ConfigServer Security & Firewall
CSF Login Failure Daemon (LFD) blocks
It's possible you or your customers get blocked by the security mechanisms of the ConfigServer Firewall. The LFD component could block too many failed login attempts to SSH, FTP, POP3, IMAP, HTTP, etc.
Unlike other applications, LFD is a daemon process that monitors logs continuously and so can react within seconds of detecting such attempts. It also monitors across protocols, so if attempts are made on different protocols in a short space of time, all those attempts will be counted against the threshold.
It's possible to ignore some IP-Addresses for your office, home office or third party that are working for something like testing the website/application or if you running a vulnerability scan. Sometimes it can be happy that you will be blocked by the CSF for many failed logins how we explained here above the article. Ignoring an IP-address will be a good solutions to avoid blocking.
Ignoring (Whitelisting) an IP Address
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To ignore an IP address in the firewall (csf.ignore), you can enter the IP address into the Quick Ignore section, allow such as “Office network”, and click the Quick Ignore button.