Listens for Syslog messages being sent to a given port over TCP or UDP. Incoming messages are checked against regular expressions for RFC5424 and RFC3164 formatted messages. The format of each message is: (<PRIORITY>)(VERSION )(TIMESTAMP) (HOSTNAME) (BODY) where version is optional. The timestamp can be an RFC5424 timestamp with a format of “yyyy-MM-dd’T’HH:mm:ss.SZ” or “yyyy-MM-dd’T’HH:mm:ss.S+hh:mm”, or it can be an RFC3164 timestamp with a format of “MMM d HH:mm:ss”. If an incoming messages matches one of these patterns, the message will be parsed and the individual pieces will be placed in FlowFile attributes, with the original message in the content of the FlowFile. If an incoming message does not match one of these patterns it will not be parsed and the syslog.valid attribute will be set to false with the original message in the content of the FlowFile. Valid messages will be transferred on the success relationship, and invalid messages will be transferred on the invalid relationship.


syslog, listen, udp, tcp, logs


In the list below, the names of required properties appear in bold. Any other properties (not in bold) are considered optional. The table also indicates any default values, and whether a property supports the Expression Language Guide.

Name Default Value Allowable Values Description
Protocol UDP * TCP</br> * UDP The protocol for Syslog communication.
Port The port for Syslog communication.
Local Network Interface The name of a local network interface to be used to restrict listening to a specific LAN.
Supports Expression Language: true
SSL Context Service Controller Service API:
The Controller Service to use in order to obtain an SSL Context. If this property is set, syslog messages will be received over a secure connection.
Receive Buffer Size 65507 B The size of each buffer used to receive Syslog messages. Adjust this value appropriately based on the expected size of the incoming Syslog messages. When UDP is selected each buffer will hold one Syslog message. When TCP is selected messages are read from an incoming connection until the buffer is full, or the connection is closed.
Max Size of Message Queue 10000 The maximum size of the internal queue used to buffer messages being transferred from the underlying channel to the processor. Setting this value higher allows more messages to be buffered in memory during surges of incoming messages, but increases the total memory used by the processor.
Max Size of Socket Buffer 1 MB The maximum size of the socket buffer that should be used. This is a suggestion to the Operating System to indicate how big the socket buffer should be. If this value is set too low, the buffer may fill up before the data can be read, and incoming data will be dropped.
Max Number of TCP Connections 2 The maximum number of concurrent connections to accept Syslog messages in TCP mode.
Max Batch Size 1 The maximum number of Syslog events to add to a single FlowFile. If multiple events are available, they will be concatenated along with the <Message Delimiter> up to this configured maximum number of messages
Message Delimiter \n Specifies the delimiter to place between Syslog messages when multiple messages are bundled together (see <Max Batch Size> property).
Parse Messages true * true * false Indicates if the processor should parse the Syslog messages. If set to false, each outgoing FlowFile will only contain the sender, protocol, and port, and no additional attributes.
Character Set UTF-8 Specifies the character set of the Syslog messages


Name Description
invalid Syslog messages that do not match one of the expected formats will be sent out this relationship as a FlowFile per message.
success Syslog messages that match one of the expected formats will be sent out this relationship as a FlowFile per message.

Reads Attributes:

None specified.

Writes Attributes:

Name Description
syslog.priority The priority of the Syslog message.
syslog.severity The severity of the Syslog message derived from the priority.
syslog.facility The facility of the Syslog message derived from the priority.
syslog.version The optional version from the Syslog message.
syslog.timestamp The timestamp of the Syslog message.
syslog.hostname The hostname of the Syslog message.
syslog.sender The hostname of the Syslog server that sent the message.
syslog.body The body of the Syslog message, everything after the hostname.
syslog.valid An indicator of whether this message matched the expected formats. If this value is false, the other attributes will be empty and only the original message will be available in the content.
syslog.protocol The protocol over which the Syslog message was received.
syslog.port The port over which the Syslog message was received.
mime.type The mime.type of the FlowFile which will be text/plain for Syslog messages.

See Also: