Observed on multiple hosts.

2020-05-04T21:10:09.266800mail.thespaminator.com sshd[26605]: Invalid user isaac from 95.255.14.141 port 51054
2020-05-04T21:10:11.652562mail.thespaminator.com sshd[26605]: Failed password for invalid user isaac from 95.255.14.141 port 51054 ssh2
...

firewall-block, port(s): 5789/tcp

[2020-05-04 23:36:57] NOTICE[1157] chan_sip.c: Registration from '' failed for '185.147.215.14:63369' - Wrong password
[2020-05-04 23:36:57] SECURITY[1173] res_security_log.c: SecurityEvent="InvalidPassword",EventTV="2020-05-04T23:36:57.204-0400",Severity="Error",Service="SIP",EventVersion="2",AccountID="63",SessionID="0x7f5f100266a8",LocalAddress="IPV4/UDP/192.168.244.6/5060",RemoteAddress="IPV4/UDP/185.147.215.14/63369",Challenge="012dbbe3",ReceivedChallenge="012dbbe3",ReceivedHash="b4344640c32ba71a362a10aaf79fd8da"
[2020-05-04 23:37:10] NOTICE[1157] chan_sip.c: Registration from '' failed for '185.147.215.14:56328' - Wrong password
[2020-05-04 23:37:10] SECURITY[1173] res_security_log.c: SecurityEvent="InvalidPassword",EventTV="2020-05-04T23:37:10.080-0400",Severity="Error",Service="SIP",EventVersion="2",AccountID="63",SessionID="0x7f5f1001be58",LocalAddress="IPV4/UDP/192.168.244.6/5060",RemoteAddress="IPV4/UDP/185.147.215.14/563
...

May  5 05:33:46 buvik sshd[31381]: pam_unix(sshd:auth): authentication failure; logname= uid=0 euid=0 tty=ssh ruser= rhost=14.200.247.7
May  5 05:33:48 buvik sshd[31381]: Failed password for invalid user sale from 14.200.247.7 port 40330 ssh2
May  5 05:38:25 buvik sshd[32086]: Invalid user test from 14.200.247.7
...

May  5 05:20:15 mail.srvfarm.net postfix/smtpd[3664405]: warning: unknown[185.50.149.12]: SASL LOGIN authentication failed: UGFzc3dvcmQ6
May  5 05:20:16 mail.srvfarm.net postfix/smtpd[3649783]: lost connection after CONNECT from unknown[185.50.149.12]
May  5 05:20:16 mail.srvfarm.net postfix/smtpd[3664405]: lost connection after AUTH from unknown[185.50.149.12]
May  5 05:20:16 mail.srvfarm.net postfix/smtpd[3665893]: warning: unknown[185.50.149.12]: SASL LOGIN authentication failed: UGFzc3dvcmQ6
May  5 05:20:17 mail.srvfarm.net postfix/smtpd[3665893]: lost connection after AUTH from unknown[185.50.149.12]

[Tue May 05 09:50:34.879537 2020] [:error] [pid 24969:tid 140238167410432] [client 80.82.78.104:54470] [client 80.82.78.104] ModSecurity: Access denied with code 403 (phase 2). Pattern match "^[\\\\d.:]+$" at REQUEST_HEADERS:Host. [file "/etc/modsecurity/owasp-modsecurity-crs-3.2.0/rules/REQUEST-920-PROTOCOL-ENFORCEMENT.conf"] [line "696"] [id "920350"] [msg "Host header is a numeric IP address"] [data "103.27.207.197:80"] [severity "WARNING"] [ver "OWASP_CRS/3.2.0"] [tag "application-multi"] [tag "language-multi"] [tag "platform-multi"] [tag "attack-protocol"] [tag "OWASP_CRS"] [tag "OWASP_CRS/PROTOCOL_VIOLATION/IP_HOST"] [tag "WASCTC/WASC-21"] [tag "OWASP_TOP_10/A7"] [tag "PCI/6.5.10"] [hostname "103.27.207.197"] [uri "/goform/webLogin"] [unique_id "XrDUeiviXZsCcj-lG4KVOAAAAks"], referer: http://103.27.207.197:80/login_inter.asp
...

May  5 03:09:50 server dovecot: imap-login: Aborted login (auth failed, 1 attempts in 2 secs): user=, method=PLAIN, rip=2a02:a03f:3e3b:d900:f1e4:c0fc:50a:cf9, lip=2a01:7e01:e001:164::, session=
May  5 03:09:57 server dovecot: imap-login: Aborted login (auth failed, 1 attempts in 7 secs): user=, method=PLAIN, rip=2a02:a03f:3e3b:d900:f1e4:c0fc:50a:cf9, lip=2a01:7e01:e001:164::, session=
May  5 03:09:57 server dovecot: imap-login: Aborted login (auth failed, 1 attempts in 7 secs): user=, method=PLAIN, rip=2a02:a03f:3e3b:d900:f1e4:c0fc:50a:cf9, lip=2a01:7e01:e001:164::, session=
May  5 03:10:05 server dovecot: imap-login: Aborted login (auth failed, 1 attempts in 2 secs): user=, method=PLAIN, rip=2a02:a03f:3e3b:d900:f1e4:c0fc:50a:cf9, lip=2a01:7e01:e001:164::, session=

...

May  5 04:44:50 tuxlinux sshd[33110]: pam_unix(sshd:auth): authentication failure; logname= uid=0 euid=0 tty=ssh ruser= rhost=106.12.168.83  user=root
May  5 04:44:52 tuxlinux sshd[33110]: Failed password for root from 106.12.168.83 port 56806 ssh2
May  5 04:44:50 tuxlinux sshd[33110]: pam_unix(sshd:auth): authentication failure; logname= uid=0 euid=0 tty=ssh ruser= rhost=106.12.168.83  user=root
May  5 04:44:52 tuxlinux sshd[33110]: Failed password for root from 106.12.168.83 port 56806 ssh2
May  5 04:59:27 tuxlinux sshd[33448]: Invalid user paulo from 106.12.168.83 port 43340
...

2020-05-05T01:09:16.791892shield sshd\[10858\]: pam_unix\(sshd:auth\): authentication failure\; logname= uid=0 euid=0 tty=ssh ruser= rhost=62.82.75.58.static.user.ono.com  user=root
2020-05-05T01:09:18.221940shield sshd\[10858\]: Failed password for root from 62.82.75.58 port 16613 ssh2
2020-05-05T01:10:04.942304shield sshd\[11176\]: Invalid user deep from 62.82.75.58 port 10410
2020-05-05T01:10:04.946229shield sshd\[11176\]: pam_unix\(sshd:auth\): authentication failure\; logname= uid=0 euid=0 tty=ssh ruser= rhost=62.82.75.58.static.user.ono.com
2020-05-05T01:10:06.631101shield sshd\[11176\]: Failed password for invalid user deep from 62.82.75.58 port 10410 ssh2

Port probing on unauthorized port 5432

05/05/2020-03:10:18.722454 162.243.143.62 Protocol: 6 ET SCAN Suspicious inbound to PostgreSQL port 5432

May  5 05:38:54 eventyay sshd[17509]: Failed password for proxy from 5.135.158.228 port 51552 ssh2
May  5 05:45:23 eventyay sshd[17703]: pam_unix(sshd:auth): authentication failure; logname= uid=0 euid=0 tty=ssh ruser= rhost=5.135.158.228
May  5 05:45:26 eventyay sshd[17703]: Failed password for invalid user caja01 from 5.135.158.228 port 35182 ssh2
...

Honeypot attack, port: 5555, PTR: PTR record not found