In the section we're going to talk about the access control lists.
Let's go with the ACL or will a c as access lists are a set of commands which are grouped together to
filter the packet that enters or leaves to an interface.
They control the flow of traffic in their work and provide security for network access access lists
are implemented sequentially as a permit or deny statement to inbound or outbound of interface and used
for also different purposes such as for example maybe a rough map or something like that.
There are two types of access lists and they are standard or extended.
And they can be used with numbers or named format.
Please pay attention that each ACL must have a permit statement because there is an implicit denial
rule at the bottom of each ACL.
That's the key point.
Anywhere you see an example for the number access list which are permitting some networks.
And here's our configuration access list and the number.
Then permit or deny statement and we're using and network and we are using air field named Wild Cards
which we're going to exit mine later.
All access lists must be identified by a name or a number.
As I told you in the first slide and then the access lists are more common than then numbered access
lists because you can specify a meaningful name that is easier to remember and associate with that task.
You can reorder statements in or add statements to named access lists and name the access lists support
the following features that are not supported by a number to access such as IP options filtering noncontiguous
ports or TCAP flic filtering.
All right.
Here is how we can configure named access list to configure a name access list.
We are typing i p access list command and we're choosing.
If we're going to use an extended or if we're going to use a standard access that most of the time in
this Exxon-Mobile we're using standard and I pay access list and the standard configuration.
And we are writing the name of our access this thing here and as you can see in here under the access
this month we are denying or permitting to sign statements.
OK let's go ahead with the wild card mask.
What mask is a mask of bits that indicates which parts of an IP address are available for an examination
and determines what IP addresses should be permanent or denied in access control lists.
What kind of mask has a reverse logic logical subnet mask as 0 in the wild card mask means to focus
to that bet while as one means to ignoring the to when if you see is zero on the summer mask answer
on the current mess that means we need to take care we need to focus a little bit but if we're seeing
one that means we need to ignore that bit.
OK I'm going to show you an example as well.
In this access list we're seeing an accidental statement and this access list is saying and access this
didn't number access as one per minute wandered in some way to that 16 0 0 with that wild card massacre
of 0 0 255 255.
So what that means here is the network the and the here is the answer here is the wildcard mask what
that so you is if we're using zero that means we need to focus to relate to pets.
All right.
As you can see in here I have a zero and I need to focus to one hundred and seventy two in here.
We're another zero and we need to focus to 16 on the last two bits we have just once for the 2:55 as
you can see in the binary version.
And that means we need to ignore that bit.
So this wildcard mask means for cursor everything starting with the 100 and so and if for seven to that
16
and so that means we are permitting everything starting with they wandered 70 to that 16 for example
winers.
So into that 16 1.5 maybe Whatever were you want let's go with the World Cup mask example too.
And we have another configuration access list 50 per minute this time 192 100 and 68 8.00 outcome mask
of 0 0 0 255 which means a zero.
And here is the wildcard mask
which means we need to focus the first three portions and we don't care the last portion because we
have continuous ones in a year.
That means this access list permits everything starting with the ones that 90 to 100 and sixty eight
that's a lot.
For example oh that's strong strong.
That would be something like that.
And we can give an example like
63 5:06 to other Durnford for AM.
That's an arbitrarily OK let's go with the standard IPV for access lists standard access lists perform
packet filtering based on sound source sudras and must be implemented to other which is the closest
to the destination address for official see numbers where it wants 99 and 1000 and 300 and one thousand
nine hundred ninety nine.
These range are used for standard access this configuration and this access lists are applied to interfaces
by IPX this group command.
As you can see in here there is an standard access this configuration we're getting into the conflict
mode first then we are typing access lists and the number of access list and the permit or deny and
The relate to network.
Then we are getting into the interface mode and via implementing this access list.
Two are related interface which means for example we Heraldo in here we are faster than 0 0 and Fester's
0 1 and we are implementing this IP access group to inbound.
This would be fifth the to inbound.
Which means really we are implementing to this we are implementing this access this to this direction.
Let's go hat in this example we have another standard access list access list for in the first month
we are denying the Sen. 41 zeros Zeeuw.
I'm sorry 20 0.
That means everything beginning with this 10:41 20 and something like that.
If the second statement we're poor meaning the host then 12:56 to any that 5 in here R.K. access list
rules are implemented.
The international security issue as you as I told you in the first statement we're also denying discipled
this as you can see.
So the traffic will be blocked even if we type discipled this with a permit statement in here as is
consider the New Year there there's a conflict between two rules in this example.
Let's take a look at another configuration example on a topology now on rather one.
We are defining an access list standard access list and we are denying the host to that 5.
OK.
This guy will be denied.
And we're permuting any other traffic.
Ok then we are getting into the interface mode interface gig 0 0 which is here and we are implementing
the access list to inbound.
That means in that in this direction.
So PC to will be denied.
For example what if it wants to communicate with the PC Wan to that the standard access list configuration
for example as you know access list one denying the host 2.6 for this example which is the right thing
then the access list one is Poorman thing.
Any we are permitting any other things.
So if you want to added this configuration we are typing the show Oxus list command and we are seeing
the sequence number in here as you can see skirt's number 10 is denying this holes and sequence number
20 is permitting anything else.
So if you want to edit it we are typing.
I pay taxes and standard one then note 10 which means we are letting this through.
And we are typing in denying holes down 41 to that five maybe.
All right.
This is how that is to provide the access list to where the standard Access is configuration.
We can use the show access lists command and we can also use the Sharpy interface and the related interface
command.
And we can see that if there is an embargoed or outbound access was applied to that interface.
Let's go ahead with the extended IP for access lists extended access list performs packet filtering
based on Sarsour address destination address protocols and the port numbers Itzig.
It's good that the extent of the ACLU are implemented rather which is closest to source address for
f and c and here's the range that we can use for the extended access lists extends access lists are
Pletcher interfaces.
BI I picked this group name number in and out statements as well as in the standard access list and
there is the configuration example access lists this time 100 which is in this range as you can see
is the name the TZP traffic which is coming from this sarce and going to this destination for the ports
it Khune to 23 which is the telnet part.
I can also read this statement in here Access is 190 TCAP same thing same thing say it coolant too I
can write the porticos names start protocols names as well directly.
For example telnet for example.
Then the same thing as the standard Access is that I'm getting into the interface mode and am typing
the IP access group number of days sale and inbound or outbound as the direction and here is the same
text as we can see the access list and access number permit or deny the protocols named sources rest
and the wild card of the source then the port operator and source port.
And the answer is destination and destination wild card pool operator and the destination port.
Again you get to it better by this example in here as you can see here with an access list configuration
which is an excellent one in the first stateman access is 100 is permitting the TCAP traffic coming
from
this number by díaz wild card which means everything beginning with these three portions.
And via the net we are permitting this through a big way.
It's going through this horse directly.
I can also use in your sound San Juan one of four with a wildcard mask of 0 0 instead of here.
But I can also use force for simplicity.
HOST The host keyword and the host IP address with an equivalent of W W W port.
OK.
That means actually permit TCAP traffic from this guy from this network to port 80 which is the HTP
port on the host 10 1 1 and 2 or 4 OK.
Let's go ahead with the second.
Is 100 per minute.
IP this guy is permuting the traffic from this network while it's going through this network.
OK.
Permit the traffic for on this network slushed 24 to that network slashed two and four.
OK let's go ahead with this third denied teensy piece ok from the
host this time again as you can see that any year I'm using the one that my 268 that won that one with
the 0 0 0 0 wildcard mask which means actually this IP address I'm focusing all of these bets and the
destination will be what 10 on one to another of to four a cool and to £23 which is town and Port.
OK.
And denying the terminal traffic sourced by this destination is here.
OK let's go with the fourth one in the fourth step.
We're using another D-Nice statement from the this.
Horst to this first there is a missing statement and there may be in here there is a 0 0 0 0 as well
within a cube of to 80 which means air support.
And in the last statement we are seeing and access at least 100 per minute.
IP any any and this any key word means if you want to match all sources or all destinations subs to
the entire source or destination elements of command with keywords any Let's go with another configuration
example.
Create an access list that will per math this subnet for TCAP sessions OK.
Create an access list that will deny telnet sessions to actually these costs for this host.
Create an access list that will permit any IP traffic R.K. access this while wandering one will permit
to TCAP sessions
from this network.
From this subnetwork
to any destination.
OK as you can see here the wildcard mask is 0 0 0 15.
This time for slushed 28 OK Slish 20.
It means 255 2:55 255 and 240 to convert this guy to a wildcard mask we can use 0 0 0 and 55.
OK.
So if we add all these guys to each other the end result will be to worth to you for 255 and 250 five.
OK.
In the second we are writing it denies access is one on one denying TZP from any source.
To the destination was this guy with equal and Port of 23 which means tell that and in the third statement
we are creating an access that will permit any IP address Trevitt which is access this 100 on one permit
IP any Annie.
Here is another configuration example for you.
Arcade's saying as a block just tell that traffic coming from PC one and going to PC to OK this guy
will be our source.
And here will be our destination or other one I'm running an external access list.
Oxus is one or one denied TZP host from PC Wan to PC to with the equivalent of telnet.
And as I told you in our first slide we should have at least one spermine statement for each access
list and I'm writing the access this 100 percent IP any any which is permitting any other traffic from
different from the sky.
And we're also implementing these IP addresses.
I'm sorry this access to the E-Man direction of the first Internet 0 1
25 extended access configuration.
We can use the sure access list command as you can see and we can display them and we can also use your
IP interface and the related interface name as well.
Let's go with the IP version 6 to 8 sales.
We can't just use name.
The ACL for the IP version 6 that works and we have the similar logic with IP version for extended ACL
but any year we don't have any wildcard mask and we are using the IP version 6 traffic filter command
to apply to access list to do later.
The interface is the configuration example and we are type in first I perversions 6 axis lists for this
time and the name of Texas is we have just named a scale for IP version 6 and we are denying more a
host with an IP address of this and with an IP address of this.
And this guy will be our source with the destination of this IP address.
And we are permitting any other traffic and to implement this as safely to our interface.
We are using IP version 6 traffic filter command.
Instead of using IP access group command in RPV for a sales.