Server Logs (Para servidores Linux con CWP)
Si usted administra un servidor con Centos Web Panel, ésta información le ayudará a resolver problemas y hacer análisis oportunos que permitan el correcto funcionamiento del servidor. (FUENTE: https://wiki.centos-webpanel.com/service-log-paths)

Apache logs are in folder
/usr/local/apache/logs (main logs)
/usr/local/apache/domlogs (per domain logs are in the same file for apache&nginx)
Nginx logs are in folder
/var/log/nginx/
/usr/local/apache/domlogs (per domain logs are in the same file for apache&nginx)
Mod Security (per domain logs, replace DOMAIN.COM)
/usr/local/apache/domlogs/DOMAIN.COM.error.log
CWP server logs and server services logs, including (PhpMyAdmin/Roundcube/API):
/usr/local/cwpsrv/logs/
/usr/local/cwp/php71/var/log/
CWP WebServers rebuild log for vhosts including php-fpm conf:
/var/log/cwp/webservers.log
CSF & LFD firewall logs
/var/log/lfd.log
SSH logs
/var/log/secure
Yum logs
/var/log/yum.log
FTP logs
/var/log/messages
Postfix / Mail
/var/log/maillog
Failed SMTP Login example (mail client software: thunderbird, outlook):
Dovecot and Dovecot debug logs
dovecot.log
dovecot-info.log
dovecot-debug.log
Failed IMAP/POP3 Logins
/var/log/dovecot-info.log
Failed Login examle (mail client software: thunderbird, outlook):
Failed Login example roundcube:
imap-login: Info: Disconnected (auth failed, 1 attempts): user=username@domain.net, method=PLAIN, rip=127.0.0.1, lip=127.0.0.1, secured
Success Login roundcube:
Success Login example (mail client software: thunderbird, outlook):
Roundcube (CWP version 160+)
/usr/local/cwpsrv/var/services/roundcube/logs/
example of /usr/local/cwpsrv/var/services/roundcube/logs/sendmail:
Failed Logins
/usr/local/cwpsrv/var/services/roundcube/logs/errors
example /var/log/dovecot-info.log:
MySQL logs
/var/lib/mysql/HOSTNAME.err
Bind/Named logs
/var/log/messages