// BLOG · PAGE 5 OF 8
ALL POSTS · PAGE 5 / 8
NAT rewrites addresses; connection tracking is the memory that makes the rewrite reversible. Together they're why the internet survived IPv4 exhaustion — and why your idle SSH session dies, your table overflows, and P2P needs hole-punching.
Every packet's last hop is decided not by routing but by a 1982 protocol with no authentication, a cache with quirks, and failure modes — gratuitous ARP, proxy ARP, spoofing — that explain a shocking fraction of 'the network is weird' tickets.
Signals interrupt your program between any two instructions and run your handler in the wreckage. Why almost everything is illegal inside a handler, what async-signal-safe really means, and the self-pipe/signalfd escape hatches.
The fastest malloc is a pointer bump; the fastest free is resetting one offset. Arenas trade individual deallocation for speed, locality, and the death of use-after-free within a lifetime — a trade half your workloads should take.
A powered-off machine has no OS, no IP stack, no running software — yet a single crafted broadcast frame boots it. How the NIC stays half-awake watching for its own MAC, why WoL is a layer-2 trick, and the homelab plumbing to make it reliable.
Fixed windows let 2x through at the boundary, token buckets are three lines of arithmetic, and the distributed version is a consistency problem wearing an ops costume. The algorithms, their failure modes, and what to return when you say no.
malloc has a supplier: the kernel's own allocators. The buddy system deals in power-of-two page blocks and fights fragmentation with math; the slab layer turns pages into typed object caches. Between them, every allocation on your machine.
Half of all confusing C build errors — undefined reference, multiple definition, static initialization order — are linker concepts wearing compiler costumes. Symbols, relocations, and the archive rule that surprises everyone.
C++ virtual calls, Linux file_operations, and Go interfaces are the same machine code: load a pointer, call through it. What a vtable really is, what an indirect call costs, and how devirtualization claws it back.
A superloop is the right architecture more often than embedded tutorials admit — until the day it isn't, and you need preemption, priorities, and blocking. What FreeRTOS actually buys you on an ESP32, and what it costs.
Binary search loses to linear scan on small arrays. Hash maps lose to sorted vectors. Big-O tells you how algorithms scale, not which one is faster — and on modern hardware the gap between those two questions is enormous.
Between your server and each user sit browser caches, CDN tiers, and shared proxies you don't operate — all obeying Cache-Control headers you may have set by accident. The freshness/validation model, and the headers that cause incidents.