The title says it all. Check Log4Net site or RabbitMQ site if you need more info.
Get it on NuGet, or download sources and run build.cmd to build
<appender name="RabbitMQAppender" type="log4net.Appender.RabbitMQAppender, Log4Rabbit">
<HostName value="localhost"/> <!-- Default to localhost -->
<VirtualHost value="/"/> <!-- Default to / -->
<UserName value="guest"/> <!-- Default to guest -->
<Password value="guest"/> <!-- Default to guest -->
<RequestedHeartbeat value="0"/> <!-- Value in seconds, default to 0 that mean no heartbeat -->
<Port value="5672"/> <!-- Default to 5672 -->
<Exchange value="logs"/> <!-- Default to logs -->
<RoutingKey value=""/> <!-- Default to empty -->
<FlushInterval value="5"/> <!-- Seconds to wait between message send. Default to 5 seconds -->
</appender>