AWS

load balancers

• Classic TCP ELB works like TCP proxy. It creates 2 back to back TCP connections for a client connection: one from the client to ELB, the other from ELB to a server instance. ELB security groups need to allow incoming traffic from public internet, and instance security groups need to allow incoming traffic from ELB.

• NLB works like NAT. It keeps a client connection without changing source IP, ports, and sequence numbers. NLB does not have security group. The instance security group need to allow incoming traffic from public internet.

aws cli

who am i:

aws sts get-caller-identity

get instance role and credentials

curl http://169.254.169.254/latest/meta-data/iam/security-credentials