How to Configure Your Firewall for cPanel & WHM Services

Valid for versions 94 through the latest version

Version:

84

86

90

92

94

Overview

cPanel & WHM installs and manages many different services on your system, most of which require an external connection in order to function properly. Because of this, your firewall must allow cPanel & WHM to open the ports on which these services run.

This document lists the ports that cPanel & WHM uses, and which services use each of these ports, to allow you to better configure your firewall.

Warning:
  • We strongly recommend that you only open ports for services that you use.
  • When you work with firewall rules, always make certain to include a way to log back in to your server, and always maintain console access to your server.

Ports

Warning:

We strongly recommend that you use the SSL version of each service whenever possible:

  • The use of non-SSL services can allow attackers to intercept sensitive information, such as login credentials.
  • Always ensure that valid SSL certificates exist for your services in WHM’s Manage Service SSL Certificates interface (WHM >> Home >> Service Configuration >> Manage Service SSL Certificates).
Note:

For more information on how to access cPanel & WHM services, read our How to Access cPanel & WHM Services documentation.

cPanel & WHM uses the following ports:

Port Service TCP UDP Inbound Outbound Localhost Notes
1 CPAN The Show Available Modules setting in cPanel’s Perl Modules interface (cPanel >> Home >> Software >> Perl Modules) uses this port to improve the speed in which it appears.
20 FTP Instead of FTP, we recommend that you use the more-secure SFTP via SSH.
21 FTP
22 SSH You must open this port before you use WHM’s Transfer Tool interface (WHM >> Home >> Transfers >> Transfer Tool) when:
  • You authenticate root users with SSH keys.
  • You are transferring from a server on cPanel & WHM version 88 or earlier.
25 SMTP
26 SMTP cPanel & WHM only uses this port if you specify it in WHM’s Service Manager interface (WHM >> Home >> Service Configuration >> Service Manager).
37 rdate
43 whois
53 DNS cPanel & WHM uses this port for the following functions:
  • Public DNS services.
  • Communication with root nameservers for AutoSSL.
  • Other functions that require name resolution.
80 httpd This port serves the HTTP needs of services on the server.
Important:
  • We strongly recommend that you encourage your users to use port 443, which uses the more secure SSL/TLS security protocol. For more information, read our More about TLS and SSL documentation.
  • The cPanel Server Daemon (cpsrvd) listens on this port when you disable the Web Server role. This daemon monitors cPanel & WHM services.
110 POP3
113 ident
143 IMAP
443 httpd This port serves the HTTPS needs of services on the server.
Note:
  • This port can allow users to access cPanel or WHM via certain subdomains. For more information, read our Service and Proxy Subdomains documentation.
  • The cPanel Server Daemon (cpsrvd) listens on this port when you disable the Web Server role.
  • WHM’s Manage AutoSSL interface (WHM >> Home >> SSL/TLS >> Manage AutoSSL) requires outbound access to the store.cpanel.net server.
465 SMTP, SSL/TLS
Important:
cPanel & WHM strongly recommends that you enable Transport Layer Security (TLS) protocol version 1.2 on your server.
579 cPHulk This port should only accept connections on the 127.0.0.x IPv4 address. Your system does not require that this port accept external traffic.
587 Exim
783 Apache SpamAssassin
873 rsync
953 PowerDNS This port should only accept connections on the 127.0.0.1 IPv4 address. Your system does not require that this port accept external traffic.
Note:
You must use this port when you run PowerDNS nameservers.
993 IMAP SSL
995 POP3 SSL
2077 WebDAV cPanel’s Web Disk interface (cPanel >> Home >> Files >> Web Disk) uses these ports.
2078 WebDAV SSL
2079 CalDAV and CardDAV
2080 CalDAV and CardDAV (SSL)
2082 cPanel and cPanel Licensing
Note:
To disable logins via this port and only allow SSL logins, set the Choose the closest matched domain for which that the system has a valid certificate when redirecting from non-SSL to SSL URLs. Formerly known as “Always redirect to SSL/TLS” setting to On in WHM’s Tweak Settings interface (WHM >> Home >> Server Configuration >> Tweak Settings). This will redirect users to secure ports with the /cpanel, /whm, and /webmail aliases.
2083 cPanel SSL and cPanel Licensing
2086 WHM and cPanel Licensing
Note:
To disable logins via this port and only allow SSL logins, set the Choose the closest matched domain for which that the system has a valid certificate when redirecting from non-SSL to SSL URLs. Formerly known as “Always redirect to SSL/TLS” setting to On in WHM’s Tweak Settings interface (WHM >> Home >> Server Configuration >> Tweak Settings). This will redirect users to secure ports with the /cpanel, /whm, and /webmail aliases.
2087 WHM SSL and cPanel Licensing
2089 cPanel Licensing
Important:
You must configure your system to permit outbound tcp connections from source ports 4 and 1020 to destination port 2089. This will allow the server to contact the cPanel, L.L.C. license servers.
2095 Webmail
Note:
To disable logins via this port and only allow SSL logins, set the Choose the closest matched domain for which that the system has a valid certificate when redirecting from non-SSL to SSL URLs. Formerly known as “Always redirect to SSL/TLS” setting to On in WHM’s Tweak Settings interface (WHM >> Home >> Server Configuration >> Tweak Settings). This will redirect users to secure ports with the /cpanel, /whm, and /webmail aliases.
2096 Webmail SSL and cPanel Licensing
2195 Apple Push Notification service (APNs) cPanel & WHM only uses this port for the Apple® Push Notification Service (APNs). For more information, read our How to Set Up iOS Push Notifications documentation.
2703 Razor Razor is a collaborative spam-tracking database.
3306 MySQL® MySQL uses this port for remote database connections.
6277 DCC For more information, read the Apache® DCC and NetTestFirewallIssues documentation.
24441 Pyzor For more information, read Apache’s Pyzor and NetTestFirewallIssues documentation.

The License Callback Mechanism

The License Callback Mechanism immediately updates a server after the license changes in either Manage2 or the cPanel Store. It cannot make any changes to the server. It only alerts the server that a change as been made to the license. The license callback mechanism tries the following ports until one succeeds:

Service Port Inbound Outbound
cPanel 2082
cPanel SSL 2083
WHM 2086
WHM SSL 2087
Webmail SSL 2096
Note:

At least one port in the above table must be open for the license callback mechanism to work. The server only accepts requests to this API from cPanel & WHM. The license system does not send any other information to the customer’s server.

Example configurations

Important:
  • We do not recommend that you use these examples for your personal configurations. Instead, make certain that your firewall rules match the way in which you use cPanel & WHM’s services.
  • CentOS 8, AlmaLinux 8, and CloudLinux 8 servers have additional requirements. For more information, read the CentOS 8, AlmaLinux 8, and CloudLinux 8 firewall management section below.
  • CentOS 7, CloudLinux 7, and Red Hat® Enterprise Linux® (RHEL) 7 servers have additional requirements. For more information, read the CentOS 7, CloudLinux 7, and RHEL 7 firewall management section below.
  • Red Hat Enterprise Linux 8 deprecated the iptables utility. While cPanel, L.L.C. does not support this version of RHEL, this change affects all cPanel-supported operating systems. We recommend the nftables utility for servers that run CentOS 8, AlmaLinux 8, or CloudLinux 8. For servers that run CentOS 7, CloudLinux 7, or RHEL 7, we recommend that you use the firewalld utility. For more information, read Red Hat’s When to use firewalld, nftables, or iptables documentation.

CentOS 8, AlmaLinux 8, and CloudLinux 8 firewall management

Important:

We strongly recommend that you use the nftables framework for your CentOS 8, AlmaLinux 8, or CloudLinux 8 firewall.

Use the nftables framework instead of iptables programs or legacy services in those operating systems. You can configure nftables with the nft command line tool. You will find the nftables ruleset for your server in the /etc/sysconfig/nftables.conf file.

For example, to block traffic for a single IPv4 address, run the following command, where 192.168.0.0 is the IPv4 address that you wish to block:

nft add rule filter INPUT ip saddr 192.168.0.0 drop

To block traffic for a single IPv6 address, run the following command, where 2001:0db8:0:0:1:0:0:1 is the IPv6 address that you wish to block:

nft add rule ip6 filter INPUT ip6 saddr [2001:0db8:0:0:1:0:0:1] drop

For more information about the nftables framework and the nft tool, read Red Hat’s Getting Started with nftables documentation.

CentOS 7, CloudLinux 7, and RHEL 7 firewall management

We strongly recommend that servers which run the CentOS 7, CloudLinux 7, and RHEL 7 operating systems use the firewalld daemon instead of iptables programs or legacy services in those operating systems.

For example, to block traffic for a single IPv4 address, run the following command, where 192.168.0.0 is the IPv4 address that you wish to block:

firewall-cmd --add-rich-rule='rule family="ipv4" source address="192.168.0.0" drop' --permanent

To block traffic for a single IPv6 address, run the following command, where 2001:0db8:0:0:1:0:0:1 is the IPv6 address that you wish to block:

firewall-cmd --add-rich-rule='rule family="ipv6" source address="[2001:0db8:0:0:1:0:0:1]" drop' --permanent
Important:

We recommend that you only use the firewall utilities on CentOS 7, CloudLinux 7, and RHEL 7 servers.

  • If you use firewalld, you must enable the daemon before you change the firewall settings. To do this, run the systemctl enable firewalld command. If you do not enable the daemon, the system will erase any firewall changes when you reboot the server.
  • If you use firewalld, the system will remove the ipables-services package through the yum package manager with the following command: yum remove iptables-service
  • If you use the the legacy iptables service, remove the firewalld package through the yum package manager with the following command: yum remove firewalld
  • If you use a third-party firewall management service, we recommend that you check the firewall’s documentation before you remove the unused firewalld or iptables services.

For more information about the firewall utilities and the firewalld daemon, read Red Hat’s Using Firewalls documentation.

The cpanel service

Important:

The /usr/local/cpanel/scripts/configure_firewall_for_cpanel script clears all existing entries from the iptables application. If you use custom rules for your firewall, export those rules before you run the script and then re-add them afterward.

cPanel & WHM also includes the cpanel service, which manages all of the rules in the /etc/firewalld/services/cpanel.xml file. This allows TCP access for the server’s ports.

To replace your existing iptables rules with the rules in the /etc/firewalld/services/cpanel.xml file, perform the following steps:

  1. Run the yum install firewalld command to ensure that you have installed the firewalld service daemon on your system.
  2. Run the systemctl start firewalld.service command to start the firewalld service.
  3. Run the systemctl enable firewalld command to start the firewalld service when the server starts.
  4. Run the iptables-save > backupfile command to save your existing firewall rules.
  5. Run the /usr/local/cpanel/scripts/configure_firewall_for_cpanel script.
  6. Run the iptables-restore < backupfile command to incorporate your old firewall rules into the new firewall rules file.

Adding rules with the iptables utility

The following examples explain how to add rules with ConfigServer Security & Firewall (CSF), Advanced Policy Firewall (APF), and the iptables utility.

Remember:

Red Hat Enterprise Linux 8 deprecated the iptables utility. While cPanel, L.L.C. does not support this version of RHEL, this change affects all cPanel-supported operating systems. We recommend the nftables utility for servers that run CentOS 8, AlmaLinux 8, or CloudLinux 8. For servers that run CentOS 7, CloudLinux 7, or RHEL 7, we recommend that you use the firewalld utility.

For more information, read Red Hat’s When to use firewalld, nftables, or iptables documentation.

ConfigServer Security & Firewall

ConfigServer provides the free WHM plugin ConfigServer Security & Firewall, which allows you to modify your iptables rules within WHM. For information about how to install and configure CSF, read our Additional Security Software documentation.

Advanced Policy Firewall

Advanced Policy Firewall (APF) acts as a front-end interface for the iptables application, and allows you to open or close ports without the use of the iptables syntax.

The following example includes two rules that you can add to the /etc/apf/conf.apf file in order to allow HTTP and HTTPS access to your system:

1
2
3

# Common ingress (inbound) TCP ports
IG_TCP_CPORTS="80,443"
EG_TCP_CPORTS="80"

iptables

The iptables application offers more customization settings for your packet filtering rules. This application requires that you understand the TCP/IP stack. For more information about the use of iptables, visit the iptables site, or run the man iptables command from the command line.

The following example includes iptables rules for HTTP traffic on port 80:

1
2

$IPTABLES -A FORWARD -p TCP -i 66.66.66.66 -o eth0 -d 192.168.1.1 -dport 80 -j allowed
$IPTABLES -A FORWARD -p ICMP -i 66.66.66.66 -o eth0 -d 192.168.1.1 -j icmp_packets
Note:

This example assumes that a DMZ exists on eth0 for the 192.168.1.1 port, and the 66.66.66.66 broadcast IP address.