Network Topology

NETWORK TOPOLOGY

In this article, we will create a Network Topology in which System A can be able to ping to two Systems → System B and System C, but both these Sytems System B and System C are not able to ping each other, without using any security rule e.g firewall, etc.

Before moving onto the practical refer to some of the basics of networking from my previous article here 👇

Create a Setup so that you can ping google but not able to ping Facebook from the same system

Let’s do the practical,

For this practical, I'm using 3 Redhat VM’s which are connected to switch in the same system.

rhel8 systems

For this practical in every VM settings → in the network → select as ‘Host-Only Adapter’.

selecting network

We are using the same network so that every system connected to the same switch.

Now start the systems and do the below steps:

System A

In system A, I have changed into private IP by using this command:

# ifconfig enp0s3 192.168.50.1/24

enp0s3 → network card name and IP is set to 192.168.50.1 with netmask → 255.255.255.0

setting a private IP for System A

create a new routing rule in System A by using this command

# route add -net 192.168.50.0/30 enp0s3

with this rule, system A will only create packets for the IP’s 192.168.50.0, 192.168.50.1, 192.168.50.2, 192.168.50.3

To check the routing table use the below command

# route -n

routing table of System A

System B

In system B, I have changed into private IP by using this command:

# ifconfig enp0s3 192.168.50.2/24

setting a private IP for System B

Create a new routing rule in System B using this command

# route add -net 192.168.50.0/31 enp0s3

By this rule, only 2 IP’s are allowed 192.168.50.0 and 192.168.50.1 as the netmask is set to 255.255.255.254

routing table of System B

System C

In system C, I have changed into private IP by using this command:

# ifconfig enp0s3 192.168.50.3/24

setting a private IP for System C

Create a new routing rule in System C using this command

# route add -net 192.168.50.0/31 enp0s3

By this rule, only 2 IP’s are allowed 192.168.50.0 and 192.168.50.1 as the netmask is set to 255.255.255.254

routing table of System C

Now,

Let’s ping, here this is System A

System A

As you can see System A can ping System B and System C

Here is System B

System B

As you can see System B can ping System A but not to System C

Here is System C

System C

As you can see System C can ping system A but not to System B

This how we can create this kind of Network Topology without stoping any firewall rule or other security rule.

For any queries, you can ask me here in the comments.

Thank You 😇