Dec  6 22:27:23 relay postfix/smtpd\[29308\]: NOQUEUE: reject: RCPT from unknown\[181.41.216.140\]: 554 5.7.1 \: Relay access denied\; from=\ to=\ proto=ESMTP helo=\<\[181.41.216.131\]\>
Dec  6 22:27:23 relay postfix/smtpd\[29308\]: NOQUEUE: reject: RCPT from unknown\[181.41.216.140\]: 554 5.7.1 \: Relay access denied\; from=\ to=\ proto=ESMTP helo=\<\[181.41.216.131\]\>
Dec  6 22:27:23 relay postfix/smtpd\[29308\]: NOQUEUE: reject: RCPT from unknown\[181.41.216.140\]: 554 5.7.1 \: Relay access denied\; from=\ to=\ proto=ESMTP helo=\<\[181.41.216.131\]\>
Dec  6 22:27:23 relay postfix/smtpd\[29308\]: NOQUEUE: reject: RCPT from unknown\[181.41.216.140\]: 554 5.7.1 \: Relay access denied\; from=\ to=\

2019-12-06T15:09:59.628806-07:00 suse-nuc sshd[14531]: Invalid user netm from 217.199.28.173 port 56120
...

Attempted to connect 2 times to port 23 TCP

Dec  6 10:48:23 auw2 sshd\[25884\]: Invalid user albertm from 45.80.65.80
Dec  6 10:48:23 auw2 sshd\[25884\]: pam_unix\(sshd:auth\): authentication failure\; logname= uid=0 euid=0 tty=ssh ruser= rhost=45.80.65.80
Dec  6 10:48:25 auw2 sshd\[25884\]: Failed password for invalid user albertm from 45.80.65.80 port 42770 ssh2
Dec  6 10:54:56 auw2 sshd\[26533\]: Invalid user roziers from 45.80.65.80
Dec  6 10:54:56 auw2 sshd\[26533\]: pam_unix\(sshd:auth\): authentication failure\; logname= uid=0 euid=0 tty=ssh ruser= rhost=45.80.65.80

Dec  6 15:23:25 pl1server sshd[16872]: Invalid user user from 223.182.30.155
Dec  6 15:23:25 pl1server sshd[16872]: pam_unix(sshd:auth): authentication failure; logname= uid=0 euid=0 tty=ssh ruser= rhost=223.182.30.155
Dec  6 15:23:27 pl1server sshd[16872]: Failed password for invalid user user from 223.182.30.155 port 11094 ssh2
Dec  6 15:23:27 pl1server sshd[16872]: Connection closed by 223.182.30.155 [preauth]


........
-----------------------------------------------
https://www.blocklist.de/en/view.html?ip=223.182.30.155

2019-12-06 20:35:50,861 fail2ban.actions        \[14488\]: NOTICE  \[sshd\] Ban 80.211.179.154
2019-12-06 21:10:56,072 fail2ban.actions        \[14488\]: NOTICE  \[sshd\] Ban 80.211.179.154
2019-12-06 21:51:21,902 fail2ban.actions        \[14488\]: NOTICE  \[sshd\] Ban 80.211.179.154
2019-12-06 22:25:56,998 fail2ban.actions        \[14488\]: NOTICE  \[sshd\] Ban 80.211.179.154
2019-12-06 23:00:39,054 fail2ban.actions        \[14488\]: NOTICE  \[sshd\] Ban 80.211.179.154
...

Dec  6 22:34:58 minden010 sshd[20034]: pam_unix(sshd:auth): authentication failure; logname= uid=0 euid=0 tty=ssh ruser= rhost=134.175.6.69
Dec  6 22:35:00 minden010 sshd[20034]: Failed password for invalid user hchc from 134.175.6.69 port 54758 ssh2
Dec  6 22:41:13 minden010 sshd[22184]: pam_unix(sshd:auth): authentication failure; logname= uid=0 euid=0 tty=ssh ruser= rhost=134.175.6.69
...

Dec  6 15:22:57 saengerschafter sshd[11132]: pam_unix(sshd:auth): authentication failure; logname= uid=0 euid=0 tty=ssh ruser= rhost=79-73-63-65.dynamic.dsl.as9105.com  user=r.r
Dec  6 15:23:00 saengerschafter sshd[11132]: Failed password for r.r from 79.73.63.65 port 34411 ssh2
Dec  6 15:23:04 saengerschafter sshd[11132]: message repeated 2 serveres: [ Failed password for r.r from 79.73.63.65 port 34411 ssh2]
Dec  6 15:23:05 saengerschafter sshd[11132]: Failed password for r.r from 79.73.63.65 port 34411 ssh2
Dec  6 15:23:09 saengerschafter sshd[11132]: message repeated 2 serveres: [ Failed password for r.r from 79.73.63.65 port 34411 ssh2]
Dec  6 15:23:09 saengerschafter sshd[11132]: error: maximum authentication attempts exceeded for r.r from 79.73.63.65 port 34411 ssh2 [preauth]
Dec  6 15:23:09 saengerschafter sshd[11132]: PAM 5 more authentication failures; logname= uid=0 euid=0 tty=ssh ruser= rhost=79-73-63-65.dynamic.dsl.as9105.com  user=r.r
Dec  6 15:23:11 saeng........
-------------------------------

detected by Fail2Ban

SSH invalid-user multiple login try

Unauthorised access (Dec  6) SRC=5.227.39.107 LEN=52 TTL=110 ID=31942 DF TCP DPT=445 WINDOW=8192 SYN 
Unauthorised access (Dec  6) SRC=5.227.39.107 LEN=52 TTL=110 ID=18230 DF TCP DPT=445 WINDOW=8192 SYN

Dec  6 17:29:58 mail sshd[8630]: Invalid user hf from 45.131.186.142
Dec  6 17:29:58 mail sshd[8630]: pam_unix(sshd:auth): authentication failure; logname= uid=0 euid=0 tty=ssh ruser= rhost=45.131.186.142
Dec  6 17:30:00 mail sshd[8630]: Failed password for invalid user hf from 45.131.186.142 port 40084 ssh2
Dec  6 17:41:46 mail sshd[8891]: Invalid user kashuba from 45.131.186.142
Dec  6 17:41:46 mail sshd[8891]: pam_unix(sshd:auth): authentication failure; logname= uid=0 euid=0 tty=ssh ruser= rhost=45.131.186.142

........
-----------------------------------------------
https://www.blocklist.de/en/view.html?ip=45.131.186.142

$f2bV_matches

Dec  6 15:44:59 flomail dovecot: imap-login: Disconnected (auth failed, 1 attempts in 6 secs): user=, method=PLAIN, rip=203.147.78.247, lip=10.140.194.78, TLS: Disconnected, session=
Dec  6 15:44:59 flomail dovecot: imap-login: Disconnected (auth failed, 1 attempts in 6 secs): user=, method=PLAIN, rip=203.147.78.247, lip=10.140.194.78, TLS: Disconnected, session=

Dec  6 23:19:03 srv206 sshd[22172]: Invalid user apache from 73.242.200.160
Dec  6 23:19:03 srv206 sshd[22172]: pam_unix(sshd:auth): authentication failure; logname= uid=0 euid=0 tty=ssh ruser= rhost=c-73-242-200-160.hsd1.nm.comcast.net
Dec  6 23:19:03 srv206 sshd[22172]: Invalid user apache from 73.242.200.160
Dec  6 23:19:05 srv206 sshd[22172]: Failed password for invalid user apache from 73.242.200.160 port 46082 ssh2
...