Dependencies ¶

To ensure ConfigServer Firewall & Security (CSF) functions correctly, all required dependencies must be installed. Some dependencies are essential for the core operation of CSF, while others are only necessary if you plan to use specific optional features.

Install¶

For our documentation, we are going to include all packages you will need in order to run all functionality within CSF. A lot of the packages listed below will be installed along with the base perl package; however, we've included them to ensure nothing gets left behind.

Minimal Dependencies¶

The following are a list of the minimal dependencies required for CSF to function. This does not include packages such as gd library which are required if you plan to make use of the statistics feature which is enabled in the /etc/csf/csf.conf with the setting ST_ENABLE = "1".

Debian/Ubuntu (apt-get) CentOS/RHEL (yum/dnf) Perl (CPAN) Perl (CPANMINUS)

# #
#   Minimum Dependencies
# #

sudo apt-get update && sudo apt-get install -y \
  perl \
  libwww-perl \
  libio-socket-ssl-perl \
  libcrypt-ssleay-perl \
  libnet-libidn-perl \
  libio-socket-inet6-perl \
  libsocket6-perl

# #
#   Minimum Dependencies
# #

sudo yum makecache && sudo yum install -y \
  perl \
  perl-libwww-perl \
  perl-IO-Socket-SSL \
  perl-Net-SSLeay \
  perl-Net-LibIDN \
  perl-IO-Socket-INET6 \
  perl-Socket6

# #
#   Debian/Ubuntu
# #

sudo apt-get update && sudo apt-get install -y perl

# #
#   CentOS/RHEL
# #

sudo yum makecache && sudo yum install -y perl

# #
#   Minimum Dependencies
# #

sudo cpan -i \
  LWP \
  IO::Socket::SSL \
  Net::SSLeay \
  Net::LibIDN \
  IO::Socket::INET6 \
  Socket6

# #
#   Debian/Ubuntu
# #

sudo apt-get update && sudo apt-get install -y perl cpanminus

# #
#   CentOS/RHEL
# #

sudo yum makecache && sudo yum install -y perl perl-App-cpanminus

# #
#   Minimum Dependencies
# #

sudo cpanm \
  LWP \
  IO::Socket::SSL \
  Net::SSLeay \
  Net::LibIDN \
  IO::Socket::INET6 \
  Socket6

Full Dependencies¶

The following commands allow you to install the full list of dependencies for CSF which include packages for every feature shipped with CSF, including the statistics feature which is enabled in the /etc/csf/csf.conf with the setting ST_ENABLE = "1".

This set of dependencies also includes sendmail to make use of CSF's mailing functionality.

Debian/Ubuntu (apt-get) CentOS/RHEL (yum/dnf) Perl (CPAN) Perl (CPANMINUS)

# #
#   Full Dependencies
# #

sudo apt-get update && sudo apt-get install -y \
  perl \
  libio-socket-ssl-perl \
  libwww-perl \
  libjson-perl \
  libnet-ssleay-perl \
  libcrypt-ssleay-perl \
  liblwp-protocol-https-perl \
  libgd-graph-perl \
  libio-socket-inet6-perl \
  libsocket6-perl \
  libnet-libidn-perl \
  libtime-hires-perl \
  sendmail \
  dnsutils \
  unzip \
  wget

# #
#   Full Dependencies
# #

sudo yum install -y \
  perl \
  perl-IO-Socket-SSL.noarch \
  perl-Net-SSLeay \
  perl-Net-LibIDN \
  perl-IO-Socket-Inet6 \
  perl-Socket6 \
  perl-libwww-perl \
  perl-JSON \
  perl-LWP-Protocol-https.noarch \
  perl-GDGraph \
  perl-Math-BigInt \
  perl-Time-HiRes \
  perl-Socket \
  net-tools \
  sendmail \
  ipset \
  bind-utils \
  wget \
  unzip

For the Statistics feature, ensure GD C library headers are installed first:

Debian/Ubuntu: sudo apt-get install -y libgd-dev
RHEL/CentOS: sudo yum install -y gd-devel

# #
#   Debian/Ubuntu
# #

sudo apt-get update && sudo apt-get install -y perl libgd-dev

# #
#   CentOS/RHEL
# #

sudo yum makecache && sudo yum install -y epel-release perl gd-devel

# #
#   Full Dependencies
# #

sudo cpan -i \
  LWP \
  IO::Socket::SSL \
  Net::SSLeay \
  Net::LibIDN \
  IO::Socket::INET6 \
  Socket6 \
  LWP::Protocol::https \
  LWP::UserAgent \
  JSON \
  Crypt::SSLeay \
  Digest::MD5 \
  Digest::SHA \
  Email::Valid \
  GD::Graph \
  Time::HiRes \
  Socket

For the Statistics feature, ensure GD C library headers are installed first:

Debian/Ubuntu: sudo apt-get install -y libgd-dev
RHEL/CentOS: sudo yum install -y gd-devel

# #
#   Debian/Ubuntu
# #

sudo apt-get update && sudo apt-get install -y perl libgd-dev cpanminus

# #
#   CentOS/RHEL
# #

sudo yum makecache && sudo yum install -y epel-release perl gd-devel perl-App-cpanminus

# #
#   Full Dependencies
# #

sudo cpanm \
  LWP \
  IO::Socket::SSL \
  Net::SSLeay \
  Net::LibIDN \
  IO::Socket::INET6 \
  Socket6 \
  LWP::Protocol::https \
  LWP::UserAgent \
  JSON \
  Crypt::SSLeay \
  Digest::MD5 \
  Digest::SHA \
  Email::Valid \
  GD::Graph \
  Time::HiRes \
  Socket

Optional Dependencies¶

If you decided to opt for the Full Dependencies install above, you do not need to do this step since the full dependency instructions already include these packages.

Email Alerts¶

CSF can send email alerts for blocked IPs, login failures, or other events. To enable this functionality, you need a working Mail Transfer Agent (MTA) such as sendmail or postfix.

Important Notes to Remember

The following should be taken into consideration when installing the dependencies for email alerts:

After installing sendmail, ensure the MTA is enabled and running:
Debian/Ubuntu: sudo systemctl enable --now sendmail
RHEL/CentOS: sudo systemctl enable --now sendmail
You can also use postfix or another MTA if preferred — CSF will use whatever MTA is configured on the system.
This is optional if you do not need email alerts, but it is highly recommended for security monitoring.

Debian/Ubuntu (apt-get) CentOS/RHEL (yum/dnf)

sudo apt-get update && sudo apt-get install -y sendmail

sudo yum makecache && sudo yum install -y sendmail

Statistics / Graphs¶

CSF comes with an optional feature which allows you to generate charts / graphs that can show Statistics for your server. In order to generate these charts, a few packages are required.

To enable Statistics (ST_ENABLE = "1"), you need the following:
- GD Graphics Library (libgd)
  - C library for creating and manipulating images (PNG, JPEG, GIF, etc.).
  - Provides low-level graphics functions for CSF statistics.
  - Debian/Ubuntu: installing the Perl module GD::Graph Perl Module below will automatically pull in the necessary GD library.
  - RHEL/CentOS: you may need gd-devel.
- GD::Graph Perl Module
  - Perl module that depends on the GD library.
  - Provides an API to draw charts and graphs (line, bar, pie, etc.) in Perl scripts.
  - Used by CSF to render statistics graphs in the web interface.
  - Debian/Ubuntu: install via (libgd-graph-perl or CPAN/CPANM.
  - RHEL/CentOS: install via perl-GDGraph or CPAN/CPANM.

Debian/Ubuntu (apt-get) CentOS/RHEL (yum/dnf) Perl (CPAN) Perl (CPANMINUS)

# Install GD Graphics Library (C library) — usually pulled in automatically
sudo apt-get update && sudo apt-get install -y libgd-dev

# Install GD::Graph Perl module
sudo apt-get install -y libgd-graph-perl

# Install GD Graphics Library (C library) — usually pulled in automatically
sudo yum makecache && sudo yum install -y gd-devel

# Install GD::Graph Perl module
sudo yum install -y perl-GDGraph

# Install GD::Graph Perl module (requires libgd-dev already installed)
sudo cpan -i GD::Graph

# Install GD::Graph Perl module (requires libgd-dev already installed)
sudo cpanm GD::Graph

Blocklists¶

CSF allows you to manage blocklists, which are lists of IP addresses that should be denied access to your server. Blocklists can come from official CSF sources or from third-party vendors, and they help automate the process of blocking potentially harmful traffic.

Blocklists can be handled in two ways:

Standard iptables rules: Each IP in the blocklist generates its own iptables rule when CSF starts. This works well for small lists but can become resource-intensive for lists with thousands of entries.
IPSET integration: If IPSET is installed and enabled in the CSF configuration, each IP in the blocklist is added to an IPSET set. CSF then loads these IPSET lists instead of creating individual iptables rules. This method is much more efficient and reduces system resource usage for large blocklists.

If you would like to utilize CSF's built in IPSET integration, you will need to install the required dependencies:

Debian/Ubuntu (apt-get) CentOS/RHEL (yum/dnf)

sudo apt-get update && sudo apt-get install -y ipset

sudo yum install -y epel-release
sudo yum makecache && sudo yum install -y ipset

This section does not go into detailed instructions on how to set up Blocklists or IPSET, however, if you want to read the full instructions for setting this up, review the chapters Introduction to IPSETs and Setting Up Blocklists.

Introduction to IPSETs

Setting Up Blocklists

DNS Lookups¶

CSF supports optional DNS Lookups, which allow the firewall to resolve IP addresses into hostnames and perform reverse lookups. This can be useful for logging, reporting, or applying rules based on domain names rather than just IP addresses. For example, CSF can show resolved hostnames in alert emails or in the web interface, making it easier to understand who is connecting to your server.

Additionally, the csf -g and csf -a commands can use DNS lookups if the required packages are installed, allowing IP addresses to be automatically resolved to hostnames when searching or adding entries.

To enable DNS lookups, CSF requires the dnsutils package (on Debian/Ubuntu) or bind-utils (on RedHat/CentOS). These packages provide tools such as dig and nslookup that CSF uses to perform DNS queries.

Debian/Ubuntu (apt-get) CentOS/RHEL (yum/dnf)

sudo apt-get update && sudo apt-get install -y dnsutils

sudo yum makecache && sudo yum install -y bind-utils

GeoIP Blocking¶

GeoIP Blocking in CSF allows you to block or allow traffic based on the country of origin. This is useful for restricting access to your server from certain regions or implementing geo-specific rules.

This feature does not require a traditional system package to function. Instead, it relies on external databases that map IP addresses to countries.

You have two options for providing these databases:

MaxMind GeoLite2 Databases
DB-IP, ipdeny.com, or iptoasn.com

If you opt to use MaxMind, you can automate the database updates by installing the following:

Debian/Ubuntu (apt-get) CentOS/RHEL (yum/dnf)

sudo add-apt-repository ppa:maxmind/ppa
sudo apt update
sudo apt install geoipupdate

sudo yum install -y epel-release
sudo yum makecache
sudo yum install -y geoipupdate

This section does not go into detailed instructions on how to set up GeoIP blocking, however, if you want to read the full instructions for setting this up, review the chapter Geographical IP Block Integration.

Geographical IP Block Integration

Next Steps ¶

Select what documentation you would like to proceed with next ...

Download CSF

The next part of the guide shows how to download csf from our official sources, such as the GitHub repository, and place it on your server.

It covers using curl or wget to fetch the files, as well as extracting them using either the traditional tar.gz method or the newer zip format.

This step is essential to prepare your server for installing CSF and configuring the firewall.