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overlay-vpn

mesh VPN / overlay network

WireGuard, Tailscale

SystemTechniques · 13Primitives · 54 overlay-vpn Config distributiondistributed · medium: A control plane pushes versioned resource changes over long-lived streams; each node validates, ACKs or NACKs and keeps its last good copy, so a bad change stops at a canary.›Deterministic simulation testingdistributed · medium: Run the whole system in one thread under a seeded scheduler with simulated network, disk and clock, so every failure replays from its seed.›Primary-backup replicationdistributed · medium: One node orders all writes and ships them to standbys; the acknowledgement rule (none, one, all) sets what a crash loses, and an external arbiter decides who takes over.›NAT traversal (STUN, ICE, TURN)media · medium: Learn your public address with STUN, swap candidate addresses over signalling, test pairs with ICE checks, and fall back to a TURN relay if no direct path works.›Coverage-guided fuzzingsecurity · medium: Mutate inputs, run an instrumented target, and keep any input that reaches a new code edge; feedback turns blind guessing into incremental search.›Point-in-time recoverystorage · medium: Periodic base backups plus a continuously archived change log let you rebuild the state as of any instant, then branch from there.›Delta debuggingcompilers · medium: Ddmin minimization of failing inputs or change setsHdr histogramdata-structures · low: Log-linear bucketed histograms with bounded relative error for latency percentilesProcess supervisionhardware-os · low: A parent process starts services, reaps their exits and restarts them under a delay and burst-limit policy, then stops them with SIGTERM before SIGKILL.›Longest prefix matchnetworking · low: IP prefix lookup structures (DIR-24-8, Poptrie, LC-trie) for routes, ACLs and geo-IPPath mtu discoverynetworking · low: PMTUD and PLPMTUD to size packets for tunnels without fragmentationTun tap devicesnetworking · low: Userspace virtual network interfaces for VPNs and tunnelsAEAD (AES-GCM, ChaCha20-Poly1305)security · low: Authenticated encryption that encrypts and detects tampering in one call; the only kind of symmetric encryption you should use.›Authorization models (RBAC, ABAC, R…security · low: How to decide who may do what to which object; roles for coarse rules, relationships for sharing, and checks on every object.›Cryptographic hashes (SHA-2, BLAKE3)security · low: Collision-resistant fingerprints of data; SHA-256 for interoperability, BLAKE3 for speed, HMAC/HKDF for keyed uses.›ECDH key exchange (X25519, P-256)security · low: Each side multiplies the other's public curve point by its own scalar and both get the same point; always validate the peer key and run the result through a KDF.›Mutual TLSsecurity · low: TLS where the client also proves a certificate key, so every connection carries a verified, rotatable machine identity.›Noise protocolsecurity · low: Noise framework handshakes (IK, XX): DH patterns, chaining keys, transport ciphersOAuth 2 and OpenID Connectsecurity · low: Delegated authorization (OAuth 2) and login on top of it (OIDC); use authorization code + PKCE for every user-facing client.›Replay protection windowsecurity · low: A highest-seen counter plus a bitmap of the last W numbers rejects duplicates and stale messages in O(1) with a few hundred bytes of state.›Graceful drainingsystems · low: On a termination signal, stop taking new work, finish in-flight work until a deadline, tell clients to reconnect elsewhere, then exit; clients resume from a token.›Delta encodingcompression · low: Store differences between consecutive values instead of the values, turning sorted IDs, timestamps and counters into small numbers that pack into few bits.›Message sequence numbersdistributed · low: A per-stream counter on every message lets the receiver detect loss, duplicates and reordering, ack cheaply and resume after reconnect with "send from N".›+ 6 more techniques+ 38 more primitives

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