Malformed Messages and Message Properties
A common trouble source are ill-formed syslog messages, which lead to to all sorts of interesting problems, including malformed hostnames and dates. -Read the quoted guide to find relief. +Read the quoted guide to find relief. A common symptom is that the %HOSTNAME% property is +used for generating dynafile names, but some glibberish shows up. This is caused by the +malformed syslog messages, so be sure to read the +guide if you face that problem. Just let me add that the +common work-around is to use %FROMHOST% or %FROMHOST-IP% instead. These do not take the +hostname from the message, but rather use the host that sent the message (taken from +the socket layer). Of course, this does not work over NAT or relay chains, where the +only cure is to make sure senders emit well-formed messages.
Configuration Problems
Rsyslog 3.21.1 and above has been enhanced to support extended configuration checking. It offers a special command line switch (-N1) that puts it into "config verfication mode".