cybersecurity, networking, linux — going deep on the fundamentalshttps://pgah.github.io/https://pgah.github.io/posts/how-databases-work/https://pgah.github.io/posts/how-databases-work/A database isn't a smarter file. It's a system built around one promise — your data survives, stays consistent, and can be found fast — and everything from indexes to transactions exists to keep that promise.Sun, 23 Aug 2026 00:00:00 GMThttps://pgah.github.io/posts/how-git-works/https://pgah.github.io/posts/how-git-works/Most people learn Git as a sequence of commands to memorize. Underneath, it's a content-addressable object store with four object types and a graph of commits. Understand that, and the commands stop being magic.Thu, 20 Aug 2026 00:00:00 GMThttps://pgah.github.io/posts/linux-networking-iptables-and-netfilter/https://pgah.github.io/posts/linux-networking-iptables-and-netfilter/Every packet that touches a Linux box passes through a kernel framework most people never see directly. iptables is the interface. netfilter is the machine underneath it — and it's why your server's firewall, NAT, and connection tracking all live in the same place.Mon, 17 Aug 2026 00:00:00 GMThttps://pgah.github.io/posts/how-ipv6-works/https://pgah.github.io/posts/how-ipv6-works/IPv6 has been the official answer to address exhaustion since 1998, and most of the internet still runs without it. It isn't IPv4 with longer addresses — it's a different set of assumptions about how hosts find each other.Fri, 14 Aug 2026 00:00:00 GMThttps://pgah.github.io/posts/how-systemd-works/https://pgah.github.io/posts/how-systemd-works/PID 1 isn't just the first process — it's the supervisor, the dependency manager, and the security boundary all at once. This is how systemd manages the transition from a running kernel to a functioning system.Tue, 11 Aug 2026 00:00:00 GMThttps://pgah.github.io/posts/how-nat-works/https://pgah.github.io/posts/how-nat-works/IPv4 has around four billion addresses. The internet has more devices than that. NAT is the workaround that bought the internet thirty years — and it shapes every connection you make from home.Wed, 05 Aug 2026 00:00:00 GMThttps://pgah.github.io/posts/linux-processes-and-signals/https://pgah.github.io/posts/linux-processes-and-signals/A program sitting on disk does nothing. A process is what the kernel creates when it decides to run one — and signals are how the system talks to it while it does.Wed, 05 Aug 2026 00:00:00 GMThttps://pgah.github.io/posts/linux-users-and-groups/https://pgah.github.io/posts/linux-users-and-groups/The permission bits on a file say who can read it. But 'who' in Linux is a number — and the rules for how that number can change while a program runs are where most privilege escalation lives.Wed, 05 Aug 2026 00:00:00 GMThttps://pgah.github.io/posts/how-http-works/https://pgah.github.io/posts/how-http-works/Every web page you load is a conversation in plain text: a request, a response, and a stack of headers doing the real work. It's simpler than you think and more consequential than it looks.Sat, 01 Aug 2026 00:00:00 GMThttps://pgah.github.io/posts/how-tcp-ip-works/https://pgah.github.io/posts/how-tcp-ip-works/Every connection you make is built on two protocols working together — one that routes packets across networks that don't know each other, and one that turns an unreliable stream of packets into an ordered, guaranteed conversation.Fri, 31 Jul 2026 00:00:00 GMThttps://pgah.github.io/posts/linux-file-permissions/https://pgah.github.io/posts/linux-file-permissions/The permission model in Linux dates to early Unix and is one of the most misunderstood parts of the system. The gaps in that understanding lead directly to the most common privilege escalation paths.Sun, 26 Jul 2026 00:00:00 GMThttps://pgah.github.io/posts/how-dns-works/https://pgah.github.io/posts/how-dns-works/You type a name. The network only speaks in numbers. Between those two facts is a distributed system running on thousands of servers with no central authority, and it's queried before every connection you make.Sat, 25 Jul 2026 00:00:00 GMThttps://pgah.github.io/posts/how-tls-works/https://pgah.github.io/posts/how-tls-works/The padlock in your browser isn't decoration. It's the result of a cryptographic handshake and understanding it changes how you think about trust, identity, and what 'secure' actually means.Mon, 20 Jul 2026 00:00:00 GMThttps://pgah.github.io/posts/how-ssh-works/https://pgah.github.io/posts/how-ssh-works/Not just a remote terminal. A cryptographic protocol and understanding it changes how you think about trust, identity, and what 'secure' actually means.Sun, 12 Jul 2026 00:00:00 GMThttps://pgah.github.io/posts/the-architecture-of-linux/https://pgah.github.io/posts/the-architecture-of-linux/Not the commands. The actual system — what it is, how it thinks, and why it works the way it does.Tue, 30 Jun 2026 00:00:00 GMThttps://pgah.github.io/posts/intro-to-networking/https://pgah.github.io/posts/intro-to-networking/How data actually moves. What the OSI model really means. And why you can't skip this.Sun, 28 Jun 2026 00:00:00 GMThttps://pgah.github.io/posts/intro-to-cybersecurity/https://pgah.github.io/posts/intro-to-cybersecurity/Where to start, what actually matters, and the mistakes I made so you don't have to.Fri, 26 Jun 2026 00:00:00 GMT