Systems Cheatsheet
A quick-reference guide for systems and networking.
Networking Layers
OSI vs TCP/IP, encapsulation, and an interactive zoom that unwraps a single HTTPS request from bits on the wire down to the HTTP payload.
TCP Handshake
The three-way handshake that establishes a reliable byte stream — segments, flags, state transitions, and teardown.
TLS Handshake
Authentication, key exchange, and cipher negotiation — TLS 1.3 flow, certificate verification, and 0-RTT resumption.
Linux Binary Execution
From ./prog to main() — execve, ELF layout, ld.so, the startup path, and exec-time security.
Linux Signals
How an async notification becomes a handler call — generation, pending sets, kernel-exit dispatch, sigaction flags, and async-signal safety.