Create a network Topology Setup in such a way so that System A can ping to two Systems System B and System C but both these systems should not be pinging each other without using any security rule e.g. firewall etc.

By default, systems can ping each other in the same network.

Here’s an environment has been set in such a way that:

→ System A can ping system B and system C.

→ System B and System C can ping System A

→System B can't ping System C and vice versa.

Assigning I.P manually to System A

Assigning IP manually to System B

Assigning IP manually to System C

All the 3 systems have the same routing table after assigning them IPs manually :

Adding a rule in the routing table of system A.

Adding a rule in the routing table of system B.

Adding a rule in the routing table of system C.

Pinging to system B from system A (pinging)

Pinging to system C from system A (pinging)

Pinging to system A from system B (pinging)

Pinging to system C from system B (not pinging)

Pinging to system A from system C (pinging)

Pinging to system B from system C (not pinging)

Conclusion:

System A is pinging system B and system C successfully. Whereas system B & system C unable to ping each other.

Basically for pinging, data packets are generated and traversed from one system to another. So we edited the routing table in such a way that data packets will be generated from system A for both system B & System C, but system B & system C will generate data packets only for system A. It was possible as netmask decides the range of IPs that come under the same network.

By setting the netmask as 255.255.255.252 for system A, it can ping 4 IPs in its range. We changed the IPs such that system B & system C come under the network of system A, but system B & system C do not belong to the same network as their netmask is set to 255.255.255.254 their network contains only 2 IPs.