You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
770 lines
48 KiB
770 lines
48 KiB
4 years ago
|
<!DOCTYPE html>
|
||
|
|
<html lang="en">
|
||
|
|
<head>
|
||
|
|
<meta charset="UTF-8">
|
||
|
|
<meta http-equiv="X-UA-Compatible" content="IE=edge">
|
||
|
|
<meta name="viewport" content="width=device-width, initial-scale=1.0">
|
||
|
|
<meta name="generator" content="Asciidoctor 2.0.10">
|
||
|
|
<meta name="description" content="Intro and Install">
|
||
|
|
<meta name="keywords" content="sec, tcpdump">
|
||
|
|
<meta name="author" content="Apostolos rootApostolos@swarmlab.io">
|
||
|
|
<title>Iptables - Traversing of tables and chains!</title>
|
||
|
|
<link rel="stylesheet" href="https://fonts.googleapis.com/css?family=Open+Sans:300,300italic,400,400italic,600,600italic%7CNoto+Serif:400,400italic,700,700italic%7CDroid+Sans+Mono:400,700">
|
||
|
|
<style>
|
||
|
|
/* Asciidoctor default stylesheet | MIT License | https://asciidoctor.org */
|
||
|
|
/* Uncomment @import statement to use as custom stylesheet */
|
||
|
|
/*@import "https://fonts.googleapis.com/css?family=Open+Sans:300,300italic,400,400italic,600,600italic%7CNoto+Serif:400,400italic,700,700italic%7CDroid+Sans+Mono:400,700";*/
|
||
|
|
article,aside,details,figcaption,figure,footer,header,hgroup,main,nav,section{display:block}
|
||
|
|
audio,video{display:inline-block}
|
||
|
|
audio:not([controls]){display:none;height:0}
|
||
|
|
html{font-family:sans-serif;-ms-text-size-adjust:100%;-webkit-text-size-adjust:100%}
|
||
|
|
a{background:none}
|
||
|
|
a:focus{outline:thin dotted}
|
||
|
|
a:active,a:hover{outline:0}
|
||
|
|
h1{font-size:2em;margin:.67em 0}
|
||
|
|
abbr[title]{border-bottom:1px dotted}
|
||
|
|
b,strong{font-weight:bold}
|
||
|
|
dfn{font-style:italic}
|
||
|
|
hr{-moz-box-sizing:content-box;box-sizing:content-box;height:0}
|
||
|
|
mark{background:#ff0;color:#000}
|
||
|
|
code,kbd,pre,samp{font-family:monospace;font-size:1em}
|
||
|
|
pre{white-space:pre-wrap}
|
||
|
|
q{quotes:"\201C" "\201D" "\2018" "\2019"}
|
||
|
|
small{font-size:80%}
|
||
|
|
sub,sup{font-size:75%;line-height:0;position:relative;vertical-align:baseline}
|
||
|
|
sup{top:-.5em}
|
||
|
|
sub{bottom:-.25em}
|
||
|
|
img{border:0}
|
||
|
|
svg:not(:root){overflow:hidden}
|
||
|
|
figure{margin:0}
|
||
|
|
fieldset{border:1px solid silver;margin:0 2px;padding:.35em .625em .75em}
|
||
|
|
legend{border:0;padding:0}
|
||
|
|
button,input,select,textarea{font-family:inherit;font-size:100%;margin:0}
|
||
|
|
button,input{line-height:normal}
|
||
|
|
button,select{text-transform:none}
|
||
|
|
button,html input[type="button"],input[type="reset"],input[type="submit"]{-webkit-appearance:button;cursor:pointer}
|
||
|
|
button[disabled],html input[disabled]{cursor:default}
|
||
|
|
input[type="checkbox"],input[type="radio"]{box-sizing:border-box;padding:0}
|
||
|
|
button::-moz-focus-inner,input::-moz-focus-inner{border:0;padding:0}
|
||
|
|
textarea{overflow:auto;vertical-align:top}
|
||
|
|
table{border-collapse:collapse;border-spacing:0}
|
||
|
|
*,*::before,*::after{-moz-box-sizing:border-box;-webkit-box-sizing:border-box;box-sizing:border-box}
|
||
|
|
html,body{font-size:100%}
|
||
|
|
body{background:#fff;color:rgba(0,0,0,.8);padding:0;margin:0;font-family:"Noto Serif","DejaVu Serif",serif;font-weight:400;font-style:normal;line-height:1;position:relative;cursor:auto;tab-size:4;-moz-osx-font-smoothing:grayscale;-webkit-font-smoothing:antialiased}
|
||
|
|
a:hover{cursor:pointer}
|
||
|
|
img,object,embed{max-width:100%;height:auto}
|
||
|
|
object,embed{height:100%}
|
||
|
|
img{-ms-interpolation-mode:bicubic}
|
||
|
|
.left{float:left!important}
|
||
|
|
.right{float:right!important}
|
||
|
|
.text-left{text-align:left!important}
|
||
|
|
.text-right{text-align:right!important}
|
||
|
|
.text-center{text-align:center!important}
|
||
|
|
.text-justify{text-align:justify!important}
|
||
|
|
.hide{display:none}
|
||
|
|
img,object,svg{display:inline-block;vertical-align:middle}
|
||
|
|
textarea{height:auto;min-height:50px}
|
||
|
|
select{width:100%}
|
||
|
|
.center{margin-left:auto;margin-right:auto}
|
||
|
|
.stretch{width:100%}
|
||
|
|
.subheader,.admonitionblock td.content>.title,.audioblock>.title,.exampleblock>.title,.imageblock>.title,.listingblock>.title,.literalblock>.title,.stemblock>.title,.openblock>.title,.paragraph>.title,.quoteblock>.title,table.tableblock>.title,.verseblock>.title,.videoblock>.title,.dlist>.title,.olist>.title,.ulist>.title,.qlist>.title,.hdlist>.title{line-height:1.45;color:#7a2518;font-weight:400;margin-top:0;margin-bottom:.25em}
|
||
|
|
div,dl,dt,dd,ul,ol,li,h1,h2,h3,#toctitle,.sidebarblock>.content>.title,h4,h5,h6,pre,form,p,blockquote,th,td{margin:0;padding:0;direction:ltr}
|
||
|
|
a{color:#2156a5;text-decoration:underline;line-height:inherit}
|
||
|
|
a:hover,a:focus{color:#1d4b8f}
|
||
|
|
a img{border:0}
|
||
|
|
p{font-family:inherit;font-weight:400;font-size:1em;line-height:1.6;margin-bottom:1.25em;text-rendering:optimizeLegibility}
|
||
|
|
p aside{font-size:.875em;line-height:1.35;font-style:italic}
|
||
|
|
h1,h2,h3,#toctitle,.sidebarblock>.content>.title,h4,h5,h6{font-family:"Open Sans","DejaVu Sans",sans-serif;font-weight:300;font-style:normal;color:#ba3925;text-rendering:optimizeLegibility;margin-top:1em;margin-bottom:.5em;line-height:1.0125em}
|
||
|
|
h1 small,h2 small,h3 small,#toctitle small,.sidebarblock>.content>.title small,h4 small,h5 small,h6 small{font-size:60%;color:#e99b8f;line-height:0}
|
||
|
|
h1{font-size:2.125em}
|
||
|
|
h2{font-size:1.6875em}
|
||
|
|
h3,#toctitle,.sidebarblock>.content>.title{font-size:1.375em}
|
||
|
|
h4,h5{font-size:1.125em}
|
||
|
|
h6{font-size:1em}
|
||
|
|
hr{border:solid #dddddf;border-width:1px 0 0;clear:both;margin:1.25em 0 1.1875em;height:0}
|
||
|
|
em,i{font-style:italic;line-height:inherit}
|
||
|
|
strong,b{font-weight:bold;line-height:inherit}
|
||
|
|
small{font-size:60%;line-height:inherit}
|
||
|
|
code{font-family:"Droid Sans Mono","DejaVu Sans Mono",monospace;font-weight:400;color:rgba(0,0,0,.9)}
|
||
|
|
ul,ol,dl{font-size:1em;line-height:1.6;margin-bottom:1.25em;list-style-position:outside;font-family:inherit}
|
||
|
|
ul,ol{margin-left:1.5em}
|
||
|
|
ul li ul,ul li ol{margin-left:1.25em;margin-bottom:0;font-size:1em}
|
||
|
|
ul.square li ul,ul.circle li ul,ul.disc li ul{list-style:inherit}
|
||
|
|
ul.square{list-style-type:square}
|
||
|
|
ul.circle{list-style-type:circle}
|
||
|
|
ul.disc{list-style-type:disc}
|
||
|
|
ol li ul,ol li ol{margin-left:1.25em;margin-bottom:0}
|
||
|
|
dl dt{margin-bottom:.3125em;font-weight:bold}
|
||
|
|
dl dd{margin-bottom:1.25em}
|
||
|
|
abbr,acronym{text-transform:uppercase;font-size:90%;color:rgba(0,0,0,.8);border-bottom:1px dotted #ddd;cursor:help}
|
||
|
|
abbr{text-transform:none}
|
||
|
|
blockquote{margin:0 0 1.25em;padding:.5625em 1.25em 0 1.1875em;border-left:1px solid #ddd}
|
||
|
|
blockquote cite{display:block;font-size:.9375em;color:rgba(0,0,0,.6)}
|
||
|
|
blockquote cite::before{content:"\2014 \0020"}
|
||
|
|
blockquote cite a,blockquote cite a:visited{color:rgba(0,0,0,.6)}
|
||
|
|
blockquote,blockquote p{line-height:1.6;color:rgba(0,0,0,.85)}
|
||
|
|
@media screen and (min-width:768px){h1,h2,h3,#toctitle,.sidebarblock>.content>.title,h4,h5,h6{line-height:1.2}
|
||
|
|
h1{font-size:2.75em}
|
||
|
|
h2{font-size:2.3125em}
|
||
|
|
h3,#toctitle,.sidebarblock>.content>.title{font-size:1.6875em}
|
||
|
|
h4{font-size:1.4375em}}
|
||
|
|
table{background:#fff;margin-bottom:1.25em;border:solid 1px #dedede}
|
||
|
|
table thead,table tfoot{background:#f7f8f7}
|
||
|
|
table thead tr th,table thead tr td,table tfoot tr th,table tfoot tr td{padding:.5em .625em .625em;font-size:inherit;color:rgba(0,0,0,.8);text-align:left}
|
||
|
|
table tr th,table tr td{padding:.5625em .625em;font-size:inherit;color:rgba(0,0,0,.8)}
|
||
|
|
table tr.even,table tr.alt{background:#f8f8f7}
|
||
|
|
table thead tr th,table tfoot tr th,table tbody tr td,table tr td,table tfoot tr td{display:table-cell;line-height:1.6}
|
||
|
|
h1,h2,h3,#toctitle,.sidebarblock>.content>.title,h4,h5,h6{line-height:1.2;word-spacing:-.05em}
|
||
|
|
h1 strong,h2 strong,h3 strong,#toctitle strong,.sidebarblock>.content>.title strong,h4 strong,h5 strong,h6 strong{font-weight:400}
|
||
|
|
.clearfix::before,.clearfix::after,.float-group::before,.float-group::after{content:" ";display:table}
|
||
|
|
.clearfix::after,.float-group::after{clear:both}
|
||
|
|
:not(pre):not([class^=L])>code{font-size:.9375em;font-style:normal!important;letter-spacing:0;padding:.1em .5ex;word-spacing:-.15em;background:#f7f7f8;-webkit-border-radius:4px;border-radius:4px;line-height:1.45;text-rendering:optimizeSpeed;word-wrap:break-word}
|
||
|
|
:not(pre)>code.nobreak{word-wrap:normal}
|
||
|
|
:not(pre)>code.nowrap{white-space:nowrap}
|
||
|
|
pre{color:rgba(0,0,0,.9);font-family:"Droid Sans Mono","DejaVu Sans Mono",monospace;line-height:1.45;text-rendering:optimizeSpeed}
|
||
|
|
pre code,pre pre{color:inherit;font-size:inherit;line-height:inherit}
|
||
|
|
pre>code{display:block}
|
||
|
|
pre.nowrap,pre.nowrap pre{white-space:pre;word-wrap:normal}
|
||
|
|
em em{font-style:normal}
|
||
|
|
strong strong{font-weight:400}
|
||
|
|
.keyseq{color:rgba(51,51,51,.8)}
|
||
|
|
kbd{font-family:"Droid Sans Mono","DejaVu Sans Mono",monospace;display:inline-block;color:rgba(0,0,0,.8);font-size:.65em;line-height:1.45;background:#f7f7f7;border:1px solid #ccc;-webkit-border-radius:3px;border-radius:3px;-webkit-box-shadow:0 1px 0 rgba(0,0,0,.2),0 0 0 .1em white inset;box-shadow:0 1px 0 rgba(0,0,0,.2),0 0 0 .1em #fff inset;margin:0 .15em;padding:.2em .5em;vertical-align:middle;position:relative;top:-.1em;white-space:nowrap}
|
||
|
|
.keyseq kbd:first-child{margin-left:0}
|
||
|
|
.keyseq kbd:last-child{margin-right:0}
|
||
|
|
.menuseq,.menuref{color:#000}
|
||
|
|
.menuseq b:not(.caret),.menuref{font-weight:inherit}
|
||
|
|
.menuseq{word-spacing:-.02em}
|
||
|
|
.menuseq b.caret{font-size:1.25em;line-height:.8}
|
||
|
|
.menuseq i.caret{font-weight:bold;text-align:center;width:.45em}
|
||
|
|
b.button::before,b.button::after{position:relative;top:-1px;font-weight:400}
|
||
|
|
b.button::before{content:"[";padding:0 3px 0 2px}
|
||
|
|
b.button::after{content:"]";padding:0 2px 0 3px}
|
||
|
|
p a>code:hover{color:rgba(0,0,0,.9)}
|
||
|
|
#header,#content,#footnotes,#footer{width:100%;margin-left:auto;margin-right:auto;margin-top:0;margin-bottom:0;max-width:62.5em;*zoom:1;position:relative;padding-left:.9375em;padding-right:.9375em}
|
||
|
|
#header::before,#header::after,#content::before,#content::after,#footnotes::before,#footnotes::after,#footer::before,#footer::after{content:" ";display:table}
|
||
|
|
#header::after,#content::after,#footnotes::after,#footer::after{clear:both}
|
||
|
|
#content{margin-top:1.25em}
|
||
|
|
#content::before{content:none}
|
||
|
|
#header>h1:first-child{color:rgba(0,0,0,.85);margin-top:2.25rem;margin-bottom:0}
|
||
|
|
#header>h1:first-child+#toc{margin-top:8px;border-top:1px solid #dddddf}
|
||
|
|
#header>h1:only-child,body.toc2 #header>h1:nth-last-child(2){border-bottom:1px solid #dddddf;padding-bottom:8px}
|
||
|
|
#header .details{border-bottom:1px solid #dddddf;line-height:1.45;padding-top:.25em;padding-bottom:.25em;padding-left:.25em;color:rgba(0,0,0,.6);display:-ms-flexbox;display:-webkit-flex;display:flex;-ms-flex-flow:row wrap;-webkit-flex-flow:row wrap;flex-flow:row wrap}
|
||
|
|
#header .details span:first-child{margin-left:-.125em}
|
||
|
|
#header .details span.email a{color:rgba(0,0,0,.85)}
|
||
|
|
#header .details br{display:none}
|
||
|
|
#header .details br+span::before{content:"\00a0\2013\00a0"}
|
||
|
|
#header .details br+span.author::before{content:"\00a0\22c5\00a0";color:rgba(0,0,0,.85)}
|
||
|
|
#header .details br+span#revremark::before{content:"\00a0|\00a0"}
|
||
|
|
#header #revnumber{text-transform:capitalize}
|
||
|
|
#header #revnumber::after{content:"\00a0"}
|
||
|
|
#content>h1:first-child:not([class]){color:rgba(0,0,0,.85);border-bottom:1px solid #dddddf;padding-bottom:8px;margin-top:0;padding-top:1rem;margin-bottom:1.25rem}
|
||
|
|
#toc{border-bottom:1px solid #e7e7e9;padding-bottom:.5em}
|
||
|
|
#toc>ul{margin-left:.125em}
|
||
|
|
#toc ul.sectlevel0>li>a{font-style:italic}
|
||
|
|
#toc ul.sectlevel0 ul.sectlevel1{margin:.5em 0}
|
||
|
|
#toc ul{font-family:"Open Sans","DejaVu Sans",sans-serif;list-style-type:none}
|
||
|
|
#toc li{line-height:1.3334;margin-top:.3334em}
|
||
|
|
#toc a{text-decoration:none}
|
||
|
|
#toc a:active{text-decoration:underline}
|
||
|
|
#toctitle{color:#7a2518;font-size:1.2em}
|
||
|
|
@media screen and (min-width:768px){#toctitle{font-size:1.375em}
|
||
|
|
body.toc2{padding-left:15em;padding-right:0}
|
||
|
|
#toc.toc2{margin-top:0!important;background:#f8f8f7;position:fixed;width:15em;left:0;top:0;border-right:1px solid #e7e7e9;border-top-width:0!important;border-bottom-width:0!important;z-index:1000;padding:1.25em 1em;height:100%;overflow:auto}
|
||
|
|
#toc.toc2 #toctitle{margin-top:0;margin-bottom:.8rem;font-size:1.2em}
|
||
|
|
#toc.toc2>ul{font-size:.9em;margin-bottom:0}
|
||
|
|
#toc.toc2 ul ul{margin-left:0;padding-left:1em}
|
||
|
|
#toc.toc2 ul.sectlevel0 ul.sectlevel1{padding-left:0;margin-top:.5em;margin-bottom:.5em}
|
||
|
|
body.toc2.toc-right{padding-left:0;padding-right:15em}
|
||
|
|
body.toc2.toc-right #toc.toc2{border-right-width:0;border-left:1px solid #e7e7e9;left:auto;right:0}}
|
||
|
|
@media screen and (min-width:1280px){body.toc2{padding-left:20em;padding-right:0}
|
||
|
|
#toc.toc2{width:20em}
|
||
|
|
#toc.toc2 #toctitle{font-size:1.375em}
|
||
|
|
#toc.toc2>ul{font-size:.95em}
|
||
|
|
#toc.toc2 ul ul{padding-left:1.25em}
|
||
|
|
body.toc2.toc-right{padding-left:0;padding-right:20em}}
|
||
|
|
#content #toc{border-style:solid;border-width:1px;border-color:#e0e0dc;margin-bottom:1.25em;padding:1.25em;background:#f8f8f7;-webkit-border-radius:4px;border-radius:4px}
|
||
|
|
#content #toc>:first-child{margin-top:0}
|
||
|
|
#content #toc>:last-child{margin-bottom:0}
|
||
|
|
#footer{max-width:100%;background:rgba(0,0,0,.8);padding:1.25em}
|
||
|
|
#footer-text{color:rgba(255,255,255,.8);line-height:1.44}
|
||
|
|
#content{margin-bottom:.625em}
|
||
|
|
.sect1{padding-bottom:.625em}
|
||
|
|
@media screen and (min-width:768px){#content{margin-bottom:1.25em}
|
||
|
|
.sect1{padding-bottom:1.25em}}
|
||
|
|
.sect1:last-child{padding-bottom:0}
|
||
|
|
.sect1+.sect1{border-top:1px solid #e7e7e9}
|
||
|
|
#content h1>a.anchor,h2>a.anchor,h3>a.anchor,#toctitle>a.anchor,.sidebarblock>.content>.title>a.anchor,h4>a.anchor,h5>a.anchor,h6>a.anchor{position:absolute;z-index:1001;width:1.5ex;margin-left:-1.5ex;display:block;text-decoration:none!important;visibility:hidden;text-align:center;font-weight:400}
|
||
|
|
#content h1>a.anchor::before,h2>a.anchor::before,h3>a.anchor::before,#toctitle>a.anchor::before,.sidebarblock>.content>.title>a.anchor::before,h4>a.anchor::before,h5>a.anchor::before,h6>a.anchor::before{content:"\00A7";font-size:.85em;display:block;padding-top:.1em}
|
||
|
|
#content h1:hover>a.anchor,#content h1>a.anchor:hover,h2:hover>a.anchor,h2>a.anchor:hover,h3:hover>a.anchor,#toctitle:hover>a.anchor,.sidebarblock>.content>.title:hover>a.anchor,h3>a.anchor:hover,#toctitle>a.anchor:hover,.sidebarblock>.content>.title>a.anchor:hover,h4:hover>a.anchor,h4>a.anchor:hover,h5:hover>a.anchor,h5>a.anchor:hover,h6:hover>a.anchor,h6>a.anchor:hover{visibility:visible}
|
||
|
|
#content h1>a.link,h2>a.link,h3>a.link,#toctitle>a.link,.sidebarblock>.content>.title>a.link,h4>a.link,h5>a.link,h6>a.link{color:#ba3925;text-decoration:none}
|
||
|
|
#content h1>a.link:hover,h2>a.link:hover,h3>a.link:hover,#toctitle>a.link:hover,.sidebarblock>.content>.title>a.link:hover,h4>a.link:hover,h5>a.link:hover,h6>a.link:hover{color:#a53221}
|
||
|
|
details,.audioblock,.imageblock,.literalblock,.listingblock,.stemblock,.videoblock{margin-bottom:1.25em}
|
||
|
|
details>summary:first-of-type{cursor:pointer;display:list-item;outline:none;margin-bottom:.75em}
|
||
|
|
.admonitionblock td.content>.title,.audioblock>.title,.exampleblock>.title,.imageblock>.title,.listingblock>.title,.literalblock>.title,.stemblock>.title,.openblock>.title,.paragraph>.title,.quoteblock>.title,table.tableblock>.title,.verseblock>.title,.videoblock>.title,.dlist>.title,.olist>.title,.ulist>.title,.qlist>.title,.hdlist>.title{text-rendering:optimizeLegibility;text-align:left;font-family:"Noto Serif","DejaVu Serif",serif;font-size:1rem;font-style:italic}
|
||
|
|
table.tableblock.fit-content>caption.title{white-space:nowrap;width:0}
|
||
|
|
.paragraph.lead>p,#preamble>.sectionbody>[class="paragraph"]:first-of-type p{font-size:1.21875em;line-height:1.6;color:rgba(0,0,0,.85)}
|
||
|
|
table.tableblock #preamble>.sectionbody>[class="paragraph"]:first-of-type p{font-size:inherit}
|
||
|
|
.admonitionblock>table{border-collapse:separate;border:0;background:none;width:100%}
|
||
|
|
.admonitionblock>table td.icon{text-align:center;width:80px}
|
||
|
|
.admonitionblock>table td.icon img{max-width:none}
|
||
|
|
.admonitionblock>table td.icon .title{font-weight:bold;font-family:"Open Sans","DejaVu Sans",sans-serif;text-transform:uppercase}
|
||
|
|
.admonitionblock>table td.content{padding-left:1.125em;padding-right:1.25em;border-left:1px solid #dddddf;color:rgba(0,0,0,.6)}
|
||
|
|
.admonitionblock>table td.content>:last-child>:last-child{margin-bottom:0}
|
||
|
|
.exampleblock>.content{border-style:solid;border-width:1px;border-color:#e6e6e6;margin-bottom:1.25em;padding:1.25em;background:#fff;-webkit-border-radius:4px;border-radius:4px}
|
||
|
|
.exampleblock>.content>:first-child{margin-top:0}
|
||
|
|
.exampleblock>.content>:last-child{margin-bottom:0}
|
||
|
|
.sidebarblock{border-style:solid;border-width:1px;border-color:#dbdbd6;margin-bottom:1.25em;padding:1.25em;background:#f3f3f2;-webkit-border-radius:4px;border-radius:4px}
|
||
|
|
.sidebarblock>:first-child{margin-top:0}
|
||
|
|
.sidebarblock>:last-child{margin-bottom:0}
|
||
|
|
.sidebarblock>.content>.title{color:#7a2518;margin-top:0;text-align:center}
|
||
|
|
.exampleblock>.content>:last-child>:last-child,.exampleblock>.content .olist>ol>li:last-child>:last-child,.exampleblock>.content .ulist>ul>li:last-child>:last-child,.exampleblock>.content .qlist>ol>li:last-child>:last-child,.sidebarblock>.content>:last-child>:last-child,.sidebarblock>.content .olist>ol>li:last-child>:last-child,.sidebarblock>.content .ulist>ul>li:last-child>:last-child,.sidebarblock>.content .qlist>ol>li:last-child>:last-child{margin-bottom:0}
|
||
|
|
.literalblock pre,.listingblock>.content>pre{-webkit-border-radius:4px;border-radius:4px;word-wrap:break-word;overflow-x:auto;padding:1em;font-size:.8125em}
|
||
|
|
@media screen and (min-width:768px){.literalblock pre,.listingblock>.content>pre{font-size:.90625em}}
|
||
|
|
@media screen and (min-width:1280px){.literalblock pre,.listingblock>.content>pre{font-size:1em}}
|
||
|
|
.literalblock pre,.listingblock>.content>pre:not(.highlight),.listingblock>.content>pre[class="highlight"],.listingblock>.content>pre[class^="highlight "]{background:#f7f7f8}
|
||
|
|
.literalblock.output pre{color:#f7f7f8;background:rgba(0,0,0,.9)}
|
||
|
|
.listingblock>.content{position:relative}
|
||
|
|
.listingblock code[data-lang]::before{display:none;content:attr(data-lang);position:absolute;font-size:.75em;top:.425rem;right:.5rem;line-height:1;text-transform:uppercase;color:inherit;opacity:.5}
|
||
|
|
.listingblock:hover code[data-lang]::before{display:block}
|
||
|
|
.listingblock.terminal pre .command::before{content:attr(data-prompt);padding-right:.5em;color:inherit;opacity:.5}
|
||
|
|
.listingblock.terminal pre .command:not([data-prompt])::before{content:"$"}
|
||
|
|
.listingblock pre.highlightjs{padding:0}
|
||
|
|
.listingblock pre.highlightjs>code{padding:1em;-webkit-border-radius:4px;border-radius:4px}
|
||
|
|
.listingblock pre.prettyprint{border-width:0}
|
||
|
|
.prettyprint{background:#f7f7f8}
|
||
|
|
pre.prettyprint .linenums{line-height:1.45;margin-left:2em}
|
||
|
|
pre.prettyprint li{background:none;list-style-type:inherit;padding-left:0}
|
||
|
|
pre.prettyprint li code[data-lang]::before{opacity:1}
|
||
|
|
pre.prettyprint li:not(:first-child) code[data-lang]::before{display:none}
|
||
|
|
table.linenotable{border-collapse:separate;border:0;margin-bottom:0;background:none}
|
||
|
|
table.linenotable td[class]{color:inherit;vertical-align:top;padding:0;line-height:inherit;white-space:normal}
|
||
|
|
table.linenotable td.code{padding-left:.75em}
|
||
|
|
table.linenotable td.linenos{border-right:1px solid currentColor;opacity:.35;padding-right:.5em}
|
||
|
|
pre.pygments .lineno{border-right:1px solid currentColor;opacity:.35;display:inline-block;margin-right:.75em}
|
||
|
|
pre.pygments .lineno::before{content:"";margin-right:-.125em}
|
||
|
|
.quoteblock{margin:0 1em 1.25em 1.5em;display:table}
|
||
|
|
.quoteblock:not(.excerpt)>.title{margin-left:-1.5em;margin-bottom:.75em}
|
||
|
|
.quoteblock blockquote,.quoteblock p{color:rgba(0,0,0,.85);font-size:1.15rem;line-height:1.75;word-spacing:.1em;letter-spacing:0;font-style:italic;text-align:justify}
|
||
|
|
.quoteblock blockquote{margin:0;padding:0;border:0}
|
||
|
|
.quoteblock blockquote::before{content:"\201c";float:left;font-size:2.75em;font-weight:bold;line-height:.6em;margin-left:-.6em;color:#7a2518;text-shadow:0 1px 2px rgba(0,0,0,.1)}
|
||
|
|
.quoteblock blockquote>.paragraph:last-child p{margin-bottom:0}
|
||
|
|
.quoteblock .attribution{margin-top:.75em;margin-right:.5ex;text-align:right}
|
||
|
|
.verseblock{margin:0 1em 1.25em}
|
||
|
|
.verseblock pre{font-family:"Open Sans","DejaVu Sans",sans;font-size:1.15rem;color:rgba(0,0,0,.85);font-weight:300;text-rendering:optimizeLegibility}
|
||
|
|
.verseblock pre strong{font-weight:400}
|
||
|
|
.verseblock .attribution{margin-top:1.25rem;margin-left:.5ex}
|
||
|
|
.quoteblock .attribution,.verseblock .attribution{font-size:.9375em;line-height:1.45;font-style:italic}
|
||
|
|
.quoteblock .attribution br,.verseblock .attribution br{display:none}
|
||
|
|
.quoteblock .attribution cite,.verseblock .attribution cite{display:block;letter-spacing:-.025em;color:rgba(0,0,0,.6)}
|
||
|
|
.quoteblock.abstract blockquote::before,.quoteblock.excerpt blockquote::before,.quoteblock .quoteblock blockquote::before{display:none}
|
||
|
|
.quoteblock.abstract blockquote,.quoteblock.abstract p,.quoteblock.excerpt blockquote,.quoteblock.excerpt p,.quoteblock .quoteblock blockquote,.quoteblock .quoteblock p{line-height:1.6;word-spacing:0}
|
||
|
|
.quoteblock.abstract{margin:0 1em 1.25em;display:block}
|
||
|
|
.quoteblock.abstract>.title{margin:0 0 .375em;font-size:1.15em;text-align:center}
|
||
|
|
.quoteblock.excerpt>blockquote,.quoteblock .quoteblock{padding:0 0 .25em 1em;border-left:.25em solid #dddddf}
|
||
|
|
.quoteblock.excerpt,.quoteblock .quoteblock{margin-left:0}
|
||
|
|
.quoteblock.excerpt blockquote,.quoteblock.excerpt p,.quoteblock .quoteblock blockquote,.quoteblock .quoteblock p{color:inherit;font-size:1.0625rem}
|
||
|
|
.quoteblock.excerpt .attribution,.quoteblock .quoteblock .attribution{color:inherit;text-align:left;margin-right:0}
|
||
|
|
table.tableblock{max-width:100%;border-collapse:separate}
|
||
|
|
p.tableblock:last-child{margin-bottom:0}
|
||
|
|
td.tableblock>.content>:last-child{margin-bottom:-1.25em}
|
||
|
|
td.tableblock>.content>:last-child.sidebarblock{margin-bottom:0}
|
||
|
|
table.tableblock,th.tableblock,td.tableblock{border:0 solid #dedede}
|
||
|
|
table.grid-all>thead>tr>.tableblock,table.grid-all>tbody>tr>.tableblock{border-width:0 1px 1px 0}
|
||
|
|
table.grid-all>tfoot>tr>.tableblock{border-width:1px 1px 0 0}
|
||
|
|
table.grid-cols>*>tr>.tableblock{border-width:0 1px 0 0}
|
||
|
|
table.grid-rows>thead>tr>.tableblock,table.grid-rows>tbody>tr>.tableblock{border-width:0 0 1px}
|
||
|
|
table.grid-rows>tfoot>tr>.tableblock{border-width:1px 0 0}
|
||
|
|
table.grid-all>*>tr>.tableblock:last-child,table.grid-cols>*>tr>.tableblock:last-child{border-right-width:0}
|
||
|
|
table.grid-all>tbody>tr:last-child>.tableblock,table.grid-all>thead:last-child>tr>.tableblock,table.grid-rows>tbody>tr:last-child>.tableblock,table.grid-rows>thead:last-child>tr>.tableblock{border-bottom-width:0}
|
||
|
|
table.frame-all{border-width:1px}
|
||
|
|
table.frame-sides{border-width:0 1px}
|
||
|
|
table.frame-topbot,table.frame-ends{border-width:1px 0}
|
||
|
|
table.stripes-all tr,table.stripes-odd tr:nth-of-type(odd),table.stripes-even tr:nth-of-type(even),table.stripes-hover tr:hover{background:#f8f8f7}
|
||
|
|
th.halign-left,td.halign-left{text-align:left}
|
||
|
|
th.halign-right,td.halign-right{text-align:right}
|
||
|
|
th.halign-center,td.halign-center{text-align:center}
|
||
|
|
th.valign-top,td.valign-top{vertical-align:top}
|
||
|
|
th.valign-bottom,td.valign-bottom{vertical-align:bottom}
|
||
|
|
th.valign-middle,td.valign-middle{vertical-align:middle}
|
||
|
|
table thead th,table tfoot th{font-weight:bold}
|
||
|
|
tbody tr th{display:table-cell;line-height:1.6;background:#f7f8f7}
|
||
|
|
tbody tr th,tbody tr th p,tfoot tr th,tfoot tr th p{color:rgba(0,0,0,.8);font-weight:bold}
|
||
|
|
p.tableblock>code:only-child{background:none;padding:0}
|
||
|
|
p.tableblock{font-size:1em}
|
||
|
|
ol{margin-left:1.75em}
|
||
|
|
ul li ol{margin-left:1.5em}
|
||
|
|
dl dd{margin-left:1.125em}
|
||
|
|
dl dd:last-child,dl dd:last-child>:last-child{margin-bottom:0}
|
||
|
|
ol>li p,ul>li p,ul dd,ol dd,.olist .olist,.ulist .ulist,.ulist .olist,.olist .ulist{margin-bottom:.625em}
|
||
|
|
ul.checklist,ul.none,ol.none,ul.no-bullet,ol.no-bullet,ol.unnumbered,ul.unstyled,ol.unstyled{list-style-type:none}
|
||
|
|
ul.no-bullet,ol.no-bullet,ol.unnumbered{margin-left:.625em}
|
||
|
|
ul.unstyled,ol.unstyled{margin-left:0}
|
||
|
|
ul.checklist{margin-left:.625em}
|
||
|
|
ul.checklist li>p:first-child>.fa-square-o:first-child,ul.checklist li>p:first-child>.fa-check-square-o:first-child{width:1.25em;font-size:.8em;position:relative;bottom:.125em}
|
||
|
|
ul.checklist li>p:first-child>input[type="checkbox"]:first-child{margin-right:.25em}
|
||
|
|
ul.inline{display:-ms-flexbox;display:-webkit-box;display:flex;-ms-flex-flow:row wrap;-webkit-flex-flow:row wrap;flex-flow:row wrap;list-style:none;margin:0 0 .625em -1.25em}
|
||
|
|
ul.inline>li{margin-left:1.25em}
|
||
|
|
.unstyled dl dt{font-weight:400;font-style:normal}
|
||
|
|
ol.arabic{list-style-type:decimal}
|
||
|
|
ol.decimal{list-style-type:decimal-leading-zero}
|
||
|
|
ol.loweralpha{list-style-type:lower-alpha}
|
||
|
|
ol.upperalpha{list-style-type:upper-alpha}
|
||
|
|
ol.lowerroman{list-style-type:lower-roman}
|
||
|
|
ol.upperroman{list-style-type:upper-roman}
|
||
|
|
ol.lowergreek{list-style-type:lower-greek}
|
||
|
|
.hdlist>table,.colist>table{border:0;background:none}
|
||
|
|
.hdlist>table>tbody>tr,.colist>table>tbody>tr{background:none}
|
||
|
|
td.hdlist1,td.hdlist2{vertical-align:top;padding:0 .625em}
|
||
|
|
td.hdlist1{font-weight:bold;padding-bottom:1.25em}
|
||
|
|
.literalblock+.colist,.listingblock+.colist{margin-top:-.5em}
|
||
|
|
.colist td:not([class]):first-child{padding:.4em .75em 0;line-height:1;vertical-align:top}
|
||
|
|
.colist td:not([class]):first-child img{max-width:none}
|
||
|
|
.colist td:not([class]):last-child{padding:.25em 0}
|
||
|
|
.thumb,.th{line-height:0;display:inline-block;border:solid 4px #fff;-webkit-box-shadow:0 0 0 1px #ddd;box-shadow:0 0 0 1px #ddd}
|
||
|
|
.imageblock.left{margin:.25em .625em 1.25em 0}
|
||
|
|
.imageblock.right{margin:.25em 0 1.25em .625em}
|
||
|
|
.imageblock>.title{margin-bottom:0}
|
||
|
|
.imageblock.thumb,.imageblock.th{border-width:6px}
|
||
|
|
.imageblock.thumb>.title,.imageblock.th>.title{padding:0 .125em}
|
||
|
|
.image.left,.image.right{margin-top:.25em;margin-bottom:.25em;display:inline-block;line-height:0}
|
||
|
|
.image.left{margin-right:.625em}
|
||
|
|
.image.right{margin-left:.625em}
|
||
|
|
a.image{text-decoration:none;display:inline-block}
|
||
|
|
a.image object{pointer-events:none}
|
||
|
|
sup.footnote,sup.footnoteref{font-size:.875em;position:static;vertical-align:super}
|
||
|
|
sup.footnote a,sup.footnoteref a{text-decoration:none}
|
||
|
|
sup.footnote a:active,sup.footnoteref a:active{text-decoration:underline}
|
||
|
|
#footnotes{padding-top:.75em;padding-bottom:.75em;margin-bottom:.625em}
|
||
|
|
#footnotes hr{width:20%;min-width:6.25em;margin:-.25em 0 .75em;border-width:1px 0 0}
|
||
|
|
#footnotes .footnote{padding:0 .375em 0 .225em;line-height:1.3334;font-size:.875em;margin-left:1.2em;margin-bottom:.2em}
|
||
|
|
#footnotes .footnote a:first-of-type{font-weight:bold;text-decoration:none;margin-left:-1.05em}
|
||
|
|
#footnotes .footnote:last-of-type{margin-bottom:0}
|
||
|
|
#content #footnotes{margin-top:-.625em;margin-bottom:0;padding:.75em 0}
|
||
|
|
.gist .file-data>table{border:0;background:#fff;width:100%;margin-bottom:0}
|
||
|
|
.gist .file-data>table td.line-data{width:99%}
|
||
|
|
div.unbreakable{page-break-inside:avoid}
|
||
|
|
.big{font-size:larger}
|
||
|
|
.small{font-size:smaller}
|
||
|
|
.underline{text-decoration:underline}
|
||
|
|
.overline{text-decoration:overline}
|
||
|
|
.line-through{text-decoration:line-through}
|
||
|
|
.aqua{color:#00bfbf}
|
||
|
|
.aqua-background{background:#00fafa}
|
||
|
|
.black{color:#000}
|
||
|
|
.black-background{background:#000}
|
||
|
|
.blue{color:#0000bf}
|
||
|
|
.blue-background{background:#0000fa}
|
||
|
|
.fuchsia{color:#bf00bf}
|
||
|
|
.fuchsia-background{background:#fa00fa}
|
||
|
|
.gray{color:#606060}
|
||
|
|
.gray-background{background:#7d7d7d}
|
||
|
|
.green{color:#006000}
|
||
|
|
.green-background{background:#007d00}
|
||
|
|
.lime{color:#00bf00}
|
||
|
|
.lime-background{background:#00fa00}
|
||
|
|
.maroon{color:#600000}
|
||
|
|
.maroon-background{background:#7d0000}
|
||
|
|
.navy{color:#000060}
|
||
|
|
.navy-background{background:#00007d}
|
||
|
|
.olive{color:#606000}
|
||
|
|
.olive-background{background:#7d7d00}
|
||
|
|
.purple{color:#600060}
|
||
|
|
.purple-background{background:#7d007d}
|
||
|
|
.red{color:#bf0000}
|
||
|
|
.red-background{background:#fa0000}
|
||
|
|
.silver{color:#909090}
|
||
|
|
.silver-background{background:#bcbcbc}
|
||
|
|
.teal{color:#006060}
|
||
|
|
.teal-background{background:#007d7d}
|
||
|
|
.white{color:#bfbfbf}
|
||
|
|
.white-background{background:#fafafa}
|
||
|
|
.yellow{color:#bfbf00}
|
||
|
|
.yellow-background{background:#fafa00}
|
||
|
|
span.icon>.fa{cursor:default}
|
||
|
|
a span.icon>.fa{cursor:inherit}
|
||
|
|
.admonitionblock td.icon [class^="fa icon-"]{font-size:2.5em;text-shadow:1px 1px 2px rgba(0,0,0,.5);cursor:default}
|
||
|
|
.admonitionblock td.icon .icon-note::before{content:"\f05a";color:#19407c}
|
||
|
|
.admonitionblock td.icon .icon-tip::before{content:"\f0eb";text-shadow:1px 1px 2px rgba(155,155,0,.8);color:#111}
|
||
|
|
.admonitionblock td.icon .icon-warning::before{content:"\f071";color:#bf6900}
|
||
|
|
.admonitionblock td.icon .icon-caution::before{content:"\f06d";color:#bf3400}
|
||
|
|
.admonitionblock td.icon .icon-important::before{content:"\f06a";color:#bf0000}
|
||
|
|
.conum[data-value]{display:inline-block;color:#fff!important;background:rgba(0,0,0,.8);-webkit-border-radius:100px;border-radius:100px;text-align:center;font-size:.75em;width:1.67em;height:1.67em;line-height:1.67em;font-family:"Open Sans","DejaVu Sans",sans-serif;font-style:normal;font-weight:bold}
|
||
|
|
.conum[data-value] *{color:#fff!important}
|
||
|
|
.conum[data-value]+b{display:none}
|
||
|
|
.conum[data-value]::after{content:attr(data-value)}
|
||
|
|
pre .conum[data-value]{position:relative;top:-.125em}
|
||
|
|
b.conum *{color:inherit!important}
|
||
|
|
.conum:not([data-value]):empty{display:none}
|
||
|
|
dt,th.tableblock,td.content,div.footnote{text-rendering:optimizeLegibility}
|
||
|
|
h1,h2,p,td.content,span.alt{letter-spacing:-.01em}
|
||
|
|
p strong,td.content strong,div.footnote strong{letter-spacing:-.005em}
|
||
|
|
p,blockquote,dt,td.content,span.alt{font-size:1.0625rem}
|
||
|
|
p{margin-bottom:1.25rem}
|
||
|
|
.sidebarblock p,.sidebarblock dt,.sidebarblock td.content,p.tableblock{font-size:1em}
|
||
|
|
.exampleblock>.content{background:#fffef7;border-color:#e0e0dc;-webkit-box-shadow:0 1px 4px #e0e0dc;box-shadow:0 1px 4px #e0e0dc}
|
||
|
|
.print-only{display:none!important}
|
||
|
|
@page{margin:1.25cm .75cm}
|
||
|
|
@media print{*{-webkit-box-shadow:none!important;box-shadow:none!important;text-shadow:none!important}
|
||
|
|
html{font-size:80%}
|
||
|
|
a{color:inherit!important;text-decoration:underline!important}
|
||
|
|
a.bare,a[href^="#"],a[href^="mailto:"]{text-decoration:none!important}
|
||
|
|
a[href^="http:"]:not(.bare)::after,a[href^="https:"]:not(.bare)::after{content:"(" attr(href) ")";display:inline-block;font-size:.875em;padding-left:.25em}
|
||
|
|
abbr[title]::after{content:" (" attr(title) ")"}
|
||
|
|
pre,blockquote,tr,img,object,svg{page-break-inside:avoid}
|
||
|
|
thead{display:table-header-group}
|
||
|
|
svg{max-width:100%}
|
||
|
|
p,blockquote,dt,td.content{font-size:1em;orphans:3;widows:3}
|
||
|
|
h2,h3,#toctitle,.sidebarblock>.content>.title{page-break-after:avoid}
|
||
|
|
#toc,.sidebarblock,.exampleblock>.content{background:none!important}
|
||
|
|
#toc{border-bottom:1px solid #dddddf!important;padding-bottom:0!important}
|
||
|
|
body.book #header{text-align:center}
|
||
|
|
body.book #header>h1:first-child{border:0!important;margin:2.5em 0 1em}
|
||
|
|
body.book #header .details{border:0!important;display:block;padding:0!important}
|
||
|
|
body.book #header .details span:first-child{margin-left:0!important}
|
||
|
|
body.book #header .details br{display:block}
|
||
|
|
body.book #header .details br+span::before{content:none!important}
|
||
|
|
body.book #toc{border:0!important;text-align:left!important;padding:0!important;margin:0!important}
|
||
|
|
body.book #toc,body.book #preamble,body.book h1.sect0,body.book .sect1>h2{page-break-before:always}
|
||
|
|
.listingblock code[data-lang]::before{display:block}
|
||
|
|
#footer{padding:0 .9375em}
|
||
|
|
.hide-on-print{display:none!important}
|
||
|
|
.print-only{display:block!important}
|
||
|
|
.hide-for-print{display:none!important}
|
||
|
|
.show-for-print{display:inherit!important}}
|
||
|
|
@media print,amzn-kf8{#header>h1:first-child{margin-top:1.25rem}
|
||
|
|
.sect1{padding:0!important}
|
||
|
|
.sect1+.sect1{border:0}
|
||
|
|
#footer{background:none}
|
||
|
|
#footer-text{color:rgba(0,0,0,.6);font-size:.9em}}
|
||
|
|
@media amzn-kf8{#header,#content,#footnotes,#footer{padding:0}}
|
||
|
|
</style>
|
||
|
|
<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/4.7.0/css/font-awesome.min.css">
|
||
|
|
</head>
|
||
|
|
<body class="article toc2 toc-right">
|
||
|
|
<div id="header">
|
||
|
|
<h1>Iptables - Traversing of tables and chains!</h1>
|
||
|
|
<div class="details">
|
||
|
|
<span id="author" class="author">Apostolos rootApostolos@swarmlab.io</span><br>
|
||
|
|
</div>
|
||
|
|
<div id="toc" class="toc2">
|
||
|
|
<div id="toctitle">Table of Contents</div>
|
||
|
|
<ul class="sectlevel1">
|
||
|
|
<li><a href="#_general">1. General</a></li>
|
||
|
|
<li><a href="#_destination_local_host_our_own_machine">2. Destination local host (our own machine)</a></li>
|
||
|
|
<li><a href="#_source_local_host_our_own_machine">3. Source local host (our own machine)</a></li>
|
||
|
|
<li><a href="#_forwarded_packets">4. Forwarded packets</a></li>
|
||
|
|
</ul>
|
||
|
|
</div>
|
||
|
|
</div>
|
||
|
|
<div id="content">
|
||
|
|
<div id="preamble">
|
||
|
|
<div class="sectionbody">
|
||
|
|
<div class="paragraph">
|
||
|
|
<p><br></p>
|
||
|
|
</div>
|
||
|
|
</div>
|
||
|
|
</div>
|
||
|
|
<div class="sect1">
|
||
|
|
<h2 id="_general">1. General</h2>
|
||
|
|
<div class="sectionbody">
|
||
|
|
<div class="paragraph">
|
||
|
|
<p>When a packet first enters the firewall, it hits the hardware and then gets passed on to the proper device driver in the kernel.</p>
|
||
|
|
</div>
|
||
|
|
<div class="paragraph">
|
||
|
|
<p>Then the packet starts to go through a series of steps in the kernel, before it is either sent to the correct application (locally), or forwarded to another host - or whatever happens to it.</p>
|
||
|
|
</div>
|
||
|
|
</div>
|
||
|
|
</div>
|
||
|
|
<div class="sect1">
|
||
|
|
<h2 id="_destination_local_host_our_own_machine">2. Destination local host (our own machine)</h2>
|
||
|
|
<div class="sectionbody">
|
||
|
|
<table class="tableblock frame-all grid-all stretch">
|
||
|
|
<caption class="title">Table 1. Destination local host</caption>
|
||
|
|
<colgroup>
|
||
|
|
<col style="width: 25%;">
|
||
|
|
<col style="width: 25%;">
|
||
|
|
<col style="width: 25%;">
|
||
|
|
<col style="width: 25%;">
|
||
|
|
</colgroup>
|
||
|
|
<tbody>
|
||
|
|
<tr>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">Step</p></td>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">Table</p></td>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">Chain</p></td>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">Comment</p></td>
|
||
|
|
</tr>
|
||
|
|
<tr>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">1</p></td>
|
||
|
|
<td class="tableblock halign-left valign-top"></td>
|
||
|
|
<td class="tableblock halign-left valign-top"></td>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">On the wire (e.g., Internet)</p></td>
|
||
|
|
</tr>
|
||
|
|
<tr>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">2</p></td>
|
||
|
|
<td class="tableblock halign-left valign-top"></td>
|
||
|
|
<td class="tableblock halign-left valign-top"></td>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">Comes in on the interface (e.g., eth0)</p></td>
|
||
|
|
</tr>
|
||
|
|
<tr>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">3</p></td>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">raw</p></td>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">PREROUTING</p></td>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">This chain is used to handle packets before the connection tracking takes place. It can be used to set a specific connection not to be handled by the connection tracking code for example.</p></td>
|
||
|
|
</tr>
|
||
|
|
<tr>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">4</p></td>
|
||
|
|
<td class="tableblock halign-left valign-top"></td>
|
||
|
|
<td class="tableblock halign-left valign-top"></td>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">This is when the connection tracking code takes place</p></td>
|
||
|
|
</tr>
|
||
|
|
<tr>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">5</p></td>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">mangle</p></td>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">PREROUTING</p></td>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">This chain is normally used for mangling packets, i.e., changing TOS and so on.</p></td>
|
||
|
|
</tr>
|
||
|
|
<tr>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">6</p></td>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">nat</p></td>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">PREROUTING</p></td>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">This chain is used for DNAT mainly. Avoid filtering in this chain since it will be bypassed in certain cases.</p></td>
|
||
|
|
</tr>
|
||
|
|
<tr>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">7</p></td>
|
||
|
|
<td class="tableblock halign-left valign-top"></td>
|
||
|
|
<td class="tableblock halign-left valign-top"></td>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">Routing decision, i.e., is the packet destined for our local host or to be forwarded and where.</p></td>
|
||
|
|
</tr>
|
||
|
|
<tr>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">8</p></td>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">mangle</p></td>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">INPUT</p></td>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">At this point, the mangle INPUT chain is hit. We use this chain to mangle packets, after they have been routed, but before they are actually sent to the process on the machine.</p></td>
|
||
|
|
</tr>
|
||
|
|
<tr>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">9</p></td>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">filter</p></td>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">INPUT</p></td>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">This is where we do filtering for all incoming traffic destined for our local host. Note that all incoming packets destined for this host pass through this chain, no matter what interface or in which direction they came from.</p></td>
|
||
|
|
</tr>
|
||
|
|
<tr>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">10</p></td>
|
||
|
|
<td class="tableblock halign-left valign-top"></td>
|
||
|
|
<td class="tableblock halign-left valign-top"></td>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">Local process or application (i.e., server or client program).</p></td>
|
||
|
|
</tr>
|
||
|
|
</tbody>
|
||
|
|
</table>
|
||
|
|
</div>
|
||
|
|
</div>
|
||
|
|
<div class="sect1">
|
||
|
|
<h2 id="_source_local_host_our_own_machine">3. Source local host (our own machine)</h2>
|
||
|
|
<div class="sectionbody">
|
||
|
|
<table class="tableblock frame-all grid-all stretch">
|
||
|
|
<caption class="title">Table 2. Source local host</caption>
|
||
|
|
<colgroup>
|
||
|
|
<col style="width: 25%;">
|
||
|
|
<col style="width: 25%;">
|
||
|
|
<col style="width: 25%;">
|
||
|
|
<col style="width: 25%;">
|
||
|
|
</colgroup>
|
||
|
|
<tbody>
|
||
|
|
<tr>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">Step</p></td>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">Table</p></td>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">Chain</p></td>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">Comment</p></td>
|
||
|
|
</tr>
|
||
|
|
<tr>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">1</p></td>
|
||
|
|
<td class="tableblock halign-left valign-top"></td>
|
||
|
|
<td class="tableblock halign-left valign-top"></td>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">Local process/application (i.e., server/client program)</p></td>
|
||
|
|
</tr>
|
||
|
|
<tr>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">2</p></td>
|
||
|
|
<td class="tableblock halign-left valign-top"></td>
|
||
|
|
<td class="tableblock halign-left valign-top"></td>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">Routing decision. What source address to use, what outgoing interface to use, and other necessary information that needs to be gathered.</p></td>
|
||
|
|
</tr>
|
||
|
|
<tr>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">3</p></td>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">raw</p></td>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">OUTPUT</p></td>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">This is where you do work before the connection tracking has taken place for locally generated packets. You can mark connections so that they will not be tracked for example.</p></td>
|
||
|
|
</tr>
|
||
|
|
<tr>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">4</p></td>
|
||
|
|
<td class="tableblock halign-left valign-top"></td>
|
||
|
|
<td class="tableblock halign-left valign-top"></td>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">This is where the connection tracking takes place for locally generated packets, for example state changes et cetera.</p></td>
|
||
|
|
</tr>
|
||
|
|
<tr>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">5</p></td>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">mangle</p></td>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">OUTPUT</p></td>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">This is where we mangle packets, it is suggested that you do not filter in this chain since it can have side effects.</p></td>
|
||
|
|
</tr>
|
||
|
|
<tr>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">6</p></td>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">nat</p></td>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">OUTPUT</p></td>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">This chain can be used to NAT outgoing packets from the firewall itself.</p></td>
|
||
|
|
</tr>
|
||
|
|
<tr>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">7</p></td>
|
||
|
|
<td class="tableblock halign-left valign-top"></td>
|
||
|
|
<td class="tableblock halign-left valign-top"></td>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">Routing decision, since the previous mangle and nat changes may have changed how the packet should be routed.</p></td>
|
||
|
|
</tr>
|
||
|
|
<tr>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">8</p></td>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">filter</p></td>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">OUTPUT</p></td>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">This is where we filter packets going out from the local host.</p></td>
|
||
|
|
</tr>
|
||
|
|
<tr>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">9</p></td>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">mangle</p></td>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">POSTROUTING</p></td>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">The POSTROUTING chain in the mangle table is mainly used when we want to do mangling on packets before they leave our host, but after the actual routing decisions. This chain will be hit by both packets just traversing the firewall, as well as packets created by the firewall itself.</p></td>
|
||
|
|
</tr>
|
||
|
|
<tr>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">10</p></td>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">nat</p></td>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">POSTROUTING</p></td>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">This is where we do SNAT as described earlier. It is suggested that you don’t do filtering here since it can have side effects, and certain packets might slip through even though you set a default policy of DROP.</p></td>
|
||
|
|
</tr>
|
||
|
|
<tr>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">11</p></td>
|
||
|
|
<td class="tableblock halign-left valign-top"></td>
|
||
|
|
<td class="tableblock halign-left valign-top"></td>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">Goes out on some interface (e.g., eth0)</p></td>
|
||
|
|
</tr>
|
||
|
|
<tr>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">12</p></td>
|
||
|
|
<td class="tableblock halign-left valign-top"></td>
|
||
|
|
<td class="tableblock halign-left valign-top"></td>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">On the wire (e.g., Internet)</p></td>
|
||
|
|
</tr>
|
||
|
|
</tbody>
|
||
|
|
</table>
|
||
|
|
</div>
|
||
|
|
</div>
|
||
|
|
<div class="sect1">
|
||
|
|
<h2 id="_forwarded_packets">4. Forwarded packets</h2>
|
||
|
|
<div class="sectionbody">
|
||
|
|
<div class="paragraph">
|
||
|
|
<p>In this example, we’re assuming that the packet is destined for another host on another network. The packet goes through the different steps in the following fashion:</p>
|
||
|
|
</div>
|
||
|
|
<table class="tableblock frame-all grid-all stretch">
|
||
|
|
<caption class="title">Table 3. Forwarded packets</caption>
|
||
|
|
<colgroup>
|
||
|
|
<col style="width: 25%;">
|
||
|
|
<col style="width: 25%;">
|
||
|
|
<col style="width: 25%;">
|
||
|
|
<col style="width: 25%;">
|
||
|
|
</colgroup>
|
||
|
|
<tbody>
|
||
|
|
<tr>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">Step</p></td>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">Table</p></td>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">Chain</p></td>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">Comment</p></td>
|
||
|
|
</tr>
|
||
|
|
<tr>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">1</p></td>
|
||
|
|
<td class="tableblock halign-left valign-top"></td>
|
||
|
|
<td class="tableblock halign-left valign-top"></td>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">On the wire (i.e., Internet)</p></td>
|
||
|
|
</tr>
|
||
|
|
<tr>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">2</p></td>
|
||
|
|
<td class="tableblock halign-left valign-top"></td>
|
||
|
|
<td class="tableblock halign-left valign-top"></td>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">Comes in on the interface (i.e., eth0)</p></td>
|
||
|
|
</tr>
|
||
|
|
<tr>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">3</p></td>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">raw</p></td>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">PREROUTING</p></td>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">Here you can set a connection to not be handled by the connection tracking system.</p></td>
|
||
|
|
</tr>
|
||
|
|
<tr>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">4</p></td>
|
||
|
|
<td class="tableblock halign-left valign-top"></td>
|
||
|
|
<td class="tableblock halign-left valign-top"></td>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">This is where the non-locally generated connection tracking takes place.</p></td>
|
||
|
|
</tr>
|
||
|
|
<tr>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">5</p></td>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">mangle</p></td>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">PREROUTING</p></td>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">This chain is normally used for mangling packets, i.e., changing TOS and so on.</p></td>
|
||
|
|
</tr>
|
||
|
|
<tr>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">6</p></td>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">nat</p></td>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">PREROUTING</p></td>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">This chain is used for DNAT mainly. SNAT is done further on. Avoid filtering in this chain since it will be bypassed in certain cases.</p></td>
|
||
|
|
</tr>
|
||
|
|
<tr>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">7</p></td>
|
||
|
|
<td class="tableblock halign-left valign-top"></td>
|
||
|
|
<td class="tableblock halign-left valign-top"></td>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">Routing decision, i.e., is the packet destined for our local host or to be forwarded and where.</p></td>
|
||
|
|
</tr>
|
||
|
|
<tr>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">8</p></td>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">mangle</p></td>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">FORWARD</p></td>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">The packet is then sent on to the FORWARD chain of the mangle table. This can be used for very specific needs, where we want to mangle the packets after the initial routing decision, but before the last routing decision made just before the packet is sent out.</p></td>
|
||
|
|
</tr>
|
||
|
|
<tr>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">9</p></td>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">filter</p></td>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">FORWARD</p></td>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">The packet gets routed onto the FORWARD chain. Only forwarded packets go through here, and here we do all the filtering. Note that all traffic that’s forwarded goes through here (not only in one direction), so you need to think about it when writing your rule-set.</p></td>
|
||
|
|
</tr>
|
||
|
|
<tr>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">10</p></td>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">mangle</p></td>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">POSTROUTING</p></td>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">This chain is used for specific types of packet mangling that we wish to take place after all kinds of routing decisions have been done, but still on this machine.</p></td>
|
||
|
|
</tr>
|
||
|
|
<tr>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">11</p></td>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">nat</p></td>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">POSTROUTING</p></td>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">This chain should first and foremost be used for SNAT. Avoid doing filtering here, since certain packets might pass this chain without ever hitting it. This is also where Masquerading is done.</p></td>
|
||
|
|
</tr>
|
||
|
|
<tr>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">12</p></td>
|
||
|
|
<td class="tableblock halign-left valign-top"></td>
|
||
|
|
<td class="tableblock halign-left valign-top"></td>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">Goes out on the outgoing interface (i.e., eth1).</p></td>
|
||
|
|
</tr>
|
||
|
|
<tr>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">13</p></td>
|
||
|
|
<td class="tableblock halign-left valign-top"></td>
|
||
|
|
<td class="tableblock halign-left valign-top"></td>
|
||
|
|
<td class="tableblock halign-left valign-top"><p class="tableblock">Out on the wire again (i.e., LAN).</p></td>
|
||
|
|
</tr>
|
||
|
|
</tbody>
|
||
|
|
</table>
|
||
|
|
<div class="paragraph">
|
||
|
|
<p><br>
|
||
|
|
<br>
|
||
|
|
</p>
|
||
|
|
</div>
|
||
|
|
<hr>
|
||
|
|
</div>
|
||
|
|
</div>
|
||
|
|
</div>
|
||
|
|
<div id="footer">
|
||
|
|
<div id="footer-text">
|
||
|
|
Last updated 2020-07-09 15:06:15 UTC
|
||
|
|
</div>
|
||
|
|
</div>
|
||
|
|
</body>
|
||
|
|
</html>
|