Minecraft servers occasionally have players who use x-ray mods to find ores such as diamond and emerald by making many blocks in the world transparent. X-ray users can undermine the in-game economy and are easily identified by their mining style and inventories. Fortunately, there are a few Bukkit server plugins that server administrators can install to manage x-ray users, including the Orebfuscator and Anti X-Ray plugins.
Orebfuscator provides ore obfuscation by transforming every block for x-ray users into a clustered display of ores. This is the most effective way to stop x-ray users in their tracks, but unfortunately, ore obfuscation uses a lot of CPU cycles as it needs to process deep packet inspections, do block manipulations, and store those results in memory.
An alternative to ore obfuscation is the Anti X-Ray plugin. Although it is not as effective as ore obfuscation due to the fact that it does not manipulate blocks, it can help deter x-ray users extremely well by giving players a limit on how much they mine, which increases the longer they play on the server.
If players mine too much within the Anti X-Ray limit, they will get a message telling them to wait a certain amount of time. Installing the Anti X-Ray plugin on an established server will not cause a problem for long time players as they will start with their limits set higher than new players.
Finally, server administrators can decrease the value of precious ores, but at the cost of changing the in-game economy set up. Orebfuscator and Anti-Xray are two plugins that will help server administrators manage players who use x-ray mods with ease.