Hello everyone. So in this video we
are going to see the fin type of scan.
The syntax of doing this scan is nmap hyphen
S capital F the target IP
address and the port number.
This is another very stealthy scan that sets
all the TCP header Flags to fin.
Ally sneaks through State Electric firewalls and
packet filters by turning on different TCP Flags
like fin.
However for non-window servers protected by a
firewall this can be a way to get
through.
Remember in fins. Can the fin
flag is been set successfully note.
The port is closed. It replies with reset act and
if it is open it replies with fin.
So what actually happens in fin type of scan?
As you can see on the left hand side is the end map
machine through which we are going to perform the scan.
On the right hand side is the server which we are going
to scan.
So the nmap sense are request, which is fin type.
and if it receives a reset tag
Which means the port is closed.
So, let's see what kind of responses can we
receive and based on that?
What is the state of the sports?
So if we receive no response, even
after Transmissions, then the state is assigned
as open or filtered.
If you receive TCP reset packet, then the
port is closed.
If we receive icmp and reachable, then the port is
assigned the status of filtered.
Let's see the Wireshark packet breakdown quickly and understand
what actually happens in the background.
So as you can see a fin type of request is sent for
the port 22 as well as Port 23.
On Port 23 a reset Act is received which means
this port is closed.
So what are the advantages and disadvantages of this
can?
As you can see the desert Advantage is it
is unreliable and the advantage is it is
still the and it can bypass some firewalls
and packet filters.
So it is the Practical time and let's see fin scan
in action.
As you can see onto the screen. I'm going
to type the command into my terminal that is
nmap.
Hyphen, SF. Let's start
for fin scan the target IP address.
And hyphen V to see the output in verbose mode
as you can see over here.
It has initiated a fin scan.
Now we have got the output as we
can see our all the three ports are marked as
open and filtered.
And the host is up. This is because nmap is
not able to identify the correct Port status
as it has received reset act
for all the three ports.
As you can see into the Wireshark packets,
if you look closely for all the packets
a fin was sent and reset Act is
received.