#Networking
VM Sees the Dongle but Has No Internet Without a Windows ECM Driver
After passing a USB LTE dongle through to a Windows VM, the system sees the device but no network adapter appears. The cause is neither the SIM nor port passthrough, but the dongle exposing a CDC ECM interface that Windows has no built-in driver for, along with storage-mode pitfalls and dhclient overwriting the host's resolv.conf.
The NVR Kept Beeping, Then Fell Silent When the Disks Failed
The NVR's all-day beeping was not videoloss as everyone thought. It was ipconflict from cameras using DHCP with conflicting IP addresses. Someone got annoyed and muted the whole unit, so when both disks failed together, there was not a single beep. This article fixes the policy one event at a time through ISAPI.
Registrar and Billing NS Mismatch: Audit All Three Sides First
A debugging log for "Wrong response from the server" when changing nameservers in a billing system, which failed only for domains with leftover glue IP data, followed by a three-way audit of the registrar, billing system, and actual DNS zones before I felt confident changing anything.
Egress Firewall Breaks Domain Checks — Tests as root Pass
The domain order page reported every name as unavailable, even names I made up. The cause was an outbound DROP policy with port 43 missing from the allowed port list after an operating system migration. The trap was that tests as root passed every time. Testing must use the account that actually runs the app.
One Tunnel Is the Only Way In—and a Single Point of Failure
The machine sits behind NAT with no ports open to the internet. Every way in runs through one cloudflared tunnel — web, SSH, and remote desktop. This article covers the four ingress routes I set up, how to read the signs when it goes down, and the trap that keeps the tunnel from starting at boot.
Tell a Broken Link from an ISP Outage Before Restarting Anything
A typical watchdog restarts NetworkManager when ping fails, which is wrong half the time because no internet access may mean the ISP is down, not that the adapter has failed. This article distinguishes three states using nmcli, then escalates from gentle recovery to PCI remove and rescan without rebooting the machine.
Borrowing a VLAN for Windows Tools That Need the Same L2
Many manufacturers' device discovery tools use broadcasts that cannot cross L3, so connecting over a VPN still leaves devices invisible. A solution that leaves switch ports alone is to put a small Windows VM on Proxmox with its interface directly in that VLAN, with pitfalls around vlan-aware bridges, a full thin pool breaking other VMs, and virtio leaving Windows without a network adapter after installation.
Managing Site Switches Remotely with UniFi's Cloud Connector Proxy
My workstation is in a different location from the site, with no VPN and no inbound ports open, but I still need to change VLANs per port, reserve fixed IPs, and track down failing cables. This article explains how Site Manager's connector proxy reaches the legacy API for both reads and writes without requesting a CSRF token, and the discipline needed when holding a key this powerful.
Set VLANs on a Hikvision Switch Using Its Web UI API
A smart managed switch whose Switch ISAPI endpoints return 403 can still be scripted if you inspect what its web UI sends. This article turns that API into a VLAN configuration script with a dry-run before apply, covering the traps I actually hit, including different field names for reads and writes, CCTV mode forcing 10 Mbps, and a calculated PoE load that exceeds the switch's budget.
Using an NVR to Reach Inaccessible Cameras with ISAPI and SDK
The cameras sit behind the NVR's second interface, and none are directly reachable. This article works through what the NVR's ISAPI can actually do, with 26 of 38 tested endpoints working, retrieves CCTV snapshots and RTSP through the NVR, finds when each channel last recorded, and falls back to HCNetSDK through ctypes to read device logs when ISAPI runs out of options.
Auditing CCTV Directly with ISAPI and ffprobe RTSP, Bypassing the NVR
The NVR screen only tells you a camera is online. It does not tell you its model, how old its firmware is, or the actual stream resolution. In this article, I write a script to query ISAPI deviceInfo on each camera directly, then use ffprobe to read values from the actual RTSP stream to build an inventory and check the health of the camera system I maintain.
Planning 2.4GHz WiFi Channels 1/6/11 and Multi-Floor Heatmaps
A five-story building with seven APs per floor needs a 2.4GHz channel plan that avoids overlap both horizontally and vertically. This article covers the 1/6/11 principle, per-floor channel tables, the actual Tx power and RSSI threshold settings, and a Python script that labels floor plans with channels using PIL before a walkthrough survey to create a heatmap.
Inventory Switch and AP Ports with SNMP Walk and MAC Tables
You can build your own Layer 2 inventory without a controller or NMS. Write an SNMP walk with pysnmp asyncio to retrieve sysDescr, ifTable, and the bridge FDB, then convert OID indexes back into MAC addresses to find which device connects to which port on which switch.
Building a Single-Screen Ping Monitor with C++, ImGui and DirectX 11
A small app that pings every device on the network at once and puts the results on one screen. It sends ICMP directly through iphlpapi without calling ping.exe, runs one thread per host, communicates with the UI through std::atomic, renders with Dear ImGui on DirectX 11, and builds with CMake and a single PowerShell script.
Read Device Uptime Without SNMP/SSH/API Using TCP Timestamps
Many IP cameras, door controllers, and embedded devices have no SNMP, SSH, or API for querying uptime. But if they return TCP timestamps, I can read their boot time remotely without logging in even once.
Factory to Cloud Behind NAT: Push Snapshots and a Command Queue
The production machine sits in a LAN behind NAT with no public IP, but the owner wants to view data on a cloud website and make edits from a phone that reach the internal machine — possible without opening ports or setting up a VPN, using push snapshots + an edit command queue + idempotent acks
MDES 2564 Government CCTV Price Limits and a Hikvision PoE BOM
Read the full MDES June 2564 government CCTV reference pricing and basic specifications before setting a budget, then design a Hikvision IP/PoE BOM that meets the minimum specifications, reference price ceilings, 30-day recording retention rule, and requirement to allow at least 3 brands to compete.
Control TP-Link Omada OC200 via REST API with Python
A practical guide to logging into an OC200 controller through REST API v2 with Python — handling CSRF tokens, self-signed certs, fetching sites/devices/SSIDs/DHCP/port-forward rules, and writing back with PATCH, including the read-only fields that cause a nonzero errorCode
Network-as-code on MikroTik RouterOS
A network-as-code approach for MikroTik — save /export output as a file, strip secrets with a sanitize script before sharing, split it into sections, then generate configs for multiple sites from Jinja2 templates + one set of variables
USB in WSL2 with usbipd-win — Real Hardware for Linux on Windows
WSL2 cannot see USB devices because it is a VM without a USB controller — usbipd-win passes devices from Windows directly to the WSL kernel with 3 commands, list/bind/attach, plus lessons from actual use: attachments drop when unplugged, the CRLF trap, and USB modems taking over the default route
LAN Access for a Team of 7 Without Open Ports: Cloudflare Zero Trust
A team of 7 needs RDP access to machines on the LAN without opening any ports to the internet — the Cloudflare Zero Trust architecture (WARP + cloudflared), with 3 lessons from implementation: a forgotten IdP setup, Gateway defaults that allow everything, and the default-deny rule people forget most often
Put an Idle VPS to Work with WireGuard — A Complete Client Guide
Turn a VPS you signed up for on an annual plan into a WireGuard hub for accessing your home LAN anytime, without port forwarding — covering app installation, config imports, QR scanning, troubleshooting, and administration
DA CentOS 7 → Debian 12 on Proxmox Part 1 — NAT pre-stage
Preparing a new VM on an internal bridge with NAT while the old VM continues serving customers, reducing downtime when migrating DirectAdmin from CentOS 7 to Debian 12 on Proxmox.