HackPacketCheck.txt

Per-opcode packet rate limiting and encryption requirements

Per-opcode anti-cheat packet rules. For each incoming packet, the server looks up the row keyed by opcode (and optional subcode), validates the encryption flag, then applies a two-threshold rate limiter: log-and-reject at MinCount, disconnect at MaxCount.

File Location

Data/Hack/HackPacketCheck.txt

Loaded once at GameServer startup. Changes require a restart.

The Data/Hack/ folder also ships Dec1.dat and Enc2.dat binary encryption blobs. Those are part of the packet encryption scheme used by the Encrypt=1 check here; do not edit them.

Format

Plain text, whitespace-delimited, one packet rule per row. Comment lines start with //. File ends with end.

//Index   Value   Encrypt   MaxDelay   MinCount   MaxCount   //Comment
0         *       0         2000       3          5          //Chat message - anti spam
19        *       0         150        25         40         //Skill attack

Columns

Column	Type	Effect
Index	int 0-255	Packet opcode (also used for extended opcode headers like 0xF1, 0xF3, etc.)
Value	int or *	Subcode filter. * = applies to all subcodes, number = match that subcode only. You may define a wildcard row plus specific subcode rows for the same opcode; the specific row wins for matching subcodes
Encrypt	0, 1, or *	0 = packet must arrive unencrypted, 1 = packet must arrive with valid encryption, * = no encryption check
MaxDelay	int ms	Rate-limiting window length. 0 disables the rate limiter for this row
MinCount	int	Log-and-reject threshold. The MinCount+1-th packet in the window is dropped and logged. 0 disables this check
MaxCount	int	Disconnect threshold. The MaxCount+1-th packet in the window drops the connection. 0 disables this check

Encrypt=0 is not the same as "no encryption check". A row with Encrypt=0 rejects any packet that arrives encrypted. For no check at all, use Encrypt=*.

Rate-Limit Math

For each packet arrival:

1. If the opcode has no row in this file, log an "unknown packet" hack entry and disconnect.

2. If Encrypt is 0 or 1 and the packet's actual encryption does not match, log and disconnect.

3. Serial check (always on, independent of this file): if the packet's serial is invalid, log and disconnect.

4. If the current time is past the window (MaxDelay ms since the first packet of the window), reset the counter and timestamp.

5. Increment the counter. If it now exceeds MinCount, log and reject the packet. If it also exceeds MaxCount, additionally disconnect.

6. Otherwise accept the packet.

Example: Index=0, MaxDelay=2000, MinCount=3, MaxCount=5 accepts the first 3 chat packets per 2-second window, drops the 4th and 5th with a hack log entry, and disconnects on the 6th.

Packet Categories

The shipped file groups opcodes by function. Categories are cosmetic comments only; the engine treats every row independently.

Range	Category
0x00-0x0F	Login / character
0x10-0x1E	Movement / action (combat 0x13-0x1A has the tightest limits)
0x1F-0x2F	Item / inventory
0x30-0x3F	NPC / shop
0x40-0x4F	Party / guild
0x50-0x5F	Trade
0x80-0x8F	Storage
0xC0-0xCF	Chat
0xEC, 0xF1, 0xF3	Extended / GDS / system handlers

Examples

Anti-spam chat

0         *       0         2000       3          5          //Chat message

Chat allows 3 messages per 2-second window. The 4th and 5th are dropped with a hack log entry. The 6th disconnects.

Combat skill limiter

Encryption-only check

Wildcard plus specific subcode

No-check row

Relationship to Common.dat Hack Settings

Common.dat Hack Settings govern behavioral anti-cheat (attack speed reporting, potion spam tracking, combo timing, serial seeds). This file governs packet-level rate limits and the encryption/plaintext contract.

Movement speed hacking is handled by always-on detectors (not configurable via either file).

Cross-File Dependencies

Value	Related in
Encrypt=1 rows	Use the encryption blobs at Data/Hack/Dec1.dat and Enc2.dat
Hack log lines	Gated by Common.dat WriteHackLog
Behavioral anti-cheat	Common.dat Hack Settings
Chat spam filters	Filter.txt complements the opcode-0 rate limiter by blocking disallowed words

Common Issues

• Legit players randomly disconnected during combat - MaxCount too low on opcode 19 (skill attack) or 20 (normal attack); raise in small increments.

• All packets for an opcode rejected after adding a row - row uses Encrypt=0 while the client sends that opcode encrypted, or vice versa. Set Encrypt=* to disable the check.

• Opcode disconnects immediately with "unknown" in hack log - opcode has no row at all. Every handled opcode must have at least one entry (wildcard row is fine).

• Chat spam not blocked - opcode 0 row has MaxDelay=0 or both count thresholds too high. Combine with Filter.txt for word-level filtering.

• Encrypt=1 packets always rejected - encryption blobs missing or corrupt in Data/Hack/, or the client build does not encrypt this opcode.

• Warnings flood the log with no useful signal - MinCount set too low; raise it to reduce noise while keeping MaxCount at the disconnect threshold.

• File edits ignored - a row has fewer than 6 columns; the parser aborts on the malformed row (error popup at startup). Check the server console for the script error line number.

• Different players hit limits at different times - rate window is per-player, measured from their own most recent window reset. There are no shared/global limits in this file.