Fierce is a semi-lightweight scanner that helps locate non-contiguous IP space and hostnames against specified domains. It’s really meant as a pre-cursor to nmap, unicornscan, nessus, nikto, etc, since all of those require that you already know what IP space you are looking for. This does not perform exploitation and does not scan the whole internet indiscriminately. It is meant specifically to locate likely targets both inside and outside a corporate network. Because it uses DNS primarily you will often find mis-configured networks that leak internal address space. That’s especially useful in targeted malware.



fierce [-dns] [OPTIONS]


       -connect	        Attempt to make http connections to any non RFC1918
		       (public) addresses.  This will output the return headers but
		        be warned, this could take a long time against a company with
	                many targets, depending on network/machine lag.  I wouldn't
		        recommend doing this unless it's a small company or you have a
		        lot of free time on your hands (could take hours-days).  
		        Inside the file specified the text "Host:\n" will be replaced
		        by the host specified. Usage:

	        perl -dns -connect headers.txt

	-delay		The number of seconds to wait between lookups.
	-dns		The domain you would like scanned.
	-dnsfile  	Use DNS servers provided by a file (one per line) for
                reverse lookups (brute force).
	-dnsserver	Use a particular DNS server for reverse lookups 
		(probably should be the DNS server of the target).  Fierce
		uses your DNS server for the initial SOA query and then uses
		the target's DNS server for all additional queries by default.
	-file		A file you would like to output to be logged to.
	-fulloutput	When combined with -connect this will output everything
		the webserver sends back, not just the HTTP headers.
	-help		This screen.
	-nopattern	Don't use a search pattern when looking for nearby
		hosts.  Instead dump everything.  This is really noisy but
		is useful for finding other domains that spammers might be
		using.  It will also give you lots of false positives, 
		especially on large domains.
	-range		Scan an internal IP range (must be combined with 
		-dnsserver).  Note, that this does not support a pattern
		and will simply output anything it finds.  Usage:

	perl -range 111.222.333.0-255 -dnsserver

	-search		Search list.  When fierce attempts to traverse up and
		down ipspace it may encounter other servers within other
		domains that may belong to the same company.  If you supply a 
		comma delimited list to fierce it will report anything found.
		This is especially useful if the corporate servers are named
		different from the public facing website.  Usage:

	perl -dns -search corpcompany,blahcompany 

		Note that using search could also greatly expand the number of
		hosts found, as it will continue to traverse once it locates
		servers that you specified in your search list.  The more the
	-suppress	Suppress all TTY output (when combined with -file).
	-tcptimeout	Specify a different timeout (default 10 seconds).  You
		may want to increase this if the DNS server you are querying
		is slow or has a lot of network lag.
	-threads  Specify how many threads to use while scanning (default
	  is single threaded).
	-traverse	Specify a number of IPs above and below whatever IP you
		have found to look for nearby IPs.  Default is 5 above and 
		below.  Traverse will not move into other C blocks.
	-version	Output the version number.
	-wide		Scan the entire class C after finding any matching
		hostnames in that class C.  This generates a lot more traffic
		but can uncover a lot more information.
	-wordlist	Use a seperate wordlist (one word per line).  Usage:


cyborg@cyborg:~$ fierce -dns -threads 5 
DNS Servers for

Trying zone transfer first...
		Request timed out or transfer not allowed.
		Request timed out or transfer not allowed.

Unsuccessful in zone transfer (it was worth a shot)
Okay, trying the good old fashioned way... brute force

Checking for wildcard DNS...
Nope. Good.
Now performing 1895 test(s)...

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