Pingability between systems in Network Topology Setup

Objective

Create a Network Topology Setup such that System A can ping to both System B and System C. Also, both these systems shouldn’t ping to each other unless any security rule like firewall/firewalld is mentioned.

Project Understanding

System A → 192.168.56.206

System B → 192.168.56.209

System C → 192.168.56.210

OS Used → RedHat 8

Let’s check if each system is pinging to each other

System A to System B & System C
System B to System A & System C
System C to System A & System B
  • Let’s enable ping operation within the firewalld in both System B & System C. First of all firewalld should be enabled on both systems and the command for the same is mentioned below:
systemctl enable firewalld --now
  • In order to enable ping operation within the same, it should be added as a rule in firewalld and could be done by using the command below:
firewall-cmd --permanent --add-service=ssh
  • Complete firewalld configuration could be obtained using the command mentioned below
firewall-cmd --list-all
Under services, ssh is specified which indicates that ping has been enabled within firewalld

After enabling ping operation within firewalld, check if both systems are pinging to each other.

System B to System C
System C to System B

Let’s understand the command that could be used to disable ping operation in both the systems as soon as firewalld is stopped. The command used is mentioned below:

  • For System B:
systemctl stop firewalld && iptables -A INPUT -p icmp --icmp-type echo-request  -s <System_C_IP_Address> -j DROP
  • For System C:
systemctl stop firewalld && iptables -A INPUT -p icmp --icmp-type echo-request  -s <System_B_IP_Address> -j DROP

After executing the above mentioned command, both the systems are unable to ping to each other

System B unable to ping to System C
System C unable to ping to System B

Let’s check if System A is able to ping to both System B & System C

From the above image, System A is able to ping to both System B & System C even though System B & System C are unable to ping to each other.