dnshjmon

dnshjmon is a free tool to monitor public DNS records and report hijacks

Syntax

python dnshjmon.py [arguments]

Valid arguments:

 -h                   : show help

 -d <dns configfile>  : full path to dns config file.
                        Defaults to dnshjmon_dns.conf in current folder

 -s <smtp configfile  : full path to smtp config file.
                        Defaults to dnshjmon_smtp.conf in current folder

 -n <dns server file> : full path to file that contains
                        DNS server IP addresses
                        Use this setting to overrule the default behaviour
                        of using the OS DNS server configuration
 ** Note: option -n requires the python-dnspython library **
          (http://www.dnspython.org/)

 -mail                : Test e-mail configuration

DNS Config file

This is a flat ascii file (dnshjmon_dns.conf) that contains the list with hostnames that need to be checked and the list with valid IPs for that hostname.

hostname=ip

You can specify multiple IP addresses and/or even use CIDR notation. Simply separate entries with a comma:

hostname=127.0.0.1,192.168.0.1/25

If you want to exclude a certain IP, prefix it with a dash

hostname=127.0.0.1,192.168.0.1/25,-192.168.0.5

SMTP Config file

This file (dnshjmon_smtp.conf) will be created the first time you run dnshjmon.py, using an interactive wizard. If you want to add additional mailserver configurations or change the existing one, simply edit the conf file. You can test if the mail configuration works correctly by using the -mail argument. By default, emails will be sent with high-priority and requesting a return-receipt.

Custom nameservers

By default, dnshjmon will use the OS DNS configuration. If you want to use specific nameservers, you'll need to install the python-dnspython library. dnshjmon will automatically detect if the library is present and allow you to use the -n option. Using -n, you can specify the location of a flat ascii file that contains the IP addresses of the nameservers to use.

Usage

Simply schedule the script as a Cron job or Scheduled Task. Please note that the script was written and tested against python 2.7. More info: https://www.corelan.be/index.php/2013/12/29/a-chain-is-only-as-strong-as-its-weakest-link-dns-hijack-monitoring/

Disclaimer

Use at your own risk.