Type: yes or no
Default: no

Description: Enables source address spoofing. This means that the host running syslog-ng generates UDP packets with the source IP address matching the original sender of the message. It is useful when you want to perform some kind of preprocessing using syslog-ng then forward messages to your central log management solution with the source address of the original sender. This option only works for UDP destinations though the original message can be received by TCP as well. This option is only available if syslog-ng was compiled using the --enable-spoof-source configuration option.

The maximum size of spoofed datagrams in udp() destinations is set to 1024 bytes by default. To change the maximum size, use the spoof-source-max-msglen() option.

NOTE: Anything above the size of the maximum transmission unit (MTU), which is 1500 bytes by default, is not recommended because of fragmentation.

The maximum datagram in IP protocols (both IPv4 and IPv6) is 65535 bytes including the IP and UDP headers. The minimum size of the IPv4 header is 20 bytes, the IPv6 is 40 bytes, and the UDP is 8 bytes.