How to Install ConfigServer Firewall (CSF) on Ubuntu

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What is a Firewall?

Broadly speaking, a firewall is part of a network or server that is designed to restrict potentially malicious and unauthorized access to the hardware while still allowing outward communication from the network or server. 

There are two types of firewalls; physical hardware firewalls which are devices that connect to the destination server and stop traffic from passing to it and, software-based firewalls that run on a server and filter/reject connection attempts. In both cases, the firewall is at its core, a security measure meant to protect your data from unauthorized access. Today, we are going to review how to install CSF Firewall on a Ubuntu server 

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How To Unblock Your IP Address in Manage

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Liquid Web has introduced a new feature designed to simplify the removal of errant IP address blocks in the firewall, and allow customers to quickly remove their own address from within their Manage dashboard. In this manner, customers can remove blocks on their IP addresses even when they are unable to access WebHost Manager itself due to the block.

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Basic DoS/DDoS Mitigation with the CSF Firewall

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Denial of Service (DoS) and Distributed Denial of Service (DDoS) attacks are common threats that every publicly accessible web server faces. The purpose of such attacks, in simplest terms, is to flood a server with connections, overloading it and preventing from accepting legitimate traffic.

Attacks increasingly have become automated instead of directly targeted and botnets (networks of infected computers that can be remotely controlled) continue to grow at a rapid pace, making DoS and DDoS attacks much more common.

Fortunately, CSF can be used to help mitigate small attacks. Continue reading “Basic DoS/DDoS Mitigation with the CSF Firewall”

How to Block or Allow Specific Ports by Country in the CSF Firewall

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In addition to being able to manage traffic from a specific country or a list of countries, CSF allows you to manage access by country to specific ports. This can be useful if you need to ensure that a particular service is available globally (such as your web server on port 80) but want to restrict international access to services such as WHM/cPanel, SSH, or FTP. Continue reading “How to Block or Allow Specific Ports by Country in the CSF Firewall”

How to Allow Traffic by Country in the CSF Firewall

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One of the most-requested features on cPanel servers is the ability to manage and filter traffic at a country level. With the ConfigServer Firewall (CSF) plugin in WebHost Manager, you can do exactly that. Continue reading “How to Allow Traffic by Country in the CSF Firewall”

How to Block Traffic by Country in the CSF Firewall

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One of the most-requested features on cPanel servers is the ability to manage and filter traffic at a country level. With the ConfigServer Firewall (CSF) plugin in WebHost Manager, you can do exactly that.

Country-level filtering in CSF uses the Maxmind GeoLite Country database to obtain CIDR (Classless Inter-Domain Routing) ranges for specific countries. Each CIDR range covers all the IP addresses assigned to that country. Continue reading “How to Block Traffic by Country in the CSF Firewall”

How to Back up and Restore the CSF Firewall Configuration

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Prior to making direct edits to the firewall configuration file or changing advanced firewall settings in WHM, a backup of the current configuration should be taken so that the settings can quickly and easily be reverted if needed. Continue reading “How to Back up and Restore the CSF Firewall Configuration”

Unblocking an IP Address or Opening a Port in the Firewall

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Should you discover (or suspect) that a client or customer’s IP address has been blocked by the firewall on your cPanel server, or should you just need to open or close a port, you may be able to quickly resolve the issue yourself with just a little help. Continue reading “Unblocking an IP Address or Opening a Port in the Firewall”

How To Unblock an IP Address in APF

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Advanced Policy Firewall, or APF, is a software firewall commonly installed on Liquid Web servers. It is an interface to iptables, which is standard software for managing network ports on Linux. Interacting with iptables can be complex, but APF greatly simplifies the process. APF is only accessible via ssh, and there is no way to make changes in APF through WHM or cPanel.

Pre-Flight Check
  • These instructions are intended specifically for unblocking an IP Address in APF.
  • I’ll be working from a Liquid Web Core Managed CentOS 6.5 server, and I’ll be logged in as root.
  • For further details, see our in-depth look at the APF firewall.
Check APF for Your IP Address

Let’s say that you want to check whether or not a specific IP address, maybe 8.8.8.8 , is blocked by APF. That’s easy!

grep 8.8.8.8 /etc/apf/*

You may receive a result similar to:

/etc/apf/deny_hosts.rules:# added 8.8.8.8 on 04/25/14 13:42:01 with comment: {bfd.courier}
/etc/apf/deny_hosts.rules:8.8.8.8

The above means that BFD detected a brute force attack from the IP 8.8.8.8 on port 25, and automatically added a rule to APF to prevent future connections specifically from that IP address.

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