Explained: AWS ENIs (Elastic Network Interfaces)

Your production database server starts throwing errors at 2 a.m. The on-call engineer spins up a replacement instance, and now the scramble begins: update the DNS record, wait for the TTL to expire, reconfigure the firewall rules that were pinned to the old private IP, and hope every downstream service notices the change. Twenty minutes of downtime, most of it spent chasing a network identity that was welded to a machine that no longer exists. Th… Read More

Architecture: How EC2 Works

You spin up an instance, SSH in, and it just works. You get a Linux prompt, a fixed amount of memory, network access, and a disk. Where that instance actually runs, what it shares with other instances, how your keystrokes travel from your laptop to that shell — all of it is invisible. That invisibility is the product. But understanding what is underneath it changes how you design for failure, choose instance types, tune networking, and debug the… Read More

Explained: Bastion Server

Bastion Server Your database server should never be one misconfigured security group away from the public internet. Yet in many infrastructure setups — especially early-stage ones — that's exactly what happens. Private servers get assigned public IPs. SSH ports get opened to 0.0.0.0/0 . Engineers take shortcuts to move fast, and the exposure quietly accumulates. A Bastion Server is one of the simplest, most effective patterns to prevent this. The… Read More