When your server is under attack, "we're being DDoSed" is not actionable; "SYN flood, four million packets per second, spoofed sources, targeting port 443" is. The difference between the two is a thirty-second packet capture and a structured look at it. This guide covers capturing safely on a machine that's already saturated (tcpdump, not the Wireshark GUI), the triage workflow in Wireshark (Protocol Hierarchy, Conversations, I/O Graphs) and the display-filter signatures of the common attack vectors, ending with how to turn findings into mitigation.

DDoS attacks come in three broad families: volumetric floods that saturate your pipe, protocol attacks that exhaust connection state, and application-layer floods that look like legitimate traffic. Each one exhausts a different resource, so each one needs a different defence, and no single layer stops all three. This guide maps the common attack forms to the resource they target and the mitigation that actually works against them, explains what an on-host firewall can and cannot stop, and ends with a practical incident-response runbook for when your server is under fire.

Ping is only part of what a player feels. A single round trip runs through input sampling, the last mile, transit and peering, a queue on the server, and the wait for the next simulation tick before the world reacts at all. This guide breaks down where felt delay actually comes from, how tick rate and netcode change the picture, why jitter and packet loss hurt more than a stable higher ping, and the one lever a host controls most: putting the server close to players on hardware that holds its tick rate.

Netplan is the YAML layer that configures networking on Ubuntu Server: you describe addresses, routes and DNS in one file, and a generator renders that into config for systemd-networkd. This crash course is written for a dedicated box with a static public IP, no Wi-Fi, and SSH as the only way in. It covers where the files live, the root-only 600 permission rule, a full static IPv4 and IPv6 example, the generate, try and apply commands that stop you locking yourself out, plus VLANs, bonds, bridges, and the cloud-init file that keeps overwriting people's edits.

NetworkManager is the daemon that configures the network on every RHEL-family server, and since RHEL dropped the old network-scripts it is the only supported way to do it. This crash course runs it the way a dedicated server uses it: headless, static, over SSH, with nmcli and keyfiles instead of a desktop applet. You will learn the device-and-profile model that clears up most nmcli confusion, a full static IPv4 and IPv6 setup you can paste and adapt, where profiles live on disk across RHEL 8, 9, and 10, and how to change the network on a remote box without locking yourself out.