cPanel IP block – How to resolve and prevent IP blocks in cPanel/WHM servers
Firewalls such as CSF/LFD are usually configured in cPanel servers as a security measure. These firewalls protect the servers by blocking IP addresses of attackers or malicious users.
But we’ve seen cases where these firewall settings are not proper, and even valid users trying to access their websites get blocked. Users then approach server owners, complaining about site unavailability.
At Bobcares, our engineers have resolved numerous such IP block issues, as a part of managing hundreds of cPanel servers in their role as website management specialists for web hosting companies.
cPanel IP block issues are common in shared hosting servers and cPanel VPSs. Today, let’s take a look at how these IP block issues happen and how we prevent valid IPs from getting blocked.
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What is an IP block? When does it pose a problem?
IP blocks are often helpful in protecting your servers from attacks. They help to ban undesired connections to the server from an IP or location or a network, as a security measure.
The default settings of the cPanel CSF/LFD firewall is to allow only those average website users who possess a few email accounts and follow less site update intervals.
While IP blocks help to ban malicious users from attacking the server, if the firewall rules are set too tight, valid users may also be affected and can find it difficult to access their sites. For instance,
- Users who violate mod-security rules unknowingly or exceed the limit of allowed connections requests occasionally, may be blocked by the firewall.
- Many of these IP blocks in shared servers are also caused by incorrect logins, users saving old passwords in their applications or over-zealous web application firewall settings.
As even a few failed logins can lead to the valid customer IP addresses being blocked, in our cPanel server management services, we audit all firewall logs once a week to make sure valid requests are not blocked.
Whenever we observe a change in the server traffic pattern, we update the firewall rules to avoid blocking valid customers. Here’s an overview of how unwanted cPanel IP block issues are investigated, resolved and prevented.
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IP block issues – causes and symptoms
While automated IP block software such as firewalls provide predictable and consistent performance, they lack judgment, adaptability and logic. That’s why expert human intervention is needed to avoid valid IPs being blocked.
When a valid user IP is blocked, that website owner gets a “Connection timed out” error for Mail, Web, FTP or Control Panel services, while others may be able to access those services fine. This usually happens in the following situations:
- The web owner’s mail client has a very low “mail check interval”, causing multiple connection attempts to the mail server, especially if many users are accessing mail through a common connection.
- The web owner using an old or wrong password in mail, web, FTP or cPanel services interface multiple times, leading the firewall to think it is a brute force attack.
- The web owner has an FTP client set with very high number of simultaneous connections, causing the firewall to treat the connection attempts as a denial of service attack.
- A website or application update or a page access request gets interpreted as a hack attempt by the web application firewall such as mod_security.
While one or two IP block issues per month is normal for a shared server, if too many customers report the issue, then we conclude that the firewall settings are too tight for seamless customer access.
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