AWS EC2 instance security groups

 https://stackoverflow.com/questions/44234374/aws-what-does-0-0-0-0-0-and-0-mean

1) By default in AWS EC2 instance security group, or any network, outbound (outgoing connection request) is always allowed

2) However, in AWS EC2 instance security group, inbound rule is any source of connection request to any port is not allowed.

Each desired TCP port such as 80(http), 443(https) need to be opened, and source IP of request need to be specified

.0.0.0/0,::/0 - Means source can be any ip address, means from any system request is accepted, 0.0.0.0/0 represents ipv4 and ::/0 represents ipv6.