connecting.shtml

---
layout: default
title: Connecting to CHTC
---

This guide assumes that you have already gotten a CHTC account for either 
our high throughput or high performance compute systems.  If you haven't, 
see our <a href="{{'/get-started' | relative_url }}">getting started</a> page.

<h1>Contents</h1>

<ol>
  <li><a href="">Accessing the Submit Servers</a></li>
  <li><a href="#login">Logging In</a>
    <ul>
    <li><a href="#login-ssh">On the command line (Mac/Linux)</a></li>  
    <li><a href="#login-putty">Using an SSH program (Windows/Mac)</a></li>
    <li><a href="#ssh-keys">Logging in Automatically</a></li>
    </ul></li>
  <li><a href="#transfer">Transferring Files</a>
    <ul>
    <li><a href="#transfer-scp">On the command line (Mac/Linux)</a></li>
    <li><a href="#transfer-winscp">Using a file transfer program (Windows/Mac)</a></li>
    <li><a href="#transfer-winscp">Transferring Multiple Files</a></li>
    </ul></li>
  <li><a href="#files">Creating and Editing Files</a></li>
  <li><a href="#learn">Learning about the command line</a></li>
</ol>

<a name="access"></a>
<h1>1. Accessing the Submit Servers</h1>

<p>You will need the following information to log into our CHTC submit 
servers or head nodes: </p>

<b>Username and Password</b><br>

<ul>
	<li>UW Madison users: Wisconsin NetId and password</li>
	<li>Off-campus users: varies, by request</li>
</ul>

<b>Hostname</b><br>

<table class="gtable">
 <tr>
   <th>HTC System</th>
 </tr>
 <tr>
   <td><code>submit-1.chtc.wisc.edu</code> - typically for accounts created between Aug 2018 - June 2019</td>
 </tr>
 <tr>
   <td><code>submit2.chtc.wisc.edu</code> - typically for accounts created prior to Aug 2018 or after June 2019</td>
 </tr>
</table>

<table class="gtable">
 <tr>
   <th>HPC Cluster</th>
 </tr>
 <tr>
   <td><code>aci-service-1.chtc.wisc.edu</code> and/or <code>aci-service-2.chtc.wisc.edu</code></td>
 </tr>
</table>

<blockquote>
<b>Are you off-campus?</b> <br>
All of our CHTC submit servers and head nodes are firewalled 
to block log-ins from off-campus.  If you are off-campus and want to log in, 
you can either:
<ul>
<li>Activate the campus VPN (more details on how to set this up
<a href="https://it.wisc.edu/services/wiscvpn/">here</a>).</li>
<li>Log into another computer that is on campus.</li>
</ul>
In either case, it will appear like you are on-campus, and you should then be able 
to log into CHTC as usual.  
</blockquote>

<a name="login"></a>
<h1>2. Logging In</h1>

<p>Using the information described above, you can log in to servers 
two different ways -- from the command line or using an SSH program: </p>

<a name="login-ssh"></a>
<h2>A. On the command line (Mac/Linux)</h2>

<p>On a Mac or Linux system, you can use the "Terminal" application to 
log in.  Open a terminal window and use the following command to 
connect to the appropriate server:</p>
<pre class="term">$ ssh <i>username</i>@<i>hostname</i></pre>
<p>You will be prompted for your password.</p>

<a name="login-putty"></a>
<h2>B. Using an SSH program (Windows)</h2>

<p>There are multiple programs to connect to remote servers for Windows.  
We recommend "PuTTy", which can be downloaded <a href="https://www.chiark.greenend.org.uk/~sgtatham/putty/latest.html">here</a>.  To 
log in, click on the PuTTy executable (<code>putty.exe</code>).  You should 
see a screen like this: </p>

<img src="/images/putty-7.jpeg">

<p>Fill in the hostname as described in part 1.  You should use Port 22
 and connect using "ssh" -- these are usually the defaults.  After
you click "connect" 
you will be prompted to fill in your username and password.  </p>

<p>Note that once you have submitted jobs to the queue, you can leave your 
logged in session (by typing <code>exit</code>).  Your jobs will run 
and return output without you needing to be connected.  </p>

<a name="ssh-keys"></a>
<h2>C. Logging in automatically </h2>

<p>Tired of typing your password everytime you log in?  It's possible to set 
up a file on your local computer called an ssh key, that allows you to log 
into CHTC and transfer files without entering your password.  
<a href="http://www.howtogeek.com/66776/how-to-remotely-copy-files-over-ssh-without-entering-your-password/"> See
this guide</a> for instructions on how to do this, starting at the section titled 
<b>"SSH and SCP Without Passwords"</b>.  </p>

<a name="transfer"></a>
<h1>3. Transferring Files</h1>

<p>To transfer files to and from CHTC, you will need the same username 
and hostname information for <a href="#login">logging in</a>, as well 
as understanding where your files are and where you would like them to go.  </p>

<a name="transfer-scp"></a>
<h2>A. On the command line (Mac/Linux)</h2>

<p>On a Mac or Linux system, you can use the "Terminal" application and 
the <code>scp</code> command to copy files between your computer and 
CHTC servers.</p>

<b>Your computer to CHTC</b><br>

<p>First, open the "Terminal" application and navigate to the 
directory with the files or directories you want to transfer.  Then, 
use this command to copy these files to CHTC: </p>

<pre class="term">$ scp <i>file username@hostname:/home/username</i></pre>

<p>If you would like these files to end up in a different directory inside your 
home directory, just add it to the path at the end of the command.  </p>

<b>CHTC to your computer</b><br>

<p>Open the "Terminal" application.  Do NOT log into CHTC.  Instead, 
navigate to where you want the files to go on your computer.  Then, 
use this command to copy these files there:</p>

<pre class="term">$ scp <i>username@hostname:/home/username/file</i> ./</pre>

Again, for many files, it will be easiest to create a compressed tarball (.tar.gz file)
of your files and transfer that instead of each file individually.  

<a name="transfer-winscp"></a>
<h2>B. Using a file transfer program (Windows/Mac)</h2>

<p>Windows and Mac users can also use special programs to help them 
transfer files between their computers and CHTC.  For Windows, we 
recommend <a href="https://winscp.net/eng/download.php">WinSCP</a>.  It requires the same information as 
Putty (hostname, username), and once it's set up, looks like this: </p>

<img src="/images/WinSCPPortable.png">

<p>The left window is a directory on your computer, the right window is 
your home directory in CHTC.  To move files between the two, simply drag and drop.  </p>

<p>There are other programs besides WinSCP that do this.  Another that 
works on Mac and Windows is called <a href="https://cyberduck.io">Cyberduck</a>.</p>

<a name="transfer-many"></a>
<h2>C. Transferring Multiple Files </h2>

<p>If you are transferring many files, it is advantageous to compress 
them into a single compressed file, in order to facilitate transferring 
them.  Place all the files you need in a directory, and then either 
zip it or use the "tar" command to compress them: </p>

<pre class="term">
$ tar czf data_files.tar.gz <i>file_directory/</i>
</pre>

To untar or unzip files on the submit server or head nodes, you can use either: 

<pre class="term">[alice@submit]$ tar xzf data_files.tar.gz</pre>
or
<pre class="term">[alice@submit]$ unzip data_files.zip</pre>

<a name="files"></a>
<h1>4. Creating and Editing Files in CHTC</h1>

<p>Once you have logged in to a CHTC server, you can edit files from 
the command line, by using a command line file editor. Some 
common editing programs are:</p>
<ul>
<li>nano</li>
<li>vi</li>
<li>emacs</li>
</ul>

<p><code>nano</code> is the most beginner-friendly, and <code>emacs</code> is the 
most advanced.  <a href="http://swcarpentry.github.io/shell-novice/03-create/">This
Software Carpentry lesson</a> describes how to use <code>nano</code>, and there are 
many other resources online with instructions for these text editors.  </p>

<p>Some of the file transfer programs mentioned <a href="#transfer-winscp">above</a>
allow you to edit files on CHTC servers through the interface.</p>

<a name="learn"></a>
<h1>5. Learning About the Command Line</h1>

<p><b>Why learn about the command line?</b>
If you haven't used the command line before, it might seem like a big 
challenge to get started, and easier to use other tools, especially if 
you have a Windows computer.  However, we strongly recommend learning more 
about the command line for multiple reasons: </p>
<ul>
  <li>You can do most of what you need to do in CHTC by learning a few basic commands.</li>
  <li>With a little practice, typing on the command line is significantly faster 
  and much more powerful than using a point-and-click graphic interface.</li>
  <li>Command line skills are useful for more than just large-scale computing.</li>
</ul>

<p>For a good overview of command line tools, see the
<a href="http://swcarpentry.github.io/shell-novice/">Software Carpentry
Unix Shell</a> lesson.  In particular, we recommend the sections on: </p>

<ul>
<li>understanding the filesystem and how to navigate it 
(<a href="http://swcarpentry.github.io/shell-novice/02-filedir/">Navigating Files and Directories</a>)</li>
<li>tab-completion 
(section entitled "Nelle's Pipeline, Organizing Files", in <a href="http://swcarpentry.github.io/shell-novice/02-filedir/">Navigating Files and Directories</a>)</li>
<li>creating files (<a href="http://swcarpentry.github.io/shell-novice/03-create/">Working With Files and Directories</a>)</li>
<li>using the star wildcard (first part of 
<a href="http://swcarpentry.github.io/shell-novice/04-pipefilter/">Pipes and Filters</a>)</li>
<li>writing shell scripts (<a href="http://swcarpentry.github.io/shell-novice/06-script/">Shell Scripts</a>) </li>
</ul>