EC2 & Compute

EC2 is full-control virtual machines, ECS is AWS-native managed containers, EKS is managed Kubernetes for portability, and Lambda is serverless functions for short event-driven work.

Logins live in the auth log and in last/lastb, current sessions in who, everything else under /var/log and journalctl, and the EC2 console system log works even when SSH does not.

Walk the packet's path layer by layer: instance health, Security Group, NACL, route table and internet gateway, public IP, key pair, and OS firewall, and the drop point reveals the fix.

EC2 is a rented virtual server, the family picks what it is good at, and launching it means choosing its image, size, key, firewall, network, permissions, and disks.

The public key lives on the instance and the private key stays with you; Linux uses the private key directly over SSH, while Windows uses it to decrypt the Administrator password for RDP.

RDS is a managed relational database where AWS does backups, patching, failover, and replication for you, while a database on EC2 means you do all of that operational work yourself.

A private instance has no public IP, so you reach it via a bastion, SSM, or VPN, and you give it outbound-only internet through a NAT Gateway that blocks all inbound.