Internet Relay Chat Flood

Internet Relay Chat Flood

Flooding or scrolling on an IRC network is a method of disconnecting users from an IRC server (a form of Denial of Service), exhausting bandwidth which causes network latency ('lag'), or just annoying users. Floods can either be done by scripts (written for a given client) or by external programs.

It is possible to flood a client off the network simply by sending them data faster than they can receive it and thus cause a quit with the "max sendq exceeded" message, but this is generally only feasible if the user's connection is already slow/lagging and/or the attacker has a very large number of connections to the IRC network. Therefore, more common flooding techniques are based on the fact that the maximum number of messages that can be sent in a specified interval is controlled on the IRC server. Once this value is exceeded messages are stored in a buffer and delayed. If the buffer is filled the client is disconnected with an "Excess Flood" quit message. By sending messages that request an automated reply some IRC clients can be forced to flood themselves off.