Time
10 hours 41 minutes
Difficulty
Beginner
CEU/CPE
12

Video Transcription

00:05
this module we're gonna talk about I p addresses ports and protocols.
00:09
So an I p address
00:13
lives at the later three. It's after we've already translated the Mac address
00:19
into these and that, and we moved to Layer three, and now we have
00:23
T's P i p coming in. And so T's Pipi uses eyepiece. Or, uh,
00:29
you're not protocol Joses
00:32
to identify machines or devices on the network
00:36
I P address, at least with I p before is 32 bits and links, which is divided into four AQ debts.
00:44
The Oct It's air separated by dots.
00:47
This example. Everything translates the binary and computers that would be the buying a representation of
00:52
192.1 68. That one. That one.
00:57
The I P address reflects both the network that the host is on in the host itself. What does that mean? So that means the 1st 3 octopus usually defined the network that belongs to,
01:10
and the last octet would define the actual host, which would be unique to that network
01:15
in a diagram example.
01:18
So if we have an I P address
01:23
tend er
01:26
10 10
01:29
55
01:32
that would commonly refer to an entire network that is known behind a common router
01:38
or switch as
01:42
S. O. C.
01:46
Yeah.
01:56
So say this switch is everything Behind the switch is the network 10 dup
02:00
10.
02:04
So each I pee behind here
02:07
would be identified with a different forthe octet, which would identify it individually as a host. So in this case, we could say
02:15
this one was 10.10
02:17
10 duh.
02:21
Uh, five
02:23
this one viki 10.6
02:24
0.7 They would all have the same network.
02:34
That's how they all know which network to be long to is by the 1st 3 AQ tents there. So those 1st 3 numbers can change if they're on different network, so we could have another switch over here with a different network
02:47
will be tender.
02:49
Tenn 0.9
02:52
zero indicates the entire network
02:54
and each of those and then each of the boxes under here would have the same three numbers.
03:04
Five.
03:08
They could only have values between one and 2 54
03:14
So anywhere, the doctor it's cannot be valued
03:17
between that's over 2 54
03:21
They cannot be 00 identifies the network that the coast belongs to.
03:31
Now we do have what's called private I p addresses.
03:35
They're defined for internal use.
03:38
So these reserved and these air not row doble on the Internet. So with I pee before we have a limit number of Internet
03:46
addresses available, and as more people get on the Internet, those addresses are being used up.
03:52
So to avoid depletion, if you do not have to have a device that directly sits on the Internet,
03:57
you can use one of these private I P addresses.
04:00
And
04:02
it saves Internet eyepiece. But also, if for some reason, your packets from your computer if they have with the P addresses trying it on the Internet,
04:11
any Internet router would drop them because they're non row double on the Internet.
04:15
So you see, the common ones you see are like 10. Like I was using it. My example. So I say $10.0.0 because I can use
04:21
any value in the 2nd 3rd octet from 1 to 2 55
04:26
so I could have a network that's
04:28
Tenn 0.1 dot one duck
04:30
13 to 55 I could just keep building it up. So that's that's a huge network
04:36
and the other one you commonly see, especially on home right home routers and home devices, is the 1 92.1 68
04:49
But the goal here is to fold is one that we don't waste private eye Pete. We don't waste public I p addresses, and I pee before so most corporation will have their own internal I p scheme
05:00
with not rideable Internet addresses and then just own a few external facing
05:05
our Internet facing I. P V four addresses.
05:12
Come on.
05:13
So I have to be six. It's the next version of the Internet protocol. So far, we've been talking in terms of
05:18
version four.
05:23
Ivy. Six came around, mainly because we're running out of I P four addresses
05:29
as significantly work as significant. More capacity could use 128 bits for the addresses instead of 32
05:38
It also has a smaller head, so it has less overhead.
05:42
Adoption has been
05:45
so so there's federal mandates for when
05:47
government agencies need to adopt it. But a lot of people
05:50
I have not.
05:53
The main reason Fried, 56 was really just because we're running out of I P addresses
05:59
that your address
06:00
and I V six you can see is a lot different because it's
06:04
using four hex digits instead of our typical
06:09
10 base
06:10
that we see the night before.
06:13
This is typical in to be separated by Coghlan's instead of dots
06:19
in the equivalent private I'd pee Space
06:24
is
06:25
is this I p address an I P V six format, which would be the equivalent of a
06:29
I
06:30
10 or 1 72 or 192 based network.
06:35
There's other comparison, so you could see the 32 bit address
06:39
of Top private before decimal format,
06:44
which gives us
06:47
4.3 times 10 to the ninth addresses. But
06:51
with the new I P scheme with 100 20
06:55
i p v six address,
06:58
it's insane. I don't even know where we'd start with saying that number. Besides using
07:04
3.4 times 10 to the 38
07:08
we're the biggest challenges like V six is. It uses Hexi decimal, which most of us which a lot of people aren't familiar with compared to regular decimal.
07:20
So T's V. I P
07:23
uses two types of protocol
07:26
commonly called TCP transport Control Protocol and UDP User data Graham Protocol.
07:32
The key difference between the two is you want to use. TCP is used when you want to make sure the connection
07:40
is, uh has to be defendable has to be dependable. Guaranteed delivery. What UDP is connection list so it's not guaranteed. That's gonna make it either. End
07:55
so T Examples of TCP would be file transfers, email, Web page, Web page requests
08:01
We need a file transfer go through guaranteed because if it doesn't go through right to follow, be corrupted.
08:09
UDP is more likely to be used for such things. It's streaming
08:13
of audio and video,
08:16
I said. No guarantee of delivery.
08:18
It's best effort.
08:28
So we'll go over some of the examples of ports and protocols that used TCP and UDP and talk about why they use
08:33
one or the other.
08:37
So port so talking about P addresses, the next step is port supports are usually are always associate with an I P address,
08:43
and the port is used to a uniquely identify application of processes.
08:48
They're running on that
08:50
poster device
08:52
so we may have multiple network type service is being offered on the host before we have the eyepiece address. How do we access that specific service running on the host.
09:01
So the poor is kind of like which mailbox to go to on that machine.
09:05
Which door do we open in the house to get to where we want
09:09
And the ports always be TCP or UDP.
09:13
Remember, TCP is guaranteed delivery. UDP is best effort.
09:20
So we go over some of the common default ports they would see on most
09:24
networks not know surely on your host. But your host would use these. Your computer would use these ports to communicate with other servers.
09:35
So we're gonna go through each of the East. I'm not gonna read them all by themselves.
09:41
So first is FTP and T F T P
09:45
FTP stands for file transfer protocol goes over port 21 for control and 20 for the actual data. So if you're opening, if you're having FTP go through your firewall, gonna make sure you have both
09:56
20 and 21 TCP ports open.
10:00
Now we're using TCP because we're transferring files and want to guarantee that they're gonna be delivered. It's a state full. It's a guaranteed session because you're gonna log in.
10:07
The biggest problem with so file transfer protocol has been around for a while. Very common way to host files. It's basically you connect with FTP client, which could be gooey or could be at the command line. You log in with user name and password, and then you can download files.
10:22
So FTP was around way before the Web. It was a common way to transfer files over the network.
10:28
The biggest problem FTP now is that it's
10:33
very insecure because nothing is encrypted, not even the user name and password.
10:37
So when you got a law again, it's the user name and password or transferred over the clear.
10:43
You know, security wasn't the main goal when they developed FTP when computers were first coming out. Uh, the Internet wasn't around. It wasn't
10:52
being used as widely as it is now, so they weren't thinking security in these old protocols.
10:58
It's best to avoid FTP unless absolutely necessary
11:01
in today's environment, since it is so easily detected
11:09
and so, especially if, like a lot of people do they use the same password for everything. So if they get the password from your FTP account, there's a good chance they have the password from something else.
11:18
The most time you would have a client, you'd access an FTP server that think of it as an early way of doing file share.
11:26
T f T P is called Trivial File Transfer Protocol.
11:30
It's a simpler version of FTP and runs on you Deport 69
11:35
Very simple Autistic. Um, upload a file. Er, get a file
11:39
today. T T f T P is mainly used for
11:43
booting computers over the network.
11:46
So when you boot a computer from land will go look for a key FTP server. Or you could specify a T FTP server. Basically download a small filed I'll tell it. Okay, go look here to boot. And here's the rest of the instructions to follow through
12:05
and says T f T P is only those required whose name log in no way does very small files and typically used just abou a computer. That's why it's over UDP
12:16
It's not interactive session like you would with a teepee.
12:20
So with the insecurities FTP and,
12:24
uh, telling that which will talk about also in a second
12:28
there's s s h, so shh replace Telnet.
12:31
Telling a is a program that allows you to remotely access
12:35
computers, mainly UNIX machines and switches and routers from the command line using plain text.
12:43
It's only for doing like commanding control. It wasn't for downloading uploading files of more just the typing commands. It wasn't completely in the clear.
12:54
So now we have a CH,
12:56
which is a secure replacement for talent and also security placement for FTP
13:01
operates in Port 22
13:05
but does more than just operate as a security placement for telling. An FTP can also use it to do what's called tunneling, where you can send other traffic such as Web and email.
13:13
That's what basically does is you log in with user name and password to another machine running Sshh, as we were in the estate server,
13:24
encrypt using and password and that encrypts the rest of your session.
13:28
All the data going back and forth is in the is encrypted or report 22
13:37
and that's called a tunnel. So now you have this created. You can use it to pass other types of information,
13:43
such as your Web browsing activity or connect to other ports. And it'll be encrypted through that initial logging that you already did,
13:50
almost like a VPN,
13:52
just not as user friendly
13:54
but probably more powerful.
14:03
So secure. FTP is the file transfer port portion of estates
14:07
still using Port 22 because
14:11
we're using the same username, password, same
14:15
same technology.
14:16
But we can use this to also transfer files much like we did with FTP.
14:20
But again, your your name and your password is encrypted,
14:26
and so are the file transfers.
14:35
So
14:37
tell that, like I mentioned a few minutes ago, I should have had this to slides earlier.
14:41
Port 23
14:43
TCP. This a very plain text
14:46
log in, usually to a router switch. It's not gooey,
14:50
no graphical interface.
14:54
This was the only way to communicate with early Lennox UNIX machines
14:58
before the days of Windows,
15:03
but it's still available on older switches and routers.
15:07
That's the way you can remote access them to change configurations.
15:11
A lot of the newest switches and routers
15:13
now support Sshh so you don't have to use tone. It's so tell that should only be used in case of extreme case, uh, extreme emergencies, where there's no other option to access the machine
15:26
melon consider still turned off, telling that only access to that machine physically, if that's all that's available
15:35
at some TV. Simple male transfer protocol operates important 25 TCP
15:41
This support We're used to send mail
15:43
from client to servers and between servers.
15:46
So when you connect to a mail server or you're eating your outlook earlier or whatever your E mail plane is, it goes to send mail. It's gonna contact the mail server over Port 25.
16:00
So to kind of put it back in perspective, bit blowing it out again. If I have one server that's running, Web
16:07
and email,
16:08
how do I know the port tells me which which programmed to go to, Because if I just go to the I P address, I don't How am I gonna know if I'm accessing the Web server or from access in the mail server or I'm going to S H The poor is what directs us to
16:25
toe which program we're gonna use on the server.
16:29
SMTP has no authentication by default.
16:33
Before, we had what we called open relays where we didn't have any kind of authentication or any kind of I p control so anyone could send mail from anyone else's mail server
16:41
that's called being an open relay, and it caused a lot of the early spam on the Internet.
16:47
You don't see that very often. A lot of eye of peace. Internet service providers actually block port 25 so you can't run your own open relay or your own mail server.
17:00
Most SMTP servers now support some kind of authentication.
17:04
And so I mean, support encryption
17:08
pop. Very popular. One port 110 TCP Um, I kind of noticed. I say popular, but I guess now, with Web mail, you don't see Pop and I map as much
17:19
because they want to access their page of the Web mail. But using some kind of email client to access your
17:25
your Web your your email from another server, you're likely using either popper. I map port runs over Wound zero
17:33
basically goes and clears the mail server using your username password and download your mail messages for you to your local client.
17:45
I'm map. Run the import. 1443 Internet Message Access protocol.
17:51
Instead of downloading the messages and taking him off the server pop, think of as a retrieval.
17:56
I'm map allowed you to keep it on the server and made and sink it between the server and your client.
18:03
You could do that with multiple clients. So with Pop, if you download your mail on one particular machine now that may only exist on that machine. It's no longer on the server. Thigh map
18:14
exists in both places until you delete it on your one of your machines and deleted on the I'm app server.
18:22
No, the very early form of what now we take for granted in an enterprise environment with Microsoft Outlook. Where,
18:29
where if you're in exchange environment with Microsoft Exchange, you see the same male and Web mail that you see in your outlook client that you'd see
18:37
anywhere you'd log in.
18:38
I'm map is the same principle, but before outlook was around.

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