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Difference between revisions of "DNS"

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There are many useful free DNS utilities on the internet. One that in particular is endorsed by us is [[YouGetSignal http://www.yougetsignal.com/tools/web-sites-on-web-server/]], that tool specifically. Essentially, you enter a domain or an IP and it will return a list of domain names that point to the ip.
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There are many useful free DNS utilities on the internet. One that in particular is endorsed by us is [YouGetSignal http://www.yougetsignal.com/tools/web-sites-on-web-server/], that tool specifically. Essentially, you enter a domain or an IP and it will return a list of domain names that point to the ip.
  
 
See [[protocols]] for more information.
 
See [[protocols]] for more information.

Revision as of 17:07, 4 January 2012

Dymic Name System or Domain Name System

DNS resolves hostnames to IP addresses and vice versa. DNS records also control the appointment of servers to control e-mail.

DNS Basics

The DNS system is used to resolve domain names (such as www.blackhatacademy.org) into 4-byte addresses (such as 173.245.60.117) known as IP addresses or (more rarely) DNS addresses. It can be used to obtain a wealth of information concerning a website, all of which can be useful for troubleshooting, penetration testing and recon.

DNS Recon

In this example, random.com is given as a site that the hacker wishes to learn more about. The first step in a hacker's DNS recon might be to type:

host random.com

That will return basic information on the site, ip addresses (a records, aaaa for v6) and mail servers (mx records). For a little bit more information, use the -a flag, it will return everything from txt records to dnssec records.

Taking it a bit further, you can really start to pull a lot of information from DNS given the right circumstances. For example, if a domain name server has axfr's (zone transfers) enabled for everyone, you can get a list of subdomains for any domain name on that server. The easiest way to do this would be something like this:

host -tns random.com

This would give return the dns servers for random.com, allowing you to do something like:

host -l random.com. ns75.worldnic.com

In order to perform a successful zone transfer, you usually want to directly specify the name server. Here is an example of a successful zone transfer:

outlookccc.wideopenwest.com has address 64.233.207.77 mail.outlookccc.wideopenwest.com has address 12.152.37.50 pop-13.wideopenwest.com has address 64.233.207.59 pop-14.wideopenwest.com has address 64.233.207.60 portal.wideopenwest.com has address 64.233.207.39

There are many useful free DNS utilities on the internet. One that in particular is endorsed by us is [YouGetSignal http://www.yougetsignal.com/tools/web-sites-on-web-server/], that tool specifically. Essentially, you enter a domain or an IP and it will return a list of domain names that point to the ip.

See protocols for more information.

DNS Server Software