Port reachability within subnet (telnet)

Steps to Create Security List

1. We try to run telnet with ip address 142.251.129.174 for checking port connectivity with port range 443 but we can't connect with it because in our server telnet not installed.

2 Now we first install the telnet by going to root by using the command "sudo su - root" and after this use command "yum install telnet"

sudo su - root

yum install telnet

As we see we are not able to download or install the telnet software because we have only Egress specific rule for only for ping as ICMP. for download the telnet software we need to add new rule in egress and set protocol as TCP.

3.here in destination CIDR put 0.0.0.0/0 and in IP Protocol set as "TCP" to allow all ports and added egress rules

4.After adding we can run command again to install telnet and this time we successfully download the software and also intall it.

5. Now again we try to run command telnet to check the port connectivity. and this time we connect with port successfully

6. Now we try to make it restrictive, in destination CIDR put 0.0.0.0/0 and in IP Protocol set as "TCP" and in Destination port range as 443.

Server to Server port connectivity by telnet

Here we try to check port connectivity of target ip address 10.0.0.54 with port range 22, but we can't connected. Because here ingress security rules not available.

So first here we add ingress rule in security list

Now we can add egress rule in security list

Now we try to connect with telnet and this time we successfully connected with telnet