Why are there so many incoming connections?

Question

linux

Looked at a broad gull and is a little puzzled. Lots of rows from blocked connections. For example:
Mar 18 10:41:03 Home kernel: [ 697.350008] [UFW BLOCK] IN=eth0 OUT= MAC=xxxxxxxxxxxxxxxxxxxxxxxxxx SRC=204.42.253.2 DST=xxxxxxxxxxxx LEN=40 TOS=0x00 PREC=0x00 TTL=53 ID= 11490 DF PROTO=UDP SPT=51374 DPT=123 LEN=20
Mar 18 10:41:55 AM TOS=0x00 PREC=0x00 TTL=49 ID=55103 DF PROTO=UDP SPT=43481 DPT=53413 LEN=9
Mar 18 10:42:03 Home kernel: [ 757.751833] [UFW BLOCK] IN=eth0 OUT= MAC=xxxxxxxxxxxxxxxxxxxxxxxxx SRC=65.52.229.71 DST=xxxxxxxxxxxx LEN=40 TOS=0x00 PREC=0x00 TTL=242 ID=41952 PROTO=TCP SPT=1185 DPT=3389 WINDOW=1024 RES=0x00 SYN URGP=0
The firewall policy blocks all incoming ones, but why are there so many of them? What attracts them? Panic or ignore? Thank you.

Answer 1

DPT=3389, DPT=123, ..., standard potentially vulnerable services. For certain also on sssh passwords will sort out if will find.
Botnets will scan everything they can for vulnerabilities.
Attracts a live host on a white IP address. Humble yourself.
And update.