Instructor: Network mapping.
So in the last lecture when we talked about footprinting,
I had mentioned that we can use tools like Zenmap
or Nmap to map out our network.
So what does that really look like?
Well, when we talk about network mapping
we're going to use different tools that are
going to do this during active reconnaissance.
And what they're going to do is figure out
what the network looks like, based on using things like
ICMP echoes, ping packets, and other things like that.
It'll do this by looking at the time to live responses.
It'll do this by using traceroute information.
And also other responses from the network devices.
Weather they error out or give a response,
that tells us a little bit about these networks too.
And again, like I said, Zenmap and Nmap
are two of the most useful tools for this.
Zenmap is a graphical version of Nmap
and uses Nmap as its scanning engine.
Nmap is by far the most popular
network scanning program in the world.
So, when you run your scan, what do the results look like?
Well, here's an example.
Right here you'll see this came from Zenmap.
And this is a network map that you can see
that has been created automatically by the tool.
I did a full network scan of the network,
and the local host, which in my case was 10.3.0.5,
you can see that dash line to the green dot,
was my kali linux machine.
And I locally scanned all three subnets,
which in my case was 10.3.0.0,
10.3.1.0, and 10.3.2.0.
And you can see how these networks all map
to each other, based on this diagram.
So from my machine, I'm able to reach all of those
and I can see which networks they're in
and what this network looks like.
So you can see that 10.3.0.1 for instance, is a router,
and from there it can reach these other things, right?
And you can see that graphically in this depiction,
in this little fish eye.
Now this isn't the most helpful network map,
doesn't have a lot of the details that I would like,
but you can see how the green ones, and the yellow ones,
and the red ones are based on the time to live
and how long it took to get there.
Now, there's other more intensive tools
that we'll use later, but this is just to give you an idea
of one tool you can use to create a network map.
So, when we talk about some challenges to network mapping,
there's a lot of different challenges.
The first one is firewalls.
Firewalls and layer three switches
have access control lists, and those access control lists
can actually prevent things from being mapped fully
by blocking certain types of packets and responses.
So, for instance at my network,
we don't respond to ping requests.
So if you send out an echo reply using ICMP,
you're not going to get a reply back, right?
But that tells you something.
And if you do a trace route it will tell you
that there's a firewall there, right?
That's what you're going to be able to figure out.
Wireless networks are also a big challenge
because they can be on and off the network very quickly
and they're DHDP scopes tend to be a little bit different,
and their ranges tend to be different.
So that can be a challenge for your network map.
Being able to determine what's wired
versus what's wireless is also a challenge there.
Virtualized networks and infrastructure
are a huge challenge, because if you're
on the actual network itself, like on the management land,
you may see the virtual machine server,
which has its own IP, but you won't see all of the things
that are natted into it that might have
five, six, seven, or eight servers inside that one box.
So that can be an issue, and virtualized infrastructure,
virtual routers and switches can also become a problem.
And if your organization uses cloud services,
that's another challenge for network mapping,
because you may not even have access
to all of that infrastructure to be able to fully scan it,
because it may be something that's more like
a platform as a service, software as a service,
network as a service, something of that nature,
that is kind of hands-off and you just get
the actual platform from it, you don't get to access
to the physical devices at the lower levels.
So these are some of the challenges you have to keep in mind
when you do networking and when you start doing
network mapping in the future.
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