Tag: linux

Time Sync on VMs: Why NTP Keeps Drifting

Your VM's clock is off by minutes, NTP says it's synced, yet the system keeps drifting. Here's why the hypervisor is the real culprit, and how to fix it.

The MTU Problem Nobody Diagnoses Correctly

MTU mismatches silently break large file transfers, backups, and video calls. Here's how to find and fix the wrong frame size on your network.

VPN Kill Switch and DNS Leak Prevention: Paranoia, Justified

Set up a WireGuard VPN kill switch and prevent DNS leaks on Linux. Practical iptables rules, resolv.conf locking, and systemd-resolved config.

BGP in Your Home Lab: Dynamic Routing for People Who've Run Out of Static Routes

Run BGP in your home lab with FRRouting. Covers iBGP vs eBGP, FRR installation, basic BGP config, peering with OPNsense, route filtering, and when BGP is actually worth the complexity.

DNS Troubleshooting from the Command Line

DNS broke again. Here's the exact command sequence to figure out what's happening without touching a GUI.

Linux Capabilities: Drop Root Without Breaking Everything

Learn Linux capabilities to drop root privileges without breaking your apps. Master cap_drop, cap_add in Docker, and setcap for fine-grained privilege control.

curl Flags Every Developer Should Know

Master the curl flags that'll save you hours debugging APIs, downloads, and web requests. From -X to --compressed, here's what actually matters.

Named Pipes (FIFOs) in Shell Scripts

Named pipes (FIFOs) let you buffer and synchronize between processes. They're underused but solve real problems: queuing, coordination, and complex data flows.

UFW Advanced: Rate Limiting, Logging, and Rules That Actually Make Sense

Go beyond ufw allow/deny: rate limiting with ufw limit, logging levels, before.rules for iptables, IPv6 handling, Docker bypass fixes, and fail2ban integration.

Bash Arrays: The Feature That Makes Scripts Readable

Declare, iterate, slice, and manipulate bash arrays safely. Indexed and associative arrays, the @ vs * trap, and patterns that make scripts readable.

Bash Process Substitution: What <() and >() Actually Do

Process substitution lets you treat a command's output as a file, and feed input to a command as if it were a file. It's weird but powerful.

Here Documents vs Here Strings in Bash

Bash heredocs and here strings explained: <<EOF for multiline input, <<-EOF for tab-indented blocks, <<<string for single lines, and when to use each.