VeloFlame overview

VeloFlame is a Velocity proxy fork shipped as the proxy JAR itself, not as a Bukkit plugin. It keeps the Velocity plugin and API surface and adds admission controls around it: early packet limits, per-IP rate limits, an expiring firewall, limbo verification and maintenance controls. The runtime brand and configuration are VeloFlame; the inherited README.md heading still says Velocity-CTD, and the code retains upstream com.velocitypowered.* and com.velocityctd.* packages.

Field	Verified value
Runtime version	1.4.9
Upstream identity	Velocity / Velocity-CTD fork
License	GNU GPL v3
JAR names	VeloFlame-Lite.jar, VeloFlame-Pro.jar
Configuration	veloflame.toml next to velocity.toml
Gradle project version	4.2.1-SNAPSHOT; not the runtime release label

Where it sits in the connection path

The controls are ordered from cheapest to most expensive:

1. Frame and compression checks. MinecraftVarintFrameDecoder validates a frame before the packet object exists. MinecraftCompressDecoder checks the claimed and inflated sizes, and ServerboundCompressionGuard rejects serverbound compression ratios above the system property velocity.serverbound-max-compression-ratio (default 1024) or claimed sizes above velocity.serverbound-uncompressed-cap (default 2097152).
2. Per-state early limiter. A sliding window tracks packet count, wire bytes and decompressed bytes separately for HANDSHAKE, STATUS, LOGIN, CONFIG and PLAY. A handshake budget is deliberately much smaller than a play budget.
3. Rate limits. Login and status counters are separate. Reaching a limit can add the address to the firewall once per window.
4. Firewall. Blocked addresses live in a Caffeine cache with a configurable TTL. The optional host path adds them to an ipset set and installs an iptables INPUT drop rule.
5. Limbo. A login can be diverted before PreLoginEvent, verified by a limbo session, and only then transferred to the backend. Admission is queue-bound and event-loop aware; the code rejects off-loop calls rather than touching session state from the wrong thread.

Editions

VeloFlame.isPro() selects the edition shown by /veloflame, and the two builds have different JAR names. The shipped configuration marks six sections as PRO-only: vpn, vpn-online, account, reconnect, nickname and limbo. Do not assume a default-enabled section exists in the Lite artifact. Verify the JAR you actually run before planning around a module.

Requirements

Requirement	Verified detail
Proxy	Velocity-compatible fork; started as the proxy JAR
Java	Build toolchain is Java 25; no runtime minimum is documented
Existing files	velocity.toml and forwarding.secret in the working directory
Generated file	veloflame.toml, created on first start
External plugin	None required to boot the proxy
Host firewall	Linux ipset and iptables plus root or CAP_NET_ADMIN for the optional path
Client range	Not declared in metadata

The Java 25 entry is a build toolchain, not a documented runtime floor. Test the artifact on the JVM you intend to deploy and pin it.

Defaults to review before production

Default	Value	Risk
settings.whitelist	localhost/private addresses plus "LinsaFTW"	Grants that username bypass out of the box
limbo.transfer.destination-host	"play.my-server.com"	Placeholder; post-verification transfer is enabled
firewall.ipset	true	Needs host privileges; falls back to the Java cache
limbo.always-active	false	Limbo triggers on join pressure, not every connection

The shipped limbo transfer block is enabled with use-handshake-hostname = true and port 25565. Change the host or disable the transfer before exposing the proxy.

What is not claimed

• No tested Minecraft client or backend version range is declared.
• This is a proxy; backend support statements in the inherited README are project goals, not a compatibility matrix.
• Lite feature parity with PRO is not established by the shared configuration file.
• The placeholder transfer destination is not a working endpoint.

For the deployment sequence see install VeloFlame. For keys and defaults see configuration. The VeloFlame case study covers the limbo and packet-guard design decisions.

Verified against VeloFlame 019f32053 (runtime version 1.4.9, 4 October 2026) on 30 October 2026. Values come from source and the shipped default-veloflame.toml; no live proxy run was performed.