CERN Computer Security Information

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /> <link rel="stylesheet" href="/style.css" type="text/css" /> <script type="text/javascript" src="/jquery.min.js"></script> <title>CERN Computer Security Information</title> <script type="text/javascript"> $(document).ready(function(){ // Menu highlight var path = location.pathname.split("/"); if ( path ) { $('#main_menu a[href*="' + path[1] + '"][class!="noselect"]').addClass('selected'); // path[3] = /security/<xxxxx>/ $('#sidebar ul.sidemenu li[class!="noselect"]:has(a[href$="' + path.reverse()[0] + '"])').addClass('selected'); } // Add icon to external links $('a[id!=logo-img]').filter(function() { return this.hostname && this.hostname !== location.hostname; }).after(' <img src="/images/external_link.png" alt="external link" title="external link"/>'); }); </script> </head> <body> <div id="wrap"> <div id="top-bg"></div>  <div id="header"> <div id="logo-text"> <a id="logo-img" href="https://home.cern/"><img src="/images/CERNLogo2.png" width="59" height="59" style="margin: 10px" alt="CERN Logo"/></a><div id="logo-text-big"><a href="/home/en/index.shtml" title="">CERN Computer Security</a></div> </div> <div id="header-logo"><a href="/services/en/emergency.shtml"><img width=335 src="/images/emergency.png" alt="Computer Emergencies"/></a></div> </div>  <div id="header-photo"></div>  <div id="nav"> <ul id="main_menu"> <li><a class="noselect" href="/home/fr/index.shtml"><img src="/images/fr.png" alt="FR"/></a></li> <li><a href="/home/en/index.shtml">Home</a></li> <li><a href="/rules/en/index.shtml">Computing Rules</a></li> <li><a href="/recommendations/en/index.shtml">Recommendations</a></li> <li><a href="/training/en/index.shtml">Training</a></li> <li><a href="/services/en/index.shtml">Services</a></li> <li><a class="secured" href="/reports/en/index.shtml">Reports & Presentations</a></li> </ul> </div>   <div id="content-wrap"> <div id="main"> <h2 id="Advance-access">SSH Tunneling</h2> <p>If your application does not support socks proxies or you need a different access to the CERN network you need to tunnel via ssh. This solution exists only for Linux and macOS. There are currently no tested methods for Windows available.</p> <h4>ProxyJump</h4> <p>Setup your <tt>.ssh/config</tt> for using a jump host:</p> <pre><code>Host *.cern.ch !lxplus.cern.ch !aiadm.cern.ch !lxplus !aiadm !gitlab.cern.ch !lxtunnel.cern.ch !lxtunnel User YOURCERNUSER ProxyJump lxtunnel.cern.ch Host lxplus.cern.ch aiadm.cern.ch lxtunnel.cern.ch lxtunnel lxplus aiadm User YOURCERNUSER # if your client is configured for Kerberos GSSAPIDelegateCredentials yes GSSAPIAuthentication yes GSSAPITrustDns yes </code></pre> <p>Note: macOS does not support <tt>GSSAPITrustDns</tt>. You need to remove this line on MacOS.</p> <h4 id="SingleHost">Jumping to a single host</h4> <p>If you want to access a single host (e.g. to connect with VNC to it) you can run: <code> $ ssh -L 5900:target-server.cern.ch:5900 <USER>@lxtunnel.cern.ch </code> and then you can connect to the server (e.g. with xvncviewer): <code> $ xvncviewer localhost </code> </p> <h4 id="sshuttle">sshuttle</h4> <p><a href="https://github.com/sshuttle/sshuttle" target="_blank" rel="noopener">sshuttle</a> is a “poor man’s VPN” solution which works on macOS and Linux. It uses SSH tunneling to transparently redirect certain parts of your traffic to the internal network.</p> <p>For Linux and macOS you can use the following command:</p> <pre><code>sshuttle --dns -vr <USER>@lxtunnel.cern.ch 137.138.0.0/16 128.141.0.0/16 128.142.0.0/16 188.184.0.0/15 --python=python </code></pre> <p>This command routes the traffic to CERN IPs through a tunnel. On Linux this only works for IPv4 addresses. For IPv6 you need to set <tt>--method=tproxy</tt>. This method requires root privileges and is not tested. On macOS you can add <tt>2001:1458::/32 2001:1459::/32</tt> to also tunnel IPv6 through.</p> <p>It is possible to let sshuttle run as a daemon. This script can help with this:</p> <pre><code>#!/bin/sh case $1 in connect) sshuttle --dns -vr <USER>@lxtunnel.cern.ch 137.138.0.0/16 128.141.0.0/16 128.142.0.0/16 188.184.0.0/15 --daemon --pidfile /tmp/sshuttle.pid --python=python shift ;; disconnect) kill `cat /tmp/sshuttle.pid` shift ;; status) echo "IP address as seen by CERN servers: " `wget -O - -q "https://security.web.cern.ch/ip.php"` echo "IP address as seen by external sites: " `wget -O - -q "https://api.my-ip.io/ip"` shift ;; *) # unknown option ;; esac </code></pre> </div>    <div id="sidebar"> <h3>For All Users<br/> (Experts or Not)</h3> <ul class="sidemenu"> <li><a href="/recommendations/en/good_practises.shtml">Seven easy good practises</a></li> <li><a href="/recommendations/en/how_to_secure_your_pc.shtml">How to secure your PC or Mac</a></li> <li><a href="/recommendations/en/passwords.shtml">Passwords & toothbrushes</a></li> <li><a href="/recommendations/en/2FA.shtml">Starting with multi-factor authentication</a></li> <li><a href="/recommendations/en/bad_mails.shtml">Bad mails for you:<br/>"Phishing", "SPAM" & fraud</a></li> <li><a href="/recommendations/en/malicious_email.shtml">How to identify malicious e-mails and attachments</a></li> <li><a href="/recommendations/en/how_to_remove_malicious_browser_notifications.shtml">How to remove malicious browser notifications</a></li> <li><a href="/recommendations/en/working_remotely.shtml">Working remotely</a></li> <li><a href="/recommendations/en/connecting_to_cern.shtml">Connecting to CERN</a></li> <li><a href="/recommendations/en/ssh.shtml">Connecting using SSH</a></li> </ul> <h3>For Software Developers</h3> <ul class="sidemenu"> <li>Good programming in <a href="/recommendations/en/program_c.shtml">C/C++</a>, <a href="/recommendations/en/program_java.shtml">Java</a>, <a href="/recommendations/en/program_perl.shtml">Perl</a>, <a href="/recommendations/en/program_php.shtml">PHP</a>, and <a href="/recommendations/en/program_python.shtml">Python</a></li> <li><a href="/recommendations/en/password_alternatives.shtml">How to keep secrets secret<br/> (alternatives to passwords)</a></li> <li><a href="/recommendations/en/checklist_for_coders.shtml">Security checklist</a></li> <li><a href="https://gitlab.docs.cern.ch/docs/Secure%20your%20application/">GitLab CI Security Tools</a></li> <li><a href="/recommendations/en/web_applications.shtml">Securing Web applications</a></li> <li><a href="/recommendations/en/code_tools.shtml">Static code analysis tools</a></li> <li><a href="/recommendations/en/more_on_software.shtml">Further reading</a></li> </ul> <h3>For System Owners</h3> <ul class="sidemenu"> <li><a href="/recommendations/en/rootkits.shtml">Checking for rootkits</a></li> <li><a href="https://twiki.cern.ch/twiki/bin/viewauth/CNIC/WebHome">Securing Control Systems (CNIC)</a></li> <li><a href="/recommendations/en/containers.shtml">Securing Containers & Pods</a></li> <li><a href="/rules/en/baselines.shtml">Security baselines</a></li> <li><a href="http://linux.web.cern.ch/linux/docs/linux_exploit_faq.shtml"> The CERN Linux vulnerability FAQ</a></li> </ul> </div>   </div>  <div id="footer-wrap"> <div id="footer-bottom"> © Copyright 2024<strong> <a href="https://cern.ch/security">CERN Computer Security Office</a></strong> <table> <tr> <td id="footer-info-left"> e-mail: <a href="mailto:Computer.Security@cern.ch">Computer.Security@cern.ch</a><br/> Please use the following PGP key to encrypt your messages:<br/> ID: 0x954CE234B4C6ED84<br/> <a href="https://keys.openpgp.org/vks/v1/by-fingerprint/429D60460EBE8006B04CDF02954CE234B4C6ED84">429D 6046 0EBE 8006 B04C DF02 954C E234 B4C6 ED84</a> </td> <td id="footer-info-right"> Phone: +41 22 767 0500<br/> Please listen to the recorded instructions. </td> </tr> </table> </div> </div>  </div>   </body> </html>

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CERN Computer Security Information