Estou usando o CentOS v7 e tentei definir MaxAuthTries 6 , embora isso não pareça funcionar. Estou usando o PAM para que a propriedade UsePAM yes seja definida. Eu não tenho certeza se é um bug ou algo mais que bloqueia a autenticação tenta mais de 3.
Nos registros, estou obtendo os resultados abaixo
[root@webserver ~]# sshd -T | grep -i 'pam\|authtries\|gracetime'
usepam yes
logingracetime 600
maxauthtries 6
[root@webserver ~]# tail -f /var/log/secure
Mar 26 12:04:41 webserver systemd: Stopping OpenSSH server daemon...
Mar 26 12:04:41 webserver systemd: Starting OpenSSH server daemon...
Mar 26 12:04:41 webserver systemd: PID file /var/run/sshd.pid not readable (yet?) after start.
Mar 26 12:04:41 webserver sshd[2308]: Server listening on 0.0.0.0 port 22.
Mar 26 12:04:41 webserver sshd[2308]: Server listening on 0.0.0.0 port 22.
Mar 26 12:04:41 webserver sshd[2308]: Server listening on :: port 22.
Mar 26 12:04:41 webserver sshd[2308]: Server listening on :: port 22.
Mar 26 12:04:41 webserver polkitd[687]: Unregistered Authentication Agent for unix-process:2301:105272 (system bus name :1.23, object path /org/freedesktop/PolicyKit1/AuthenticationAgent, locale en_US.UTF-8) (disconnected from bus)
Mar 26 12:04:41 webserver polkitd[687]: Unregistered Authentication Agent for unix-process:2301:105272 (system bus name :1.23, object path /org/freedesktop/PolicyKit1/AuthenticationAgent, locale en_US.UTF-8) (disconnected from bus)
Mar 26 12:04:41 webserver systemd: Started OpenSSH server daemon.
Mar 26 12:05:16 webserver unix_chkpwd[2318]: password check failed for user (test)
Mar 26 12:05:16 webserver unix_chkpwd[2318]: password check failed for user (test)
Mar 26 12:05:16 webserver sshd[2316]: pam_unix(sshd:auth): authentication failure; logname= uid=0 euid=0 tty=ssh ruser= rhost=gateway user=test
Mar 26 12:05:16 webserver sshd[2316]: pam_unix(sshd:auth): authentication failure; logname= uid=0 euid=0 tty=ssh ruser= rhost=gateway user=test
Mar 26 12:05:18 webserver sshd[2316]: Failed password for test from 192.168.124.1 port 48936 ssh2
Mar 26 12:05:18 webserver sshd[2316]: Failed password for test from 192.168.124.1 port 48936 ssh2
Mar 26 12:05:20 webserver unix_chkpwd[2319]: password check failed for user (test)
Mar 26 12:05:20 webserver unix_chkpwd[2319]: password check failed for user (test)
Mar 26 12:05:22 webserver sshd[2316]: Failed password for test from 192.168.124.1 port 48936 ssh2
Mar 26 12:05:22 webserver sshd[2316]: Failed password for test from 192.168.124.1 port 48936 ssh2
Mar 26 12:05:25 webserver unix_chkpwd[2320]: password check failed for user (test)
Mar 26 12:05:25 webserver unix_chkpwd[2320]: password check failed for user (test)
Mar 26 12:05:27 webserver sshd[2316]: Failed password for test from 192.168.124.1 port 48936 ssh2
Mar 26 12:05:27 webserver sshd[2316]: Failed password for test from 192.168.124.1 port 48936 ssh2
Mar 26 12:05:27 webserver sshd[2316]: Connection closed by 192.168.124.1 [preauth]
Mar 26 12:05:27 webserver sshd[2316]: Connection closed by 192.168.124.1 [preauth]
Mar 26 12:05:27 webserver sshd[2316]: PAM 2 more authentication failures; logname= uid=0 euid=0 tty=ssh ruser= rhost=gateway user=test
Mar 26 12:05:27 webserver sshd[2316]: PAM 2 more authentication failures; logname= uid=0 euid=0 tty=ssh ruser= rhost=gateway user=test
Existe uma opção no lado do cliente ( ssh_config ), NumberOfPasswordPrompts , que por padrão está definida como 3. Por isso, não pude ir além de 3 tentativas.
NumberOfPasswordPrompts
Specifies the number of password prompts before giving up. The argument to this keyword must be an integer. The default is 3.