addresses. Certain Microsoft Windows DNS servers have a known bug that forward these queries.

The "rfc1918-ptr" filter includes only PTR queries for addresses in RFC1918 space. These should never leak from inside an organization.

-Q' count only DNS query messages

-R' count only DNS reply messages

savefile
a captured network trace in pcap format

device
ethernet device (ie fxp0)

Run Time Options

While running, the following options are available to alter the display:

s'        display the source address table

d' display the destination address table

t' display the breakdown of query types seen

o' display the breakdown of opcodes seen

1' show 1st level query names

2' show 2nd level query names

3' show 3rd level query names

4' show 4th level query names

5' show 5th level query names

6' show 6th level query names

7' show 7th level query names

8' show 8th level query names

9' show 9th level query names

!' show sources + 1st level query names

@' show sources + 2nd level query names

#' show sources + 3rd level query names

$' show sources + 4th level query names

%' show sources + 5th level query names

^' show sources + 6th level query names

&' show sources + 7th level query names

*' show sources + 8th level query names

(' show sources + 9th level query names

^R' reset the counters

^X' exit the program

space
redraw

?' help

NON-INTERACTIVE MODE

If stdout is not a tty, dnstop runs in non-interactive mode. In this case, you must supply a savefile for reading, instead of capturing live packets. After reading the entire savefile, dnstop prints the top 50 entries for each table.

Authors

       Duane Wessels (wessels@measurement-factory.com)

Mark Foster (mark@foster.cc)
Jose Nazario (jose@monkey.org)
Sam Norris <@ChangeIP.com>
Max Horn <@quendi.de>
John Morrissey <jwm@horde.net>
Florian Forster <octo@verplant.org>
Dave Plonka <plonka@cs.wisc.edu>
http://dnstop.measurement-factory.com/

Bugs

BSD 21 March, 2008 BSD