This module accepts UDP datagrams on the configured address and port. UDP is the transport protocol of the legacy BSD Syslog as described in RFC 3164, so this module can be particularly useful to receive such messages from older devices that do not support other transports.
|To examine the supported platforms, see the list of installer packages in the Available Modules chapter.|
|UDP is an unreliable transport protocol and does not guarantee delivery. Messages may not be received or may be truncated. It is recommended to use the TCP or SSL transport modules instead, if possible.|
To reduce the likelihood of message loss, consider:
|This module does not provide access control. Firewall rules can be used to deny connections from certain hosts.|
For parsing syslog messages, see the parse_syslog_bsd() procedure of the xm_syslog module.
The im_udp module accepts the following directives in addition to the common module directives.
The module accepts connections on the IP address or hostname and port defined here. The default address is
localhostand the default port is 514. The port number can be defined by appending it at the end of the hostname or IP address using a colon as a separator (
host:port). The port section of this directive and the Port directive are mutually exclusive. In case both are defined, the port number defined here takes precedence over a port defined in the Port directive. In case none of them is defined, the default port 514 is used.
To listen on multiple addresses or ports in a single module instance, this directive can be repeated multiple times. Both IPv4 and IPv6 addresses are supported. If a DNS name is used, the number of addresses or cnames should be kept below 16 to avoid potential issues caused by DNS response size limits.
|Formerly called Host, this directive is now ListenAddr. Host will become deprecated from NXLog EE 6.0.|
For client applications that don’t support IPv6, to avoid the behavior
described above the
Alternatively, the server-side system may be configured to prioritize IPv4
addresses for the hostname specified by the
For more information see the Microsoft documentation on Configuring IPv6 in Windows for advanced users.
This limitation will be addressed in a future release by making listening modules bind to all available IPv4/IPv6 addresses that a hostname resolves to.
The module will listen for incoming connections on this port number. The default is port 514.
|The Port directive will become deprecated from NXLog EE 6.0. After that, the port can only be defined in the ListenAddr directive.|
This optional boolean directive enables synchronous listening on the same port by multiple module instances. Each module instance runs in its own thread, allowing NXLog to process incoming data simultaneously to take better advantage of multiprocessor systems. The default value is FALSE.
To enable synchronous listening, the configuration file should contain multiple im_udp module instances listening on the same port and the ReusePort directive set to TRUE, see the Examples section.
This optional directive sets the socket buffer size (SO_RCVBUF) to the value specified. If not set, the operating system defaults are used. If UDP packet loss is occurring at the kernel level, setting this to a high value (such as
150000000) may help. On Windows systems, the default socket buffer size is extremely low, and using this option is highly recommended.
This boolean directive specifies that the
recvmmsg()system call should be used, if available, to receive multiple messages per call to improve performance. The default is TRUE.
Pre-v5 syntax examples are included, they will become invalid with NXLog EE 6.0.
This configuration accepts log messages via UDP and writes them to a file.
<Input udp> Module im_udp ListenAddr 192.168.1.1:514 </Input> # Using the syntax prior to NXLog EE 5, # where the port is defined in a separate directive. #<Input udp> # Module im_udp # Host 192.168.1.1 # Port 514 #</Input> <Output file> Module om_file File "tmp/output" </Output> <Route udp_to_file> Path udp => file </Route>
The configuration below provides two im_udp module instances to reuse port 514 via the ReusePort directive.
Received messages are written to the
<Input udp_one> Module im_udp ListenAddr 192.168.1.1:514 ReusePort TRUE </Input> <Input udp_two> Module im_udp ListenAddr 192.168.1.1:514 ReusePort TRUE </Input> # Using the syntax prior to NXLog EE 5, # where the port is defined in a separate directive. #<Input udp_one> # Module im_udp # Host 192.168.1.1 # Port 514 # ReusePort TRUE #</Input> # #<Input udp_two> # Module im_udp # Host 192.168.1.1 # Port 514 # ReusePort TRUE #</Input> <Output file> Module om_file File "tmp/output" </Output> <Route udp_to_file> Path udp_one, udp_two => file </Route>