By default, rsyslog does not listen for log messages coming in from remote systems. The ModLoad tells rsyslog to load the imtcp.so module so it can listen over a network via TCP. The InputTCPServerRun option instructs rsyslogd to listen on the specified TCP port. The guidance in the section ensures that remote log hosts are configured to only accept rsyslog data from hosts within the specified domain and that those systems that are not designed to be log hosts do not accept any remote rsyslog messages. This provides protection from spoofed log data and ensures that system administrators are reviewing reasonably complete syslog data in a central location.