dumpaxfr.1

.Dd December 5, 2024
.Dt DUMPAXFR 1 "DNS Commands Manual"
.Os DNS
.Sh NAME
.Nm dumpaxfr
.Nd capture a DNS zone transfer
.Sh SYNOPSIS
.Nm
.Op Fl 46dxV
.Op Fl p Ar port
.Aq Ar server
.Aq Ar zone
.Op Ar prefix
.Sh DESCRIPTION
The
.Nm
program
sends a DNS AXFR zone transfer query to
.Ar server
for
.Ar zone
and saves the response in one or more files.
The files are named like
.Sm off
.D1 Ar prefix Li _ Ar server Li _ Ar zone Li _ Va N Li .bin
.Sm on
.Pp
You specify the
.Ar server ,
.Ar zone ,
and
.Ar prefix
on the command line.
The default
.Ar prefix
is
.Li xfer .
.Pp
A zone transfer can consist of multiple DNS messages.
Each message is written to a different file numbered
.Va N
starting from 0.
.Pp
The
.Li .bin
suffix indicates that the file is a binary dump.
.Sh OPTIONS
.Bl -tag -width indent
.It Fl 4
Use IPv4 only.
.It Fl 6
Use IPv6 only.
.It Fl d
Print query and responses in a similar manner to
.Xr dig 1 .
.It Fl x
Print partially-parsed hex dump of responses.
.It Fl p Ar port
Connect to
.Ar port ,
which may be a service name or a port number.
The default is the
.Sy domain
service, port 53.
.It Fl V
Print details about this version of
.Nm .
.El
.Sh BUGS
The
.Nm
program incorrectly uses a
.Fn read
timeout to detect the end of the zone transfer;
it always finishes by reporting an error.
The DNS protocol indicates the end of a zone transfer
with a message whose last record is a second copy of the zone's SOA record.
The
.Nm
program does not parse responses
(except when printing decoded messages)
so it is too stupid to detect the end of the zone transfer correctly.
.Sh SEE ALSO
.Xr dig 1
.Sh AUTHOR
.An Tony Finch
.Aq Li dot@dotat.at
.\" SPDX-License-Identifier: 0BSD OR MIT-0