This plugin limits the amount of players that can join the server from the same (lobby) group
When a player joins, the plugin will notify the player how many group members are online and what the maximum allowed amount is. When the player is the group member thats over the limit, he will get kicked.
The plugin does not kick players with the group.bypass permission. Additionally you can whitelist specific Steam groups in the configuration file. You need the Steam group’s id for this and its name (can be anything you want actually, just to make it easier). You can also do this with the command /gwhitelist if the player is on the server.
The id can be found by getting the group’s link e.g. http://steamcommunity.com/groups/rocketmod and adding /memberslistxml/?xml=1 to it.
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