Program: pydig (a DNS query tool written in Python)
Written by: Shumon Huque shuque@gmail.com
pydig is a program to perform DNS queries and exercise various existing and emerging features of the DNS protocol. It is roughly modelled after the dig program that comes with ISC BIND. I wrote it mostly for fun, and to help me learn learn some of the more esoteric features of the DNS. Occasionally I use it to quickly prototype new and proposed enhancements to the DNS. Some of the more recent such features include EDNS client subnet, chain query, cookies, DNS over TLS, EDNS padding, DNS over HTTPS, and more.
RR type and class codes (qtype and qclass) unknown to this program can be specified with the TYPE123 and CLASS123 syntax.
$ pydig -h
pydig (a DNS query tool written in Python), version 1.6.5
Usage: pydig [list of options] <qname> [<qtype>] [<qclass>]
pydig @server +walk <zone>
Options:
-h print program usage information
@server server to query
-pNN use port NN (default is port 53)
-bIP use IP as source IP address
+tcp send query via TCP
+ignore ignore truncation (don't retry with TCP)
+aaonly set authoritative answer bit
+adflag set authenticated data bit
+cdflag set checking disabled bit
+norecurse set rd bit to 0 (recursion not desired)
+edns[=N] use EDNS with specified version (default 0)
+ednsflags=N set EDNS flags field to N
+ednsopt=###[:value] set generic EDNS option
+bufsize=NN use EDNS with specified UDP payload size
+dnssec request DNSSEC RRs in response
+hex print hexdump of rdata field
+nsid send NSID (Name Server ID) option
+expire send an EDNS Expire option
+cookie[=xxx] send EDNS cookie option
+subnet=addr send EDNS client subnet option
+chainquery[=name] send EDNS chain query option
+padding[=N] send EDNS padding option (defblocksize 128)
+walk walk (enumerate) a DNSSEC secured zone
+0x20 randomize case of query name (bit 0x20 hack)
+emptyquestion send an empty question section
+generic use RFC3597 generic type/class/rdata format
-4 perform queries using IPv4
-6 perform queries using IPv6
-x reverse lookup of IPv4/v6 address in qname
-d request additional debugging output
-k/path/to/keyfile use TSIG key in specified file
-iNNN use specified message id
-y<alg>:<name>:<key> use specified TSIG alg, name, key
+tls=auth|noauth use TLS with|without authentication
+tls_port=N use N as the TLS port (default is 853)
+tls_fallback Fallback from TLS to TCP on TLS failure
+tls_hostname=name Check hostname in TLS server certificate
+https[=url] use HTTPS transport with optional URL
``
IXFR (Incremental Zone Transfer) queries are supported with the syntax
of "IXFR=NNNN" for the <qtype>, where NNNN is the zone serial number.
Example usage:
pydig www.example.com
pydig www.example.com A
pydig www.example.com A IN
pydig @10.0.1.2 example.com MX
pydig @dns1.example.com _blah._tcp.foo.example.com SRV
pydig @192.168.42.6 +dnssec +norecurse blah.example.com NAPTR
pydig @dns2.example.com -6 +hex www.example.com
pydig @192.168.72.3 +walk secure.example.com
pydig @192.168.14.7 -yhmac-md5:my.secret.key.:YWxidXMgZHVtYmxlZG9yZSByaWNoYXJkIGRhd2tpbnM= example.com axfr
pydig @192.168.14.7 -yhmac-sha256:my.secret.key.:NBGFWFr+rR/uu14B94Ab1+u81M2DTqB65gOv16nG8Xw= example.com axfr
pydig @185.49.141.38 +tls=auth +tls_hostname=getdnsapi.net www.ietf.org AAAA
pydig +padding=256 blah.example.com AAAA
pydig +https www.ietf.org A
# Additional Notes
For TSIG (Transaction Signature) signed messages, the program supports
HMAC-MD5/SHA1/SHA256/SHA384/SHA256. It doesn't yet support GSS-TSIG.
It decodes but does not yet verify signatures in DNSSEC secured data.
It does not perform iterative resolution (eg. dig's +trace).
Specific features of TLS depend on the version of Python in use. TLS server
certificate verification and hostname verification require quite recent
versions of Python.
For +https, if no URL is specified, then by default Cloudflare's DNS over
HTTPS server is queried (https://cloudflare-dns.com/dns-query).
# Pre-requisites:
* Python 3
* "requests" module
# Installation:
1. pip3 install requests (if necessary)
2. python3 setup.py install
# License
Shumon Huque
E-mail: shuque -at- gmail.com
Web: https://www.huque.com/
Copyright (c) 2006 - 2017, Shumon Huque.
All rights reserved. This program is free software; you can redistribute
it and/or modify it under the same terms of the GNU General Public License.