Lesson 71 : IMPC redirection Process and Functions Video Lecture | Ethical Hacking using Kali Linux (in English) - Software Development

hey guys into the next tutorial of
ethical hacking and pen testing with our
own operating system Kali Linux so in
the previous tutorial I taught you about
the ICMP - direction and just before I
proceed a lot to give you a short I will
go through a short discussion of my
previous okay so over here it would
appear as if the ping program does not
revile you ate the routing table during
runtime the reason for this is explained
quite elegantly by Richard Stevens as I
told you previously that this function
only works for raw IP protocol that is
UDP and TCP this time our packets have
taken the expected path and immediately
through RC rather than first traversing
the default gateway are one for every
destination that hosts a receives a
redirect it will install a redirect host
based route in its routing table in this
small example it would potentially say
install up or set up up to 255 routes
and 32-bit masts just consider how many
potential host based routes this could
generate for networks with more
inclusive prefixes for example a single
route with Class B masts potentially add
up to 65535 redirects certainly it would
be a better for host a to be fitted with
some better method of discovering what
traffic to send through r2 instead of
relying on ICMP redirect because
actually going ahead and redirecting
65535 stating that it will just be in a
loop and you waiting like forever to go
ahead and get the redirect thus
depending upon the OS implementation
these host-based routes can have the
characteristic of being short-lived
solaris implements aggressive aging
which where slowest operating system it
implements aggressive aging where who
directs will only last for a specified
amount of time so let's say for example
if I have reiterated something to a and
it does not respond for let's say around
10 seconds 20 or 30 whatever the time
may be then the timer will expire and it
will not be able to go ahead and send
anything back each redirect is given a
short lifetime value and will be autumn
removed from the routing table when the
timer expires this is to ensure that
redirects do not remain in the routing
table indefinitely at the risk of
further going hurt and freezing other
data as well so in BSE networking code
redirects will be removed if they are
being used by TCP and only after the
fourth consecutive retransmission
attempt they will be removed router and
gated perform similar forms of redirect
expiration since I simple directs our
dynamic and may not reflect the most
current apology it is nice to have an
automated method of redirect expiration
note that ICMP redirects can also cause
problems in firewall environments flow
traffic patterns or non-deterministic
this consider this following example
because it looks like okay just let me
check so over here if this figure looks
quite similar to the previous diagrams
but suppose that host is default gateway
is not a firewall that is it is it is
now a firewall and stuff router
hijos to a were to receive an ICMP
redirect from its default gateway
probably only part of the traffic flow
from host bid to host the host eight
hose we would be seen by the firewall as
synchronous flows pose
particular problems for stateful
firewalls because they need to see the
entire flow cycle this is especially the
case for TCP traffic when individual
packets can point to straight
transmissions such as a beginning such
as sin or sin wa - AC came or at the
middle such as the ack psh all the ends
just filmed fin ACK rst if the firewall
were only to see the beginning of the
flow or part of it it may take an extra
long time to timeout entries from the
session table because it was not able to
see the middle and the end of each flow
and again it may again go over and get
disconnected so the problem is
accelerated if an XC ICMP literate only
gets acknowledged by a host after the
initial TCP handshake has completed
firewalls rely on timeouts to age-old to
edge out all entries in cases where TCP
control traffic it's not available
although embryonic TCP connection
timeouts are generally an order of
magnitude smaller than
mods for establish TCP connections they
can still lead to firewall session entry
table getting in converting into
exhaustion so a common design flaw is
that a firewall security in this
topology could be bypassed altogether
if host with a were to simply create a
static route to host B instead of using
its default gateway this is probably not
what the network architect intended when
placing a firewall info in front of the
host a if she or he was talking to
filter traffic properly from host it was
V so in John what I am trying to say is
that whenever some data has been sent
out in the host I should know whether it
should use the default gateway through a
firewall or a block router or it should
know that the it should go through the
board - that is router - through it it
should be able to connect to B so the
person needs to know where the data it's
know where it is actually going through
finally redirects could be used by an
attacker that has some knowledge of the
Raider topology to inject malicious
routes into the hosts routing table let
cool this code case a denial of service
against the host or specific destination
it is trying to reach one example of
such a program would be I see Jen I'll
go ahead and talk about that at the
later part of this tutorial
it is a utility divided by an author
simply for research that is capable of
sending any type of ICMP unreachable
message holder Microsoft where ions are
much more susceptible to this form of
attack since let's security precautions
are out in place and new opening system
make more make this more difficult to
spoof but not altogether impossible
though but there is still a good news
fortunately there are effective tactics
when dealing with networks that wish to
send ICMP redirect aside from disabling
them all together because disabling them
will not just go down helpers right
that's why so generally these types of
network can be reaaargh attacted so one
of the following means a changing tenet
of a configuration to remove the
possibility of multiple non redundant
gateways for a host be changing the
network configuration to make that
gateways redundant see adding optimum
static routes to the host for the
networks in question and the last and
the four most important adding the
capability for learning dynamic routes
to a host so and the last and the
foremost part would be
not deform was the ultimate thing that
you would like to do in a in your
environment would be to go ahead and
make the host intelligent enough to
understand whether it should go ahead
and pass through a firewall or should go
through any other gateway through which
it could go in and access get access or
give access to host B and the firewall
should be good enough to understand
whether it should go ahead and force
feed the data to good and cancer itself
if it is going to go through another
gateway all it should code and allow it
quickly this by going and scanning it
from the start to middle as well as the
end and knowing how to go ahead and
redirect that so though ICMP redirect
serve to point out issues with sub
optimal routing network lis architecture
ensured be favored over there use
well-designed networks should never lend
themselves to the lands on or desire for
I simply redirects for reasons of
performance consistency reliability and
security I simple rates are bad that's
why so in in short that you should make
your network so good that you should be
able to know whether it should be able
to or in fact you should never be able
to you should not go ahead and disable
ICMP direction I am saying but what I am
trying to convey is that you should be
able to know whether your you should be
able to go ahead and our transfer data
through different routes and to
different gateways and even if one even
let's say for example if data if the
whole state transfers some packets to
let's say let's assume that this
firewall is a router that's good and go
back to my previous one so let's say for
example if the host a tries to send
something to host through the router a
and as soon as it gets a redirect it
should go ahead and quickly pass it
through router better than going on and
searching default gateways so there
should be specific gateways set up
already before anything goes further on
so that you know exactly what is
happening and it should know exactly
from where which is going and the final
thing that I'd like to convey to you
would be avoid traffic jams
try quantum tunneling it is the most
famous quote of all time I don't know
who said it exactly but this is very
famous so quantum tunneling
to be in technical terms I can say as
using SSH secure layer it is going out
and using a most famous application
which is used that is called as putty
beauty TV and you can go ahead and
download it from over here let me just
show it out to you so you can see this
is a free SH and telnet client for
Windows and you Ubuntu calenus they have
all inbuilt ssh clients so you don't
need to worry about that per Windows you
can go and use this and this is a very
or I can say extremely secure telnet
line used by most of the people out
there you can go to connect to any
Windows you want through the SSH tunnel
and you won't even face any kind of
traffic jams because it's quite or
extremely fast and you can run multiple
computers various using graphic user
interface can go ahead and run only one
computer yes so that is it for this
tutorial guys in the next tutorial I
will actually be going ahead and showing
you some actual examples are going out
and killing your network or using some
tactics to go ahead and defend you own
network as far as using your exploits
and injecting them into softwares and at
that point of time we will be using it
recap which is again used for
man-in-the-middle attacks