\documentclass[10pt,a4paper]{article}

% Packages
\usepackage{fancyhdr}           % For header and footer
\usepackage{multicol}           % Allows multicols in tables
\usepackage{tabularx}           % Intelligent column widths
\usepackage{tabulary}           % Used in header and footer
\usepackage{hhline}             % Border under tables
\usepackage{graphicx}           % For images
\usepackage{xcolor}             % For hex colours
%\usepackage[utf8x]{inputenc}    % For unicode character support
\usepackage[T1]{fontenc}        % Without this we get weird character replacements
\usepackage{colortbl}           % For coloured tables
\usepackage{setspace}           % For line height
\usepackage{lastpage}           % Needed for total page number
\usepackage{seqsplit}           % Splits long words.
%\usepackage{opensans}          % Can't make this work so far. Shame. Would be lovely.
\usepackage[normalem]{ulem}     % For underlining links
% Most of the following are not required for the majority
% of cheat sheets but are needed for some symbol support.
\usepackage{amsmath}            % Symbols
\usepackage{MnSymbol}           % Symbols
\usepackage{wasysym}            % Symbols
%\usepackage[english,german,french,spanish,italian]{babel}              % Languages

% Document Info
\author{hlhlhl (hlhlhl)}
\pdfinfo{
  /Title (linux-firewalls.pdf)
  /Creator (Cheatography)
  /Author (hlhlhl (hlhlhl))
  /Subject (Linux Firewalls Cheat Sheet)
}

% Lengths and widths
\addtolength{\textwidth}{6cm}
\addtolength{\textheight}{-1cm}
\addtolength{\hoffset}{-3cm}
\addtolength{\voffset}{-2cm}
\setlength{\tabcolsep}{0.2cm} % Space between columns
\setlength{\headsep}{-12pt} % Reduce space between header and content
\setlength{\headheight}{85pt} % If less, LaTeX automatically increases it
\renewcommand{\footrulewidth}{0pt} % Remove footer line
\renewcommand{\headrulewidth}{0pt} % Remove header line
\renewcommand{\seqinsert}{\ifmmode\allowbreak\else\-\fi} % Hyphens in seqsplit
% This two commands together give roughly
% the right line height in the tables
\renewcommand{\arraystretch}{1.3}
\onehalfspacing

% Commands
\newcommand{\SetRowColor}[1]{\noalign{\gdef\RowColorName{#1}}\rowcolor{\RowColorName}} % Shortcut for row colour
\newcommand{\mymulticolumn}[3]{\multicolumn{#1}{>{\columncolor{\RowColorName}}#2}{#3}} % For coloured multi-cols
\newcolumntype{x}[1]{>{\raggedright}p{#1}} % New column types for ragged-right paragraph columns
\newcommand{\tn}{\tabularnewline} % Required as custom column type in use

% Font and Colours
\definecolor{HeadBackground}{HTML}{333333}
\definecolor{FootBackground}{HTML}{666666}
\definecolor{TextColor}{HTML}{333333}
\definecolor{DarkBackground}{HTML}{A3A3A3}
\definecolor{LightBackground}{HTML}{F3F3F3}
\renewcommand{\familydefault}{\sfdefault}
\color{TextColor}

% Header and Footer
\pagestyle{fancy}
\fancyhead{} % Set header to blank
\fancyfoot{} % Set footer to blank
\fancyhead[L]{
\noindent
\begin{multicols}{3}
\begin{tabulary}{5.8cm}{C}
    \SetRowColor{DarkBackground}
    \vspace{-7pt}
    {\parbox{\dimexpr\textwidth-2\fboxsep\relax}{\noindent
        \hspace*{-6pt}\includegraphics[width=5.8cm]{/web/www.cheatography.com/public/images/cheatography_logo.pdf}}
    }
\end{tabulary}
\columnbreak
\begin{tabulary}{11cm}{L}
    \vspace{-2pt}\large{\bf{\textcolor{DarkBackground}{\textrm{Linux Firewalls Cheat Sheet}}}} \\
    \normalsize{by \textcolor{DarkBackground}{hlhlhl (hlhlhl)} via \textcolor{DarkBackground}{\uline{cheatography.com/218585/cs/48356/}}}
\end{tabulary}
\end{multicols}}

\fancyfoot[L]{ \footnotesize
\noindent
\begin{multicols}{3}
\begin{tabulary}{5.8cm}{LL}
  \SetRowColor{FootBackground}
  \mymulticolumn{2}{p{5.377cm}}{\bf\textcolor{white}{Cheatographer}}  \\
  \vspace{-2pt}hlhlhl (hlhlhl) \\
  \uline{cheatography.com/hlhlhl} \\
  \end{tabulary}
\vfill
\columnbreak
\begin{tabulary}{5.8cm}{L}
  \SetRowColor{FootBackground}
  \mymulticolumn{1}{p{5.377cm}}{\bf\textcolor{white}{Cheat Sheet}}  \\
   \vspace{-2pt}Published 6th August, 2026.\\
   Updated 6th August, 2026.\\
   Page {\thepage} of \pageref{LastPage}.
\end{tabulary}
\vfill
\columnbreak
\begin{tabulary}{5.8cm}{L}
  \SetRowColor{FootBackground}
  \mymulticolumn{1}{p{5.377cm}}{\bf\textcolor{white}{Sponsor}}  \\
  \SetRowColor{white}
  \vspace{-5pt}
  %\includegraphics[width=48px,height=48px]{dave.jpeg}
  Measure your website readability!\\
  www.readability-score.com
\end{tabulary}
\end{multicols}}




\begin{document}
\raggedright
\raggedcolumns

% Set font size to small. Switch to any value
% from this page to resize cheat sheet text:
% www.emerson.emory.edu/services/latex/latex_169.html
\footnotesize % Small font.

\begin{multicols*}{3}

\begin{tabularx}{5.377cm}{x{3.13551 cm} x{1.84149 cm} }
\SetRowColor{DarkBackground}
\mymulticolumn{2}{x{5.377cm}}{\bf\textcolor{white}{firewalld (RHEL/Fedora)}}  \tn
% Row 0
\SetRowColor{LightBackground}
{\bf{Command}} & {\bf{Purpose}} \tn 
% Row Count 1 (+ 1)
% Row 1
\SetRowColor{white}
`firewall-cmd -{}-state` & Firewall status \tn 
% Row Count 3 (+ 2)
% Row 2
\SetRowColor{LightBackground}
`firewall-cmd -{}-get-active-zones` & Active zones \tn 
% Row Count 5 (+ 2)
% Row 3
\SetRowColor{white}
`firewall-cmd -{}-list-all` & List zone configuration \tn 
% Row Count 7 (+ 2)
% Row 4
\SetRowColor{LightBackground}
`firewall-cmd -{}-list-services` & Allowed services \tn 
% Row Count 9 (+ 2)
% Row 5
\SetRowColor{white}
`firewall-cmd -{}-list-ports & Open ports \tn 
% Row Count 11 (+ 2)
% Row 6
\SetRowColor{LightBackground}
`firewall-cmd -{}-add-service=http -{}-permanent` & Allow service \tn 
% Row Count 13 (+ 2)
% Row 7
\SetRowColor{white}
`firewall-cmd -{}-remove-service=http -permanent` & Remove service \tn 
% Row Count 15 (+ 2)
% Row 8
\SetRowColor{LightBackground}
`firewall-cmd -{}-add-port=80/tcp -{}-permanent` & Open port \tn 
% Row Count 17 (+ 2)
% Row 9
\SetRowColor{white}
`firewall-cmd -{}-remove-port=80/tcp -{}-permanent` & Close port \tn 
% Row Count 19 (+ 2)
% Row 10
\SetRowColor{LightBackground}
`firewall-cmd -{}-reload` & Reload rules \tn 
% Row Count 20 (+ 1)
\hhline{>{\arrayrulecolor{DarkBackground}}--}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{x{3.03597 cm} x{1.94103 cm} }
\SetRowColor{DarkBackground}
\mymulticolumn{2}{x{5.377cm}}{\bf\textcolor{white}{UFW (Ubuntu)}}  \tn
% Row 0
\SetRowColor{LightBackground}
{\bf{Command}} & {\bf{Purpose}} \tn 
% Row Count 1 (+ 1)
% Row 1
\SetRowColor{white}
`ufw enable` & Enable firewall \tn 
% Row Count 2 (+ 1)
% Row 2
\SetRowColor{LightBackground}
`ufw disable` & Disable firewall \tn 
% Row Count 4 (+ 2)
% Row 3
\SetRowColor{white}
`ufw status` & Show status \tn 
% Row Count 5 (+ 1)
% Row 4
\SetRowColor{LightBackground}
`ufw status verbose` & Detailed status \tn 
% Row Count 6 (+ 1)
% Row 5
\SetRowColor{white}
`ufw allow ssh` & Allow SSH \tn 
% Row Count 7 (+ 1)
% Row 6
\SetRowColor{LightBackground}
`ufw allow 80/tcp` & Allow port \tn 
% Row Count 8 (+ 1)
% Row 7
\SetRowColor{white}
`ufw deny 23` & Deny port \tn 
% Row Count 9 (+ 1)
% Row 8
\SetRowColor{LightBackground}
`ufw delete allow 80/tcp` & Remove rule \tn 
% Row Count 11 (+ 2)
% Row 9
\SetRowColor{white}
`ufw reload` & Reload rules \tn 
% Row Count 12 (+ 1)
% Row 10
\SetRowColor{LightBackground}
`ufw reset` & Reset firewall \tn 
% Row Count 13 (+ 1)
\hhline{>{\arrayrulecolor{DarkBackground}}--}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{x{3.23505 cm} x{1.74195 cm} }
\SetRowColor{DarkBackground}
\mymulticolumn{2}{x{5.377cm}}{\bf\textcolor{white}{IP Forwarding}}  \tn
% Row 0
\SetRowColor{LightBackground}
{\bf{Command}} & {\bf{Purpose}} \tn 
% Row Count 1 (+ 1)
% Row 1
\SetRowColor{white}
`sysctl net.ipv4.ip\_forward` & Check status \tn 
% Row Count 3 (+ 2)
% Row 2
\SetRowColor{LightBackground}
`sysctl -w net.ipv4.ip\_forward=1` & Enable temporarily \tn 
% Row Count 5 (+ 2)
\hhline{>{\arrayrulecolor{DarkBackground}}--}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{x{2.83689 cm} x{2.14011 cm} }
\SetRowColor{DarkBackground}
\mymulticolumn{2}{x{5.377cm}}{\bf\textcolor{white}{iptables (Legacy)}}  \tn
% Row 0
\SetRowColor{LightBackground}
{\bf{Command}} & {\bf{Purpose}} \tn 
% Row Count 1 (+ 1)
% Row 1
\SetRowColor{white}
`iptables -L` & List rules \tn 
% Row Count 2 (+ 1)
% Row 2
\SetRowColor{LightBackground}
`iptables -L -n -v` & Detailed rules \tn 
% Row Count 3 (+ 1)
% Row 3
\SetRowColor{white}
`iptables -F` & Flush rules \tn 
% Row Count 4 (+ 1)
% Row 4
\SetRowColor{LightBackground}
`iptables -A INPUT ...` & Append rule \tn 
% Row Count 6 (+ 2)
% Row 5
\SetRowColor{white}
`iptables -D` & Delete rule \tn 
% Row Count 7 (+ 1)
% Row 6
\SetRowColor{LightBackground}
`iptables -I` & Insert rule \tn 
% Row Count 8 (+ 1)
% Row 7
\SetRowColor{white}
`iptables -P INPUT DROP` & Set default policy \tn 
% Row Count 10 (+ 2)
% Row 8
\SetRowColor{LightBackground}
`iptables-save` & Save rules \tn 
% Row Count 11 (+ 1)
% Row 9
\SetRowColor{white}
`iptables-restore` & Restore rules \tn 
% Row Count 12 (+ 1)
\hhline{>{\arrayrulecolor{DarkBackground}}--}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{X}
\SetRowColor{DarkBackground}
\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{ipset}}  \tn
% Row 0
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{{\bf{Command}}} \tn 
% Row Count 1 (+ 1)
% Row 1
\SetRowColor{white}
\mymulticolumn{1}{x{5.377cm}}{`ipset create`} \tn 
% Row Count 2 (+ 1)
% Row 2
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{`ipset add`} \tn 
% Row Count 3 (+ 1)
% Row 3
\SetRowColor{white}
\mymulticolumn{1}{x{5.377cm}}{`ipset del`} \tn 
% Row Count 4 (+ 1)
% Row 4
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{`ipset list`} \tn 
% Row Count 5 (+ 1)
% Row 5
\SetRowColor{white}
\mymulticolumn{1}{x{5.377cm}}{`ipset destroy`} \tn 
% Row Count 6 (+ 1)
\hhline{>{\arrayrulecolor{DarkBackground}}-}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{x{2.33919 cm} x{2.63781 cm} }
\SetRowColor{DarkBackground}
\mymulticolumn{2}{x{5.377cm}}{\bf\textcolor{white}{NAT}}  \tn
% Row 0
\SetRowColor{LightBackground}
{\bf{Command}} & {\bf{Purpose}} \tn 
% Row Count 1 (+ 1)
% Row 1
\SetRowColor{white}
`iptables -t nat -L` & View NAT table \tn 
% Row Count 3 (+ 2)
% Row 2
\SetRowColor{LightBackground}
`nft list table nat` & View nftables NAT rules \tn 
% Row Count 5 (+ 2)
\hhline{>{\arrayrulecolor{DarkBackground}}--}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{x{3.13551 cm} x{1.84149 cm} }
\SetRowColor{DarkBackground}
\mymulticolumn{2}{x{5.377cm}}{\bf\textcolor{white}{nftables (Modern)}}  \tn
% Row 0
\SetRowColor{LightBackground}
{\bf{Command}} & {\bf{Purpose}} \tn 
% Row Count 1 (+ 1)
% Row 1
\SetRowColor{white}
`nft list ruleset` & Show all rules \tn 
% Row Count 2 (+ 1)
% Row 2
\SetRowColor{LightBackground}
`nft flush ruleset` & Remove all rules \tn 
% Row Count 4 (+ 2)
% Row 3
\SetRowColor{white}
`nft add table inet filter` & Create table \tn 
% Row Count 6 (+ 2)
% Row 4
\SetRowColor{LightBackground}
`nft add chain ...` & Create chain \tn 
% Row Count 7 (+ 1)
% Row 5
\SetRowColor{white}
`nft delete rule ...` & Delete rule \tn 
% Row Count 8 (+ 1)
% Row 6
\SetRowColor{LightBackground}
`nft delete table ...` & Delete table \tn 
% Row Count 9 (+ 1)
\hhline{>{\arrayrulecolor{DarkBackground}}--}
\end{tabularx}
\par\addvspace{1.3em}


% That's all folks
\end{multicols*}

\end{document}