sahin/sahinakkaya.dev
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

jekyll build from Action 8238e12f4b

Browse Source
This commit is contained in:
Asocia 2022-02-27 14:57:41 +00:00
parent a6ef280026
commit 777df41cd7
10 changed files with 975 additions and 239 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

95
2021/12/24/first-blog-post.html
View File

@ -402,6 +402,53 @@ So here I am and welcome to my first blog. Having a personal space on the Intern
<div class="grid__item">
<article class="archive__item" itemscope itemtype="https://schema.org/CreativeWork">
<h2 class="archive__item-title no_toc" itemprop="headline">
<a href="/2022/02/27/creating-a-useless-user.html" rel="permalink">Creating a <em>Useless</em> User
</a>
</h2>
<p class="page__meta">
<span class="page__meta-date">
<i class="far fa-fw fa-calendar-alt" aria-hidden="true"></i>
<time datetime="2022-02-27T13:40:00+00:00">February 27, 2022</time>
</span>
<span class="page__meta-sep"></span>
<span class="page__meta-readtime">
<i class="far fa-fw fa-clock" aria-hidden="true"></i>
1 minute read
</span>
</p>
<p class="archive__item-excerpt" itemprop="description">Story
In my previous post, I explained how to do port forwarding to access some machine behind private network. I will use this method to fix some issues in ...</p>
</article>
</div>
<div class="grid__item"> <div class="grid__item">
<article class="archive__item" itemscope itemtype="https://schema.org/CreativeWork"> <article class="archive__item" itemscope itemtype="https://schema.org/CreativeWork">
@ -538,54 +585,6 @@ Today, I have recorded a video for one of my classes and I was required to uploa
</div> </div>
<div class="grid__item">
<article class="archive__item" itemscope itemtype="https://schema.org/CreativeWork">
<h2 class="archive__item-title no_toc" itemprop="headline">
<a href="/2022/01/01/stop-cat-pipeing.html" rel="permalink">Stop cat-pipe’ing, You Are Doing It Wrong!
</a>
</h2>
<p class="page__meta">
<span class="page__meta-date">
<i class="far fa-fw fa-calendar-alt" aria-hidden="true"></i>
<time datetime="2022-01-01T15:00:00+00:00">January 1, 2022</time>
</span>
<span class="page__meta-sep"></span>
<span class="page__meta-readtime">
<i class="far fa-fw fa-clock" aria-hidden="true"></i>
2 minute read
</span>
</p>
<p class="archive__item-excerpt" itemprop="description">cat some_file | grep some_pattern
I’m sure that you run a command something like above at least once if you are using terminal. You know how cat and grep wo...</p>
</article>
</div>
</div> </div>
</div> </div>

94
2022/01/01/stop-cat-pipeing.html
View File

@ -430,6 +430,53 @@ util.lua: highlight<span class="o">(</span>group, properties<span class="o">)
<div class="grid__item">
<article class="archive__item" itemscope itemtype="https://schema.org/CreativeWork">
<h2 class="archive__item-title no_toc" itemprop="headline">
<a href="/2022/02/27/creating-a-useless-user.html" rel="permalink">Creating a <em>Useless</em> User
</a>
</h2>
<p class="page__meta">
<span class="page__meta-date">
<i class="far fa-fw fa-calendar-alt" aria-hidden="true"></i>
<time datetime="2022-02-27T13:40:00+00:00">February 27, 2022</time>
</span>
<span class="page__meta-sep"></span>
<span class="page__meta-readtime">
<i class="far fa-fw fa-clock" aria-hidden="true"></i>
1 minute read
</span>
</p>
<p class="archive__item-excerpt" itemprop="description">Story
In my previous post, I explained how to do port forwarding to access some machine behind private network. I will use this method to fix some issues in ...</p>
</article>
</div>
<div class="grid__item"> <div class="grid__item">
<article class="archive__item" itemscope itemtype="https://schema.org/CreativeWork"> <article class="archive__item" itemscope itemtype="https://schema.org/CreativeWork">
@ -566,53 +613,6 @@ Today, I have recorded a video for one of my classes and I was required to uploa
</div> </div>
<div class="grid__item">
<article class="archive__item" itemscope itemtype="https://schema.org/CreativeWork">
<h2 class="archive__item-title no_toc" itemprop="headline">
<a href="/2021/12/24/first-blog-post.html" rel="permalink">First blog post
</a>
</h2>
<p class="page__meta">
<span class="page__meta-date">
<i class="far fa-fw fa-calendar-alt" aria-hidden="true"></i>
<time datetime="2021-12-24T23:54:08+00:00">December 24, 2021</time>
</span>
<span class="page__meta-sep"></span>
<span class="page__meta-readtime">
<i class="far fa-fw fa-clock" aria-hidden="true"></i>
3 minute read
</span>
</p>
<p class="archive__item-excerpt" itemprop="description">Hello, World!* So here I am and welcome to my first blog. Having a personal space on the Internet has been a dream for me for years and I am happy that it fi…
</p>
</article>
</div>
</div> </div>
</div> </div>

94
2022/01/04/build-and-deploy-automatically.html
View File

@ -552,6 +552,53 @@ WantedBy=multi-user.target
<div class="grid__item">
<article class="archive__item" itemscope itemtype="https://schema.org/CreativeWork">
<h2 class="archive__item-title no_toc" itemprop="headline">
<a href="/2022/02/27/creating-a-useless-user.html" rel="permalink">Creating a <em>Useless</em> User
</a>
</h2>
<p class="page__meta">
<span class="page__meta-date">
<i class="far fa-fw fa-calendar-alt" aria-hidden="true"></i>
<time datetime="2022-02-27T13:40:00+00:00">February 27, 2022</time>
</span>
<span class="page__meta-sep"></span>
<span class="page__meta-readtime">
<i class="far fa-fw fa-clock" aria-hidden="true"></i>
1 minute read
</span>
</p>
<p class="archive__item-excerpt" itemprop="description">Story
In my previous post, I explained how to do port forwarding to access some machine behind private network. I will use this method to fix some issues in ...</p>
</article>
</div>
<div class="grid__item"> <div class="grid__item">
<article class="archive__item" itemscope itemtype="https://schema.org/CreativeWork"> <article class="archive__item" itemscope itemtype="https://schema.org/CreativeWork">
@ -690,53 +737,6 @@ I’m sure that you run a command something like above at least once if you are
</div> </div>
<div class="grid__item">
<article class="archive__item" itemscope itemtype="https://schema.org/CreativeWork">
<h2 class="archive__item-title no_toc" itemprop="headline">
<a href="/2021/12/24/first-blog-post.html" rel="permalink">First blog post
</a>
</h2>
<p class="page__meta">
<span class="page__meta-date">
<i class="far fa-fw fa-calendar-alt" aria-hidden="true"></i>
<time datetime="2021-12-24T23:54:08+00:00">December 24, 2021</time>
</span>
<span class="page__meta-sep"></span>
<span class="page__meta-readtime">
<i class="far fa-fw fa-clock" aria-hidden="true"></i>
3 minute read
</span>
</p>
<p class="archive__item-excerpt" itemprop="description">Hello, World!* So here I am and welcome to my first blog. Having a personal space on the Internet has been a dream for me for years and I am happy that it fi…
</p>
</article>
</div>
</div> </div>
</div> </div>

94
2022/01/21/ffmpeg-to-rescue.html
View File

@ -391,6 +391,53 @@ ffmpeg <span class="nt">-f</span> concat <span class="nt">-i</span> mylist.txt <
<div class="grid__item">
<article class="archive__item" itemscope itemtype="https://schema.org/CreativeWork">
<h2 class="archive__item-title no_toc" itemprop="headline">
<a href="/2022/02/27/creating-a-useless-user.html" rel="permalink">Creating a <em>Useless</em> User
</a>
</h2>
<p class="page__meta">
<span class="page__meta-date">
<i class="far fa-fw fa-calendar-alt" aria-hidden="true"></i>
<time datetime="2022-02-27T13:40:00+00:00">February 27, 2022</time>
</span>
<span class="page__meta-sep"></span>
<span class="page__meta-readtime">
<i class="far fa-fw fa-clock" aria-hidden="true"></i>
1 minute read
</span>
</p>
<p class="archive__item-excerpt" itemprop="description">Story
In my previous post, I explained how to do port forwarding to access some machine behind private network. I will use this method to fix some issues in ...</p>
</article>
</div>
<div class="grid__item"> <div class="grid__item">
<article class="archive__item" itemscope itemtype="https://schema.org/CreativeWork"> <article class="archive__item" itemscope itemtype="https://schema.org/CreativeWork">
@ -528,53 +575,6 @@ I’m sure that you run a command something like above at least once if you are
</div> </div>
<div class="grid__item">
<article class="archive__item" itemscope itemtype="https://schema.org/CreativeWork">
<h2 class="archive__item-title no_toc" itemprop="headline">
<a href="/2021/12/24/first-blog-post.html" rel="permalink">First blog post
</a>
</h2>
<p class="page__meta">
<span class="page__meta-date">
<i class="far fa-fw fa-calendar-alt" aria-hidden="true"></i>
<time datetime="2021-12-24T23:54:08+00:00">December 24, 2021</time>
</span>
<span class="page__meta-sep"></span>
<span class="page__meta-readtime">
<i class="far fa-fw fa-clock" aria-hidden="true"></i>
3 minute read
</span>
</p>
<p class="archive__item-excerpt" itemprop="description">Hello, World!* So here I am and welcome to my first blog. Having a personal space on the Internet has been a dream for me for years and I am happy that it fi…
</p>
</article>
</div>
</div> </div>
</div> </div>

97
2022/02/26/ssh-into-machine-that-is-behind-private-network.html
View File

@ -390,7 +390,8 @@ ssh <span class="nt">-p</span> 7777 homeuser@localhost
">Previous</a> ">Previous</a>
<a href="#" class="pagination--pager disabled">Next</a> <a href="/2022/02/27/creating-a-useless-user.html" class="pagination--pager" title="Creating a Useless User
">Next</a>
</nav> </nav>
@ -409,6 +410,53 @@ ssh <span class="nt">-p</span> 7777 homeuser@localhost
<div class="grid__item">
<article class="archive__item" itemscope itemtype="https://schema.org/CreativeWork">
<h2 class="archive__item-title no_toc" itemprop="headline">
<a href="/2022/02/27/creating-a-useless-user.html" rel="permalink">Creating a <em>Useless</em> User
</a>
</h2>
<p class="page__meta">
<span class="page__meta-date">
<i class="far fa-fw fa-calendar-alt" aria-hidden="true"></i>
<time datetime="2022-02-27T13:40:00+00:00">February 27, 2022</time>
</span>
<span class="page__meta-sep"></span>
<span class="page__meta-readtime">
<i class="far fa-fw fa-clock" aria-hidden="true"></i>
1 minute read
</span>
</p>
<p class="archive__item-excerpt" itemprop="description">Story
In my previous post, I explained how to do port forwarding to access some machine behind private network. I will use this method to fix some issues in ...</p>
</article>
</div>
<div class="grid__item"> <div class="grid__item">
<article class="archive__item" itemscope itemtype="https://schema.org/CreativeWork"> <article class="archive__item" itemscope itemtype="https://schema.org/CreativeWork">
@ -546,53 +594,6 @@ I’m sure that you run a command something like above at least once if you are
</div> </div>
<div class="grid__item">
<article class="archive__item" itemscope itemtype="https://schema.org/CreativeWork">
<h2 class="archive__item-title no_toc" itemprop="headline">
<a href="/2021/12/24/first-blog-post.html" rel="permalink">First blog post
</a>
</h2>
<p class="page__meta">
<span class="page__meta-date">
<i class="far fa-fw fa-calendar-alt" aria-hidden="true"></i>
<time datetime="2021-12-24T23:54:08+00:00">December 24, 2021</time>
</span>
<span class="page__meta-sep"></span>
<span class="page__meta-readtime">
<i class="far fa-fw fa-clock" aria-hidden="true"></i>
3 minute read
</span>
</p>
<p class="archive__item-excerpt" itemprop="description">Hello, World!* So here I am and welcome to my first blog. Having a personal space on the Internet has been a dream for me for years and I am happy that it fi…
</p>
</article>
</div>
</div> </div>
</div> </div>

649
2022/02/27/creating-a-useless-user.html Normal file
View File

@ -0,0 +1,649 @@
<!doctype html>
<!--
Minimal Mistakes Jekyll Theme 4.24.0 by Michael Rose
Copyright 2013-2020 Michael Rose - mademistakes.com | @mmistakes
Free for personal and commercial use under the MIT license
https://github.com/mmistakes/minimal-mistakes/blob/master/LICENSE
-->
<html lang="en" class="no-js">
<head>
<meta charset="utf-8">
<!-- begin _includes/seo.html --><title>Creating a Useless User - Şahin Akkaya’s Personal Page</title>
<meta name="description" content="Story In my previous post, I explained how to do port forwarding to access some machine behind private network. I will use this method to fix some issues in our desktop at home or my girlfriend’s computer. Now, of course I don’t want to give them access to my server. But they also need to have a user in my server to be able to perform port forwarding via ssh. So I wanted to create a user with least privileges to make sure nothing goes wrong.">
<meta name="author" content="Şahin Akkaya">
<meta property="article:author" content="Şahin Akkaya">
<meta property="og:type" content="article">
<meta property="og:locale" content="en_US">
<meta property="og:site_name" content="Şahin Akkaya's Personal Page">
<meta property="og:title" content="Creating a Useless User">
<meta property="og:url" content="https://sahinakkaya.dev/2022/02/27/creating-a-useless-user.html">
<meta property="og:description" content="Story In my previous post, I explained how to do port forwarding to access some machine behind private network. I will use this method to fix some issues in our desktop at home or my girlfriend’s computer. Now, of course I don’t want to give them access to my server. But they also need to have a user in my server to be able to perform port forwarding via ssh. So I wanted to create a user with least privileges to make sure nothing goes wrong.">
<meta property="article:published_time" content="2022-02-27T13:40:00+00:00">
<link rel="canonical" href="https://sahinakkaya.dev/2022/02/27/creating-a-useless-user.html">
<script type="application/ld+json">
{
"@context": "https://schema.org",
"@type": "Person",
"name": null,
"url": "https://sahinakkaya.dev/"
}
</script>
<!-- end _includes/seo.html -->
<link href="/feed.xml" type="application/atom+xml" rel="alternate" title="Şahin Akkaya's Personal Page Feed">
<!-- https://t.co/dKP3o1e -->
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<script>
document.documentElement.className = document.documentElement.className.replace(/\bno-js\b/g, '') + ' js ';
</script>
<!-- For all browsers -->
<link rel="stylesheet" href="/assets/css/main.css">
<link rel="preload" href="https://cdn.jsdelivr.net/npm/@fortawesome/fontawesome-free@5/css/all.min.css" as="style" onload="this.onload=null;this.rel='stylesheet'">
<noscript><link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/@fortawesome/fontawesome-free@5/css/all.min.css"></noscript>
<!-- start custom head snippets -->
<!-- insert favicons. use https://realfavicongenerator.net/ -->
<!-- end custom head snippets -->
</head>
<body class="layout--single">
<nav class="skip-links">
<ul>
<li><a href="#site-nav" class="screen-reader-shortcut">Skip to primary navigation</a></li>
<li><a href="#main" class="screen-reader-shortcut">Skip to content</a></li>
<li><a href="#footer" class="screen-reader-shortcut">Skip to footer</a></li>
</ul>
</nav>
<!--[if lt IE 9]>
<div class="notice--danger align-center" style="margin: 0;">You are using an <strong>outdated</strong> browser. Please <a href="https://browsehappy.com/">upgrade your browser</a> to improve your experience.</div>
<![endif]-->
<div class="masthead">
<div class="masthead__inner-wrap">
<div class="masthead__menu">
<nav id="site-nav" class="greedy-nav">
<a class="site-title" href="/">
/home/sahin/
</a>
<ul class="visible-links"><li class="masthead__menu-item">
<a href="/">Home</a>
</li><li class="masthead__menu-item">
<a href="/about/">About</a>
</li><li class="masthead__menu-item">
<a href="/contact/">Contact</a>
</li></ul>
<button class="search__toggle" type="button">
<span class="visually-hidden">Toggle search</span>
<i class="fas fa-search"></i>
</button>
<button class="greedy-nav__toggle hidden" type="button">
<span class="visually-hidden">Toggle menu</span>
<div class="navicon"></div>
</button>
<ul class="hidden-links hidden"></ul>
</nav>
</div>
</div>
</div>
<div class="initial-content">
<div id="main" role="main">
<div class="sidebar sticky">
<div itemscope itemtype="https://schema.org/Person">
<div class="author__avatar">
<img src="/assets/images/logo.jpg" alt="Şahin Akkaya" itemprop="image">
</div>
<div class="author__content">
<h3 class="author__name" itemprop="name">Şahin Akkaya</h3>
<div class="author__bio" itemprop="description">
<p>A perfectionist who likes to tinker everything until it is just right.</p>
</div>
</div>
<div class="author__urls-wrapper">
<button class="btn btn--inverse">Follow</button>
<ul class="author__urls social-icons">
<li itemprop="homeLocation" itemscope itemtype="https://schema.org/Place">
<i class="fas fa-fw fa-map-marker-alt" aria-hidden="true"></i> <span itemprop="name">Istanbul, Turkey</span>
</li>
<li><a href="https://github.com/Asocia" rel="nofollow noopener noreferrer"><i class="fab fa-fw fa-github" aria-hidden="true"></i><span class="label">Asocia</span></a></li>
<li><a href="https://stackoverflow.com/users/9608759" rel="nofollow noopener noreferrer"><i class="fab fa-fw fa-stack-overflow" aria-hidden="true"></i><span class="label">Asocia</span></a></li>
<li><a href="https://twitter.com/sahinakkayadev" rel="nofollow noopener noreferrer"><i class="fab fa-fw fa-twitter-square" aria-hidden="true"></i><span class="label">@sahinakkayadev</span></a></li>
<li><a href="mailto:sahin@sahinakkaya.dev" rel="nofollow noopener noreferrer"><i class="fas fa-fw fa-envelope" aria-hidden="true"></i><span class="label">sahin@sahinakkaya.dev</span></a></li>
<li><a href="/assets/docs/resume.pdf" rel="nofollow noopener noreferrer"><i class="fas fa-fw fa-id-card" aria-hidden="true"></i><span class="label">Resume</span></a></li>
<!--
<li>
<a href="http://link-to-whatever-social-network.com/user/" itemprop="sameAs" rel="nofollow noopener noreferrer">
<i class="fas fa-fw" aria-hidden="true"></i> Custom Social Profile Link
</a>
</li>
-->
</ul>
</div>
</div>
</div>
<article class="page" itemscope itemtype="https://schema.org/CreativeWork">
<meta itemprop="headline" content="Creating a Useless User">
<meta itemprop="description" content="StoryIn my previous post, I explained how to do port forwarding to access some machine behind private network. I will use this method to fix some issues in our desktop at home or my girlfriend’s computer. Now, of course I don’t want to give them access to my server. But they also need to have a user in my server to be able to perform port forwarding via ssh. So I wanted to create a user with least privileges to make sure nothing goes wrong.">
<meta itemprop="datePublished" content="2022-02-27T13:40:00+00:00">
<div class="page__inner-wrap">
<header>
<h1 id="page-title" class="page__title" itemprop="headline">Creating a <em>Useless</em> User
</h1>
<p class="page__meta">
<span class="page__meta-date">
<i class="far fa-calendar-alt" aria-hidden="true"></i>
<time datetime="2022-02-27T13:40:00+00:00">February 27, 2022</time>
</span>
<span class="page__meta-sep"></span>
<span class="page__meta-readtime">
<i class="far fa-clock" aria-hidden="true"></i>
1 minute read
</span>
</p>
</header>
<section class="page__content" itemprop="text">
<h2 id="story">Story</h2>
<p>In my <a href="/2022/02/26/ssh-into-machine-that-is-behind-private-network.html">previous post</a>, I explained how to do port forwarding to access some machine behind private network. I will use this method to fix some issues in our desktop at home or my girlfriend’s computer. Now, of course I don’t want to give them access to my server. But they also need to have a user in my server to be able to perform port forwarding via ssh. So I wanted to create a user with least privileges to make sure nothing goes wrong.</p>
<h2 id="the-solution">The solution</h2>
<p>I searched the problem in it turned out to be very simple. You just need to add two additional flags to <code class="language-plaintext highlighter-rouge">adduser</code> command while creating the user.</p>
<div class="language-bash highlighter-rouge"><div class="highlight"><pre class="highlight"><code><span class="nb">sudo </span>adduser uselessuser <span class="nt">--shell</span><span class="o">=</span>/bin/false <span class="nt">--no-create-home</span>
</code></pre></div></div>
<p>Now, <code class="language-plaintext highlighter-rouge">uselessuser</code> can’t do anything useful in your server. If they try to login, the connection will be closed immediately.</p>
<div class="language-bash highlighter-rouge"><div class="highlight"><pre class="highlight"><code>❯ ssh uselessuser@remote.host
uselessuser@remote.host<span class="se">\'</span>s password:
Could not chdir to home directory /home/uselessuser: No such file or directory
Connection to remote.host closed.
</code></pre></div></div>
<p>But they can still do forward the remote port to their local machine.</p>
<div class="language-bash highlighter-rouge"><div class="highlight"><pre class="highlight"><code>❯ ssh <span class="nt">-Nf</span> <span class="nt">-R</span> 7777:localhost:22 uselessuser@remote.host
uselessuser@remote.host<span class="se">\'</span>s password:
</code></pre></div></div>
<p>The <code class="language-plaintext highlighter-rouge">-N</code> option is the most important one here. From the documentation:</p>
<blockquote>
<div class="language-plaintext highlighter-rouge"><div class="highlight"><pre class="highlight"><code> -N Do not execute a remote command. This is useful
for just forwarding ports. Refer to the description
of SessionType in ssh_config(5) for details.
</code></pre></div> </div>
</blockquote>
<h2 id="last-words">Last words</h2>
<p>I love learning new things everyday. I knew setting the shell of a user to <code class="language-plaintext highlighter-rouge">/bin/false</code> will prevent them from logging in. The reason I wrote this blog post is because 2 things I wanted to share:</p>
<ul>
<li>While looking for a solution to the problem I mentioned, I searched <em>“create a user with no privileges in linux”</em> and <a href="https://askubuntu.com/questions/1174376/how-to-create-a-user-with-the-least-privileges-permissions-but-enough-to-do-ssh">this</a> came out. It is really interesting for me that another person wanted to do the same thing for the <em>exact same reasons</em>. They were also trying port forwarding via ssh and they wanted to create a limited user in their server to give friends. So the question was a <strong>perfect fit</strong> to the problem.</li>
<li>The <code class="language-plaintext highlighter-rouge">-N</code> flag of the ssh command was also surprising for me. It was like as if someone had encountered these problems before and just took the exact steps required to solve this problem for me. I mean look at the documentation. Crazy!</li>
</ul>
</section>
<footer class="page__meta">
<p class="page__date"><strong><i class="fas fa-fw fa-calendar-alt" aria-hidden="true"></i> Updated:</strong> <time datetime="2022-02-27T13:40:00+00:00">February 27, 2022</time></p>
</footer>
<section class="page__share">
<a href="https://twitter.com/intent/tweet?text=Creating+a+%2AUseless%2A+User%20https%3A%2F%2Fsahinakkaya.dev%2F2022%2F02%2F27%2Fcreating-a-useless-user.html" class="btn btn--twitter" onclick="window.open(this.href, 'window', 'left=20,top=20,width=500,height=500,toolbar=1,resizable=0'); return false;" title="Share on Twitter"><i class="fab fa-fw fa-twitter" aria-hidden="true"></i><span> Twitter</span></a>
<a href="https://www.facebook.com/sharer/sharer.php?u=https%3A%2F%2Fsahinakkaya.dev%2F2022%2F02%2F27%2Fcreating-a-useless-user.html" class="btn btn--facebook" onclick="window.open(this.href, 'window', 'left=20,top=20,width=500,height=500,toolbar=1,resizable=0'); return false;" title="Share on Facebook"><i class="fab fa-fw fa-facebook" aria-hidden="true"></i><span> Facebook</span></a>
<a href="https://www.linkedin.com/shareArticle?mini=true&url=https%3A%2F%2Fsahinakkaya.dev%2F2022%2F02%2F27%2Fcreating-a-useless-user.html" class="btn btn--linkedin" onclick="window.open(this.href, 'window', 'left=20,top=20,width=500,height=500,toolbar=1,resizable=0'); return false;" title="Share on LinkedIn"><i class="fab fa-fw fa-linkedin" aria-hidden="true"></i><span> LinkedIn</span></a>
</section>
<nav class="pagination">
<a href="/2022/02/26/ssh-into-machine-that-is-behind-private-network.html" class="pagination--pager" title="SSH into Machine That Is Behind a Private Network
">Previous</a>
<a href="#" class="pagination--pager disabled">Next</a>
</nav>
</div>
</article>
<div class="page__related">
<h4 class="page__related-title">You May Also Enjoy</h4>
<div class="grid__wrapper">
<div class="grid__item">
<article class="archive__item" itemscope itemtype="https://schema.org/CreativeWork">
<h2 class="archive__item-title no_toc" itemprop="headline">
<a href="/2022/02/26/ssh-into-machine-that-is-behind-private-network.html" rel="permalink">SSH into Machine That Is Behind a Private Network
</a>
</h2>
<p class="page__meta">
<span class="page__meta-date">
<i class="far fa-fw fa-calendar-alt" aria-hidden="true"></i>
<time datetime="2022-02-26T21:40:00+00:00">February 26, 2022</time>
</span>
<span class="page__meta-sep"></span>
<span class="page__meta-readtime">
<i class="far fa-fw fa-clock" aria-hidden="true"></i>
2 minute read
</span>
</p>
<p class="archive__item-excerpt" itemprop="description">Story
I believe there is always a “tech support person” in every home. Everyone knows that when there is a problem with any electronic device, they should as...</p>
</article>
</div>
<div class="grid__item">
<article class="archive__item" itemscope itemtype="https://schema.org/CreativeWork">
<h2 class="archive__item-title no_toc" itemprop="headline">
<a href="/2022/01/21/ffmpeg-to-rescue.html" rel="permalink">Using ffmpeg for Simple Video Editing
</a>
</h2>
<p class="page__meta">
<span class="page__meta-date">
<i class="far fa-fw fa-calendar-alt" aria-hidden="true"></i>
<time datetime="2022-01-21T20:40:00+00:00">January 21, 2022</time>
</span>
<span class="page__meta-sep"></span>
<span class="page__meta-readtime">
<i class="far fa-fw fa-clock" aria-hidden="true"></i>
1 minute read
</span>
</p>
<p class="archive__item-excerpt" itemprop="description">Story
Today, I have recorded a video for one of my classes and I was required to upload it till midnight. The video was perfect except for a few seconds wher...</p>
</article>
</div>
<div class="grid__item">
<article class="archive__item" itemscope itemtype="https://schema.org/CreativeWork">
<h2 class="archive__item-title no_toc" itemprop="headline">
<a href="/2022/01/04/build-and-deploy-automatically.html" rel="permalink">Automatically Build and Deploy Your Site using GitHub Actions and Webhooks
</a>
</h2>
<p class="page__meta">
<span class="page__meta-date">
<i class="far fa-fw fa-calendar-alt" aria-hidden="true"></i>
<time datetime="2022-01-04T17:40:00+00:00">January 4, 2022</time>
</span>
<span class="page__meta-sep"></span>
<span class="page__meta-readtime">
<i class="far fa-fw fa-clock" aria-hidden="true"></i>
5 minute read
</span>
</p>
<p class="archive__item-excerpt" itemprop="description">In this post I will explain how you can use GitHub to automate the build and deployment processes that you have. I am going to automate the deployment of thi...</p>
</article>
</div>
<div class="grid__item">
<article class="archive__item" itemscope itemtype="https://schema.org/CreativeWork">
<h2 class="archive__item-title no_toc" itemprop="headline">
<a href="/2022/01/01/stop-cat-pipeing.html" rel="permalink">Stop cat-pipe’ing, You Are Doing It Wrong!
</a>
</h2>
<p class="page__meta">
<span class="page__meta-date">
<i class="far fa-fw fa-calendar-alt" aria-hidden="true"></i>
<time datetime="2022-01-01T15:00:00+00:00">January 1, 2022</time>
</span>
<span class="page__meta-sep"></span>
<span class="page__meta-readtime">
<i class="far fa-fw fa-clock" aria-hidden="true"></i>
2 minute read
</span>
</p>
<p class="archive__item-excerpt" itemprop="description">cat some_file | grep some_pattern
I’m sure that you run a command something like above at least once if you are using terminal. You know how cat and grep wo...</p>
</article>
</div>
</div>
</div>
</div>
</div>
<div class="search-content">
<div class="search-content__inner-wrap"><form class="search-content__form" onkeydown="return event.key != 'Enter';">
<label class="sr-only" for="search">
Enter your search term...
</label>
<input type="search" id="search" class="search-input" tabindex="-1" placeholder="Enter your search term..." />
</form>
<div id="results" class="results"></div></div>
</div>
<div id="footer" class="page__footer">
<footer>
<!-- start custom footer snippets -->
<!-- end custom footer snippets -->
<div class="page__footer-follow">
<ul class="social-icons">
<li><a href="/feed.xml"><i class="fas fa-fw fa-rss-square" aria-hidden="true"></i> Feed</a></li>
</ul>
</div>
<div class="page__footer-copyright">&copy; 2022 Şahin Akkaya's Personal Page. Powered by <a href="https://jekyllrb.com" rel="nofollow">Jekyll</a> &amp; <a href="https://mademistakes.com/work/minimal-mistakes-jekyll-theme/" rel="nofollow">Minimal Mistakes</a>.</div>
<div class="page__footer-copyright">
Check out the <a href="https://github.com/Asocia/sahinakkayadotdev">code</a> of this site.
</div>
</footer>
</div>
<script src="/assets/js/main.min.js"></script>
<script src="/assets/js/lunr/lunr.min.js"></script>
<script src="/assets/js/lunr/lunr-store.js"></script>
<script src="/assets/js/lunr/lunr-en.js"></script>
</body>
</html>

6
assets/js/lunr/lunr-store.js
View File

@ -28,4 +28,10 @@ var store = [{
"tags": ["ssh","private-network","remote-port-forwarding"], "tags": ["ssh","private-network","remote-port-forwarding"],
"url": "/2022/02/26/ssh-into-machine-that-is-behind-private-network.html", "url": "/2022/02/26/ssh-into-machine-that-is-behind-private-network.html",
"teaser": null "teaser": null
},{
"title": "Creating a *Useless* User",
"excerpt":"Story In my previous post, I explained how to do port forwarding to access some machine behind private network. I will use this method to fix some issues in our desktop at home or my girlfriend’s computer. Now, of course I don’t want to give them access to my server....","categories": [],
"tags": ["linux","permissions","privileges"],
"url": "/2022/02/27/creating-a-useless-user.html",
"teaser": null
}] }]

32
feed.xml
View File

@ -1,4 +1,34 @@
<?xml version="1.0" encoding="utf-8"?><feed xmlns="http://www.w3.org/2005/Atom" ><generator uri="https://jekyllrb.com/" version="4.2.1">Jekyll</generator><link href="https://sahinakkaya.dev/feed.xml" rel="self" type="application/atom+xml" /><link href="https://sahinakkaya.dev/" rel="alternate" type="text/html" /><updated>2022-02-27T05:08:20+00:00</updated><id>https://sahinakkaya.dev/feed.xml</id><title type="html">Şahin Akkaya’s Personal Page</title><subtitle>Şahin Akkaya's personal blog - a perfectionist who likes to tinker everything until it is just right. Get ready to find some sweet tips that will boost your productivity and make you fall in love with your computer.</subtitle><author><name>Şahin Akkaya</name></author><entry><title type="html">SSH into Machine That Is Behind a Private Network</title><link href="https://sahinakkaya.dev/2022/02/26/ssh-into-machine-that-is-behind-private-network.html" rel="alternate" type="text/html" title="SSH into Machine That Is Behind a Private Network" /><published>2022-02-26T21:40:00+00:00</published><updated>2022-02-26T21:40:00+00:00</updated><id>https://sahinakkaya.dev/2022/02/26/ssh-into-machine-that-is-behind-private-network</id><content type="html" xml:base="https://sahinakkaya.dev/2022/02/26/ssh-into-machine-that-is-behind-private-network.html">&lt;h2 id=&quot;story&quot;&gt;Story&lt;/h2&gt; <?xml version="1.0" encoding="utf-8"?><feed xmlns="http://www.w3.org/2005/Atom" ><generator uri="https://jekyllrb.com/" version="4.2.1">Jekyll</generator><link href="https://sahinakkaya.dev/feed.xml" rel="self" type="application/atom+xml" /><link href="https://sahinakkaya.dev/" rel="alternate" type="text/html" /><updated>2022-02-27T14:57:40+00:00</updated><id>https://sahinakkaya.dev/feed.xml</id><title type="html">Şahin Akkaya’s Personal Page</title><subtitle>Şahin Akkaya's personal blog - a perfectionist who likes to tinker everything until it is just right. Get ready to find some sweet tips that will boost your productivity and make you fall in love with your computer.</subtitle><author><name>Şahin Akkaya</name></author><entry><title type="html">Creating a *Useless* User</title><link href="https://sahinakkaya.dev/2022/02/27/creating-a-useless-user.html" rel="alternate" type="text/html" title="Creating a *Useless* User" /><published>2022-02-27T13:40:00+00:00</published><updated>2022-02-27T13:40:00+00:00</updated><id>https://sahinakkaya.dev/2022/02/27/creating-a-useless-user</id><content type="html" xml:base="https://sahinakkaya.dev/2022/02/27/creating-a-useless-user.html">&lt;h2 id=&quot;story&quot;&gt;Story&lt;/h2&gt;
&lt;p&gt;In my &lt;a href=&quot;/2022/02/26/ssh-into-machine-that-is-behind-private-network.html&quot;&gt;previous post&lt;/a&gt;, I explained how to do port forwarding to access some machine behind private network. I will use this method to fix some issues in our desktop at home or my girlfriend’s computer. Now, of course I don’t want to give them access to my server. But they also need to have a user in my server to be able to perform port forwarding via ssh. So I wanted to create a user with least privileges to make sure nothing goes wrong.&lt;/p&gt;
&lt;h2 id=&quot;the-solution&quot;&gt;The solution&lt;/h2&gt;
&lt;p&gt;I searched the problem in it turned out to be very simple. You just need to add two additional flags to &lt;code class=&quot;language-plaintext highlighter-rouge&quot;&gt;adduser&lt;/code&gt; command while creating the user.&lt;/p&gt;
&lt;div class=&quot;language-bash highlighter-rouge&quot;&gt;&lt;div class=&quot;highlight&quot;&gt;&lt;pre class=&quot;highlight&quot;&gt;&lt;code&gt;&lt;span class=&quot;nb&quot;&gt;sudo &lt;/span&gt;adduser uselessuser &lt;span class=&quot;nt&quot;&gt;--shell&lt;/span&gt;&lt;span class=&quot;o&quot;&gt;=&lt;/span&gt;/bin/false &lt;span class=&quot;nt&quot;&gt;--no-create-home&lt;/span&gt;
&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt;&lt;/div&gt;
&lt;p&gt;Now, &lt;code class=&quot;language-plaintext highlighter-rouge&quot;&gt;uselessuser&lt;/code&gt; can’t do anything useful in your server. If they try to login, the connection will be closed immediately.&lt;/p&gt;
&lt;div class=&quot;language-bash highlighter-rouge&quot;&gt;&lt;div class=&quot;highlight&quot;&gt;&lt;pre class=&quot;highlight&quot;&gt;&lt;code&gt;❯ ssh uselessuser@remote.host
uselessuser@remote.host&lt;span class=&quot;se&quot;&gt;\'&lt;/span&gt;s password:
Could not chdir to home directory /home/uselessuser: No such file or directory
Connection to remote.host closed.
&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt;&lt;/div&gt;
&lt;p&gt;But they can still do forward the remote port to their local machine.&lt;/p&gt;
&lt;div class=&quot;language-bash highlighter-rouge&quot;&gt;&lt;div class=&quot;highlight&quot;&gt;&lt;pre class=&quot;highlight&quot;&gt;&lt;code&gt;❯ ssh &lt;span class=&quot;nt&quot;&gt;-Nf&lt;/span&gt; &lt;span class=&quot;nt&quot;&gt;-R&lt;/span&gt; 7777:localhost:22 uselessuser@remote.host
uselessuser@remote.host&lt;span class=&quot;se&quot;&gt;\'&lt;/span&gt;s password:
&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt;&lt;/div&gt;
&lt;p&gt;The &lt;code class=&quot;language-plaintext highlighter-rouge&quot;&gt;-N&lt;/code&gt; option is the most important one here. From the documentation:&lt;/p&gt;
&lt;blockquote&gt;
&lt;div class=&quot;language-plaintext highlighter-rouge&quot;&gt;&lt;div class=&quot;highlight&quot;&gt;&lt;pre class=&quot;highlight&quot;&gt;&lt;code&gt; -N Do not execute a remote command. This is useful
for just forwarding ports. Refer to the description
of SessionType in ssh_config(5) for details.
&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt; &lt;/div&gt;
&lt;/blockquote&gt;
&lt;h2 id=&quot;last-words&quot;&gt;Last words&lt;/h2&gt;
&lt;p&gt;I love learning new things everyday. I knew setting the shell of a user to &lt;code class=&quot;language-plaintext highlighter-rouge&quot;&gt;/bin/false&lt;/code&gt; will prevent them from logging in. The reason I wrote this blog post is because 2 things I wanted to share:&lt;/p&gt;
&lt;ul&gt;
&lt;li&gt;While looking for a solution to the problem I mentioned, I searched &lt;em&gt;“create a user with no privileges in linux”&lt;/em&gt; and &lt;a href=&quot;https://askubuntu.com/questions/1174376/how-to-create-a-user-with-the-least-privileges-permissions-but-enough-to-do-ssh&quot;&gt;this&lt;/a&gt; came out. It is really interesting for me that another person wanted to do the same thing for the &lt;em&gt;exact same reasons&lt;/em&gt;. They were also trying port forwarding via ssh and they wanted to create a limited user in their server to give friends. So the question was a &lt;strong&gt;perfect fit&lt;/strong&gt; to the problem.&lt;/li&gt;
&lt;li&gt;The &lt;code class=&quot;language-plaintext highlighter-rouge&quot;&gt;-N&lt;/code&gt; flag of the ssh command was also surprising for me. It was like as if someone had encountered these problems before and just took the exact steps required to solve this problem for me. I mean look at the documentation. Crazy!&lt;/li&gt;
&lt;/ul&gt;</content><author><name>Şahin Akkaya</name></author><category term="linux" /><category term="permissions" /><category term="privileges" /><summary type="html">Story In my previous post, I explained how to do port forwarding to access some machine behind private network. I will use this method to fix some issues in our desktop at home or my girlfriend’s computer. Now, of course I don’t want to give them access to my server. But they also need to have a user in my server to be able to perform port forwarding via ssh. So I wanted to create a user with least privileges to make sure nothing goes wrong.</summary></entry><entry><title type="html">SSH into Machine That Is Behind a Private Network</title><link href="https://sahinakkaya.dev/2022/02/26/ssh-into-machine-that-is-behind-private-network.html" rel="alternate" type="text/html" title="SSH into Machine That Is Behind a Private Network" /><published>2022-02-26T21:40:00+00:00</published><updated>2022-02-26T21:40:00+00:00</updated><id>https://sahinakkaya.dev/2022/02/26/ssh-into-machine-that-is-behind-private-network</id><content type="html" xml:base="https://sahinakkaya.dev/2022/02/26/ssh-into-machine-that-is-behind-private-network.html">&lt;h2 id=&quot;story&quot;&gt;Story&lt;/h2&gt;
&lt;p&gt;I believe there is always a “tech support person” in every home. Everyone knows that when there is a problem with any electronic device, they should ask this person. I am the tech support in our house. Today, I had to fix a problem in our desktop. Since I was not at home, I had to fix the problem remotely.&lt;/p&gt; &lt;p&gt;I believe there is always a “tech support person” in every home. Everyone knows that when there is a problem with any electronic device, they should ask this person. I am the tech support in our house. Today, I had to fix a problem in our desktop. Since I was not at home, I had to fix the problem remotely.&lt;/p&gt;
&lt;h2 id=&quot;possible-solutions&quot;&gt;Possible solutions&lt;/h2&gt; &lt;h2 id=&quot;possible-solutions&quot;&gt;Possible solutions&lt;/h2&gt;

47
index.html
View File

@ -284,6 +284,53 @@
<div class="list__item">
<article class="archive__item" itemscope itemtype="https://schema.org/CreativeWork">
<h2 class="archive__item-title no_toc" itemprop="headline">
<a href="/2022/02/27/creating-a-useless-user.html" rel="permalink">Creating a <em>Useless</em> User
</a>
</h2>
<p class="page__meta">
<span class="page__meta-date">
<i class="far fa-calendar-alt" aria-hidden="true"></i>
<time datetime="2022-02-27T13:40:00+00:00">February 27, 2022</time>
</span>
<span class="page__meta-sep"></span>
<span class="page__meta-readtime">
<i class="far fa-clock" aria-hidden="true"></i>
1 minute read
</span>
</p>
<p class="archive__item-excerpt" itemprop="description">Story
In my previous post, I explained how to do port forwarding to access some machine behind private network. I will use this method to fix some issues in ...</p>
</article>
</div>
<div class="list__item"> <div class="list__item">
<article class="archive__item" itemscope itemtype="https://schema.org/CreativeWork"> <article class="archive__item" itemscope itemtype="https://schema.org/CreativeWork">

6
sitemap.xml
View File

@ -21,6 +21,10 @@
<lastmod>2022-02-26T21:40:00+00:00</lastmod> <lastmod>2022-02-26T21:40:00+00:00</lastmod>
</url> </url>
<url> <url>
<loc>https://sahinakkaya.dev/2022/02/27/creating-a-useless-user.html</loc>
<lastmod>2022-02-27T13:40:00+00:00</lastmod>
</url>
<url>
<loc>https://sahinakkaya.dev/about/</loc> <loc>https://sahinakkaya.dev/about/</loc>
</url> </url>
<url> <url>
@ -31,6 +35,6 @@
</url> </url>
<url> <url>
<loc>https://sahinakkaya.dev/assets/docs/resume.pdf</loc> <loc>https://sahinakkaya.dev/assets/docs/resume.pdf</loc>
<lastmod>2022-02-27T05:03:18+00:00</lastmod> <lastmod>2022-02-27T14:57:35+00:00</lastmod>
</url> </url>
</urlset> </urlset>