networking

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Hooray for the Sockets Interface
2 months ago
- Version 4.2 of the Berkeley Standard Distribution (BSD) UNIX, released in 1983, introduced the BSD sockets networking model, marking a pivotal moment for online services.
- The initial distribution was on tape via mail, reflecting the era's limited network infrastructure, which relied on slow dial-up connections and lacked common protocols.
- Sockets reused the UNIX file descriptor abstraction, making network access simple and consistent, and enabling rapid development of tools like FTP, Telnet, and SMTP.
- Despite initial bugs and limited ARPANET access, sockets became the standard over AT&T's STREAMS, driven by legal disputes and early adoption by companies like Sun Microsystems.
- Sockets ultimately led to the widespread adoption of TCP/IP and UDP, becoming the foundation for modern network programming, with even newer protocols like QUIC relying on them.
Twitter
2 months ago
- Twitter serves as a high-value information source, particularly within curated subcultures like tech, startups, and AI/ML.
- Key system features include user profiles, following, tweeting (280 chars), liking, replying, retweeting, and blocking.
- Emergent properties include middle-distance connections, user-driven curation through following and blocking, and conversational short-form discourse.
- Quality signals and 'pulling in' effects create a flywheel where interesting content attracts more high-quality users.
- Benefits include job offers, real-life networking, and easy access to influential people via DMs.
- To use Twitter effectively, set up a distinctive profile, curate followers from top accounts, and join conversations with insightful replies.
- Post regular 'exhaust' from real-life activities and observations, aiming for at least once daily, while avoiding negativity and over-retweeting.
- When a post goes viral, mute notifications to protect attention span and sanity from low-quality comments.
- The ultimate goal is to build a network of a few dozen high-quality connections for meaningful interactions.
Some brief notes on making ethernet cables - Bert Hubert's writings
2 months ago
- Avoid crimping Ethernet cables if possible; buy pre-made cables to save time and effort.
- Use high-quality tools and appropriate connectors; avoid reusing old or bendy crimping tools or CCA cables.
- When pulling cables through tubes, use a thin, flexible cable puller and secure the UTP cable firmly.
- For solid Ethernet cables, use tool-less keystone connectors instead of standard RJ45 plugs, as they work better and are easier.
- Keystone modules may require a punchdown tool; verify compatibility before purchase.
- Expect to use patch cables with keystone connectors to connect actual devices.
- The author found keystone connectors successful on the first attempt after weeks of failed crimping efforts.
KPN Interactieve TV zonder Experia Box - Bert Hubert's writings
2 months ago
- KPN Interactive TV requires a Set Top Box (STB) that needs multicast TV service (VLAN 4), normal internet (PPPoE on VLAN 6), and an IGMP proxy.
- To bypass the Experia Box, you need a managed switch with VLANs and a Linux computer (e.g., Raspberry Pi) to act as a TV router.
- The STB must get DHCP with option60 'IPTV_RG' on VLAN 4, and NAT is required for its private IP address.
- Normal internet for the STB can be provided by any DHCP server giving DNS and default route.
- An IGMP proxy (igmpproxy) must run to forward multicast subscription requests from the STB's local VLAN to the upstream VLAN 4.
- It is recommended to put STBs in a separate VLAN (e.g., VLAN 44) to avoid multicast flooding WiFi.
- The setup involves configuring VLANs, a DHCP server (udhcpd), and iptables for NAT, plus a startup script in systemd.
- Manual steps include modifying /etc/dhcpcd.conf, /etc/dhcp/dhclient.conf, /etc/udhcpd.conf, and /etc/igmpproxy.conf.
- A startup script (kpn-tv.sh) creates VLAN interfaces, sets IP addresses, starts dhclient, igmpproxy, and udhcpd.
- The article warns about SD card corruption and suggests having backup Raspberry Pi or SD card.
New 10 GbE USB adapters are cooler, smaller, cheaper
2 months ago
- New RTL8159-based 10G USB 3.2 adapters are smaller, cooler, and cheaper than Thunderbolt adapters.
- Full 10 Gbps speed is only achievable with a USB 3.2 Gen 2x2 (20 Gbps) port; other ports yield around 6-7 Gbps.
- The $80 WisdPi adapter is half the price of Thunderbolt alternatives but requires the right USB port for maximum performance.
- On Macs, the adapter works without extra drivers but incorrectly reports 2500Base-T; on Windows, a Realtek driver download is needed.
- For most users, 2.5 Gbps or 5 Gbps adapters offer better value, being cheaper and often sufficient.
- Thermal performance is excellent—the adapter stays cool (42.5°C) unlike hot Thunderbolt adapters, and uses low power (0.86W at USB 2).
- Cheaper alternatives are available on AliExpress, and PCIe versions bypass USB port limitations on desktop PCs.
Solod 0.2: Networking, new targets, friendlier interop
2 months ago
- Solod v0.2 introduces a net package supporting TCP, UDP, and Unix domain sockets with Go-like API but without goroutines.
- New compilation targets include 32-bit platforms, WebAssembly (WASI), and freestanding bare-metal mode.
- C interop improvements include `//so:volatile`, `//so:thread_local`, `//so:attr` directives, type aliases, and numeric C types in `so/c`.
- Deadlines (SetReadDeadline, etc.) are added for blocking I/O; concurrency is still planned for future releases.
- Additional stdlib packages: `encoding/hex`, `uuid`, and arena memory management optimization.
- Diagnostics enhancements: `--track-source` for So source locations and optional `--check-nil` for nil-pointer checks.
Kaizen #4: Overhauled Homelab
2 months ago
- The author overhauled their homelab after moving to a new house, transitioning from a Zimaboard with NixOS to a more powerful HPE DL380 Gen10 server running Debian.
- They improved networking by installing Ubiquiti UniFi gear (UCG Ultra, three U7 Lite access points) and running Ethernet cables throughout the house, including to the garage, overcoming challenges like moving the fiber inlet to the attic.
- The new setup includes services like Jellyfin for media, Immich for photos, Syncthing for file sync, qBittorrent for downloads, Docker management via Dokploy, and monitoring with Uptime Kuma, Beszel, and Grafana/Loki.
- The old Zimaboard will be repurposed as a backup machine with Restic, and the author plans to add a GPU for local LLMs and explore VLANs in the future.
Designing an Ethernet Switch ASIC
2 months ago
- The author built the world's first open source switch ASIC, expected back from fabrication in mid-November.
- Open source networking ASICs are rare; most open source silicon projects focus on RISC-V SoCs, not networking equipment.
- The switch is a 3-port, full-duplex, 100 Mbps, cut-through, unmanaged Ethernet switch due to constraints on pins, area, and ease of use.
- Design constraints include limited pins (8 I/O, 8 output, 8 bidirectional) and die area, forcing the use of an external PHY chip (Microchip LAN8720A) via RMII interface.
- The switch uses a 4-entry address table with TTL-based aging (300 seconds) and a replacement policy for new MAC learning.
- FPGA emulation revealed that the switch works but 100 Mbps is too slow for large data transfers like SSH with GUI forwarding.
- The switch is part of the 'Coffee Shop' family of open source networking IP, including coffeepot, teapot, and coldbrew ASICs.
- Future plans include scaling to a full chip with 8 ports and implementing a content-addressable memory (CAM) for larger address tables.
HomeLab #1: MikroTik as a Home Router
2 months ago
- Setting up a homelab begins with proper networking; MikroTik L009UiGS-RM is chosen for multiple Gigabit Ethernet ports and PoE capabilities.
- Before configuration, identify ISP setup: authentication method (IPoE or PPPoE) and IPv4 type (public vs. private/CGNAT).
- For PPPoE with VLAN, clone ISP router's MAC address on MikroTik's WAN port and create VLAN interface before PPPoE client setup.
- WiFi management uses separate wAP access point with PoE; RouterOS CAPsMAN centralizes configuration for multiple access points.
- Bufferbloat causes latency spikes during network saturation; implement FQ-CoDel queue discipline at 90-95% of line rate to reduce delays.
BYO NOS: Building a maintainable, SRE-friendly switch
2 months ago
- The author previously used an Arista 7050QX2-32S switch, which is nearing end of life, and sought alternatives due to the vendor's unique support for third-party daemons like BIRD.
- Whitebox switching options like SONiC and DENT were considered; DENT uses switchdev for Linux kernel integration, allowing hardware offload similar to Arista.
- A Mellanox SN2010 switch with Spectrum ASIC was selected for its switchdev support, and Debian was installed after configuring the kernel and udev rules for mlxsw.
- Breakout cables were configured using devlink, and network interfaces were managed with systemd-networkd, though it required verbose configuration.
- Routing challenges included limited ASIC route capacity; solutions involved resource reallocation, ECMP default routing, and route compression via a custom Go tool to reduce routes from ~1.2 million to ~92k.
- ACLs were implemented using TC (Traffic Control) with features like blocks and chain templates to optimize hardware offload and resource usage, including actions like goto, trap, and pedit.
- Egress control was achieved through VLAN rewrites and additional routing tables, allowing traffic steering based on DSCP values without reconfiguring the router.
- Monitoring utilized standard tools like Node Exporter and hsflowd, with custom exporters for devlink metrics, ensuring comprehensive system and dataplane visibility.
- Maintenance is simplified as the system runs on Debian with upstream tooling, enabling easy updates and config management, exemplified by a quick kernel update for security vulnerabilities.
TLS certificates for internal services done right
2 months ago
- Using split-horizon DNS allows the same domain to resolve to public or private IPs based on client connection.
- Setting up a WAF (e.g., via nginx) blocks traffic from public internet, adding security beyond DNS.
- Automating certificate renewal with acme.sh and cron jobs ensures ongoing TLS without manual intervention.
- Using SAN certificates enables multiple subdomains under one certificate, avoiding wildcard security risks.
How to ask for help from people who don't know you
3 months ago
- Asking for help is a skill, not an innate attribute; the key principle is to put yourself in the other person's mind.
- To make someone want to help, demonstrate you are worth helping by showing proof of work, personal connections, or institutional credibility, with proof of work being the strongest.
- Explain context concisely by connecting it to what the other person already knows, using borrowed attention wisely.
- Make requests easy to accept by reducing costs, being specific, low-friction, and bounded in scope.
- Make it easy for the other person to say no to avoid pressured yeses and build genuine, willing help that fosters relationships.
- Never lie in requests, as dishonesty undermines credibility and any chance of a positive response.

networking

Hooray for the Sockets Interface

Twitter

Some brief notes on making ethernet cables - Bert Hubert's writings

KPN Interactieve TV zonder Experia Box - Bert Hubert's writings

New 10 GbE USB adapters are cooler, smaller, cheaper

Solod 0.2: Networking, new targets, friendlier interop

Kaizen #4: Overhauled Homelab

Designing an Ethernet Switch ASIC

HomeLab #1: MikroTik as a Home Router

BYO NOS: Building a maintainable, SRE-friendly switch

TLS certificates for internal services done right

How to ask for help from people who don't know you