Ubuntu Manpage: firewalk - Active Reconnaissance Network Security Tool with Extreme Prejudice

NAME

       firewalk - Active Reconnaissance Network Security Tool with Extreme Prejudice

SYNOPSIS

       firewalk [-dhinprSsTtvx] target_gateway metric

DESCRIPTION

       Firewalk is an active reconnaissance network security tool that attempts to determine what
       layer 4 protocols a  given IP forwarding device will pass.  Firewalk   works   by  sending
       out  TCP  or UDP packets with a TTL one greater than the targeted gateway.  If the gateway
       allows the traffic, it will forward the packets to the next hop where they will expire and
       elicit  an ICMP_TIME_EXCEEDED  message.  If the gateway hostdoes not allow the traffic, it
       will likely drop the packets on  the floor and we will see no response.

       To get  the  correct  IP  TTL that will result in expired packets one beyond  the  gateway
       we  need   to   ramp   up   hop-counts.   We  do  this  in the same manner that traceroute
       works.  Once we have the gateway hopcount (at  that point the scan is said to be  `bound`)
       we can begin our scan.

       It  is significant to note the fact that the ultimate destination host does not have to be
       reached.  It just  needs to be somewhere downstream, on the other  side  of  the  gateway,
       from the scanning host.  Please see http://www.wiley.com/cda/product/0,,0471205443,00.html
       for more information on Firewalking and networking security tools in general.

COMMAND-LINE OPTIONS

If an option takes an argument, it proceedes the option letter, with the default in
parenthesis.

-d 1-65535 (34434)
Specify the initial destination port to use during the network discovery
(aka TTL ramping) phase.

-h Program help.

-i interface_name
Specify interface to use. Only necessary on multi-homed machines.

-n Do not resolve IP addresses into hostnames. This saves a DNS lookup and
speeds the scans (mainly during network discovery).

-P 1-2000 (0) Set a network writing pause which may be necessary to keep the program from
flooding the network.

-p TCP, UDP (UDP)
Type of scan to perform.

-r Strict RFC 793 compliance. This only comes into play when doing a TCP scan
when your packets have an expire vector of one and your metric host is one
hop from your gateway. Since the packets will reach their destination,
they will not expire, so we look for terminal responses. For a TCP port in
the listen state, we will get back a SYN|ACK with the ACK as our SEQ + 1.
However, for a closed port, the response is stack dependent. If the host
is RFC compliant we will receive an RST|ACK with the ACK as our SEQ + 1.
However, if the host is not compliant (ie: microsoft) then the best we can
do is inverse tuple matching (which is the default).

-S 1-65535,... (1-130,139,1025)
Specify the ports for the scan. Ports may be specified in ranges,
delimited by dashes, and multiple ranges may be specified, delimited by
commas. Omitting the terminating port number is shorthand for 65535.

-s 1-65535 (53)
Specify the source port for the scan (both phases).

-T 1-2000 (2) Network packet reading timeout. This is the time firewalk will spend
waiting for a response before timing out.

-t 1-25 (1) Set the initial IP time to live (TTL) value. If a target gateway is known
to be (at least) n hops from the source host, the TTL can be preloaded to
facilitate a faster scan.

-v Dump program version and exit.

-x expire vector (1)
The expire vector is the number of hops that the scanning probes will
expire, past the gateway host. The binding hopcount is the hopcount of the
gateway + the expire vector.

COMMAND-LINE EXAMPLES

CAVEATS

AUTHOR

       Mike D. Schiffman <mike@infonexus.com>

BUGS

       Please send bug reports to mike@infonexus.com