<4>Jun 19 20:06:20 hq-ie001 kernel: [258259.060031] [UFW BLOCK] IN=ens5 OUT= MAC=02:89:99:e9:b6:8c:02:63:2d:7a:e2:2d:08:00 SRC=18.51.107.23 DST=171.52.75.226 LEN=26899 TOS=0x00 PREC=0x00 TTL=64 ID=6695 DF PROTO=TCP SPT=9042 DPT=56396 WINDOW=4916 RES=0x00 ACK PSH URGP=0 
This is a syslog message from a product called Uncomplicated Firewall (UFW) by linux. The following fields were extracted from the message:
action: block
clientbytes: 26899
clientport: 56396
facilitylabel: kernel
localhostname: hq-ie001
localstarttime: Jun 19 20:06:20
messagetype: firewall_action
priority: 4
program: kernel
protocol: 6
senderhost: 10.1.100.159
sensitivity: normal
serverport: 9042
severitycode: 4
severitylabel: warning
sourceinfo: unknown
tags: ['rfc3164', 'ufw', 'firewall_action']
streamName: ufw
clientIP: 171.52.75.226
serverIP: 18.51.107.23