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317 lines
21 KiB
HTML
317 lines
21 KiB
HTML
<!DOCTYPE html>
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<html>
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<head>
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<title>CUCC Expedition Handbook: Hut network</title>
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<link rel="stylesheet" type="text/css" href="../css/main2.css" />
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</head>
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<body>
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<h2 id="tophead">CUCC Expedition Handbook</h2>
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<h1>Hut Network Configuration</h1>
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<div align=center>
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<p>If the internet is not working, the <b>first thing to check</b> is that<br>the black WiFi antennae are
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still upright and have not been knocked sideways.
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</div>
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<br>
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<h2>Networking Software - configuration nerding</h2>
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<p>First, make sure you understand the physical cabling:
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<figure align=center >
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<a href="../l/hut-cables.html"><img border=1 src="../t/hut-cables-small.jpg"></a>
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<br><figcaption>Hut Network - click for instructions</figcaption>
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</figure>
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<h3>Expo laptops</h3>
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<p>Both expo laptops Crowley and Aziraphale use DHCP to get an IP4 address and the identity of a DNS nameserver. Neither laptop has any other configuration.
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<p>If you connect your laptop or phone to the potato hut wifi you will connect in the same way.
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<h3>The Gasthof Wifi</h3>
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<p>The Gasthof WiFi - which you can use if you are close enough to the main building - is "StaudnGast" and has no WiFi password but there is a login webpage. It allocates IP addresses in the range <samp>192.168.2.x</samp> etc. The antenna is now on the first-floor balcony within sight of the tatty hut window. You can get the password from the Gasthof front desk, or during expo it is usally written on the whiteboard in the potato hut. In the scripts published in this handbook we use the word GASTSECRET instead of the real password.
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<p>If you are not actively using the internet, the Gasthof system will close the connection after a few minutes and you will have to re-login again, typing the password into the login page.
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<h3>The potato hut wifi</h3>
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<p>The potato hut wiFi has <a href="https://www.howtogeek.com/334935/what-is-an-ssid-or-service-set-identifier/">SSID</a> "tattyhut" with our usual cavey:beery password. Like almost every other wifi anywhere it is running DHCP and allocating IP addresses to your device.
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<p>The DHCP system is issuing IP4 addresses of the form <samp>192.168.1.x</samp> where x is a number between 11 and 199 with a lifetime of 48 hours.
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<p>The <em>Expo laptops</em> acquire a dynamic local address of this form, as does any other laptop or phone connecting to this wifi.
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<h3>How it works - in words</h3>
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<p>The <a href="https://en.wikipedia.org/wiki/Acer_Aspire_One">Acer Aspire One</a> netbook is running Debian Linux operating system with the lightweight <a href="https://xfce.org/">[xfce]</a> window mananger. It runs a script once every 60s which checks whether it can access the internet. If it can't, it attempts a re-login to the Gasthof wifi system, which takes 5-10 seconds. If it still can't access the internet it deletes nearly all the configuration and reloads everything - which takes about 30s. The mere fact that it accesses the internet every minute is enough for the Gasthof system to keep the connection open - until it times out completely which it does after an hour or so.
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<p>Because of a permissions difficulty, the scripts on the netbook live in <var>/root/fakenet</var> so that the cron job (running as root) can access them. [This is not the usual Linux place to keep such things.] The cron file lives in the usual place in <var>/etc/cron/cron.d/fakenet</var>.
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<p>When the netbook powers up, the script <var>/etc/init.d/fakenet</var> runs which sets everything going for the first time.
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<h4>Wifi/router Netgear WNDR4000</h4>
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<p>The Netgear ethernet/wifi hub holds the radio transceiver that provides the wifi coverage inside the potato hut.
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It has an <a href="https://manualmachine.com/netgear/wndr4000/816208-user-manual/">online manual</a> but it needs no configuration at all during expo. Just turn it on at the beginning of expo and off again at the end.
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<p>The webpage control panel (which you should never need or touch) is accessed by connecting a laptop to the wifi or using the <var>expo laptop</var> on the ethernet and bringing up a web browser to <a href="http://192.168.1.1">http://192.168.1.1</a> with username 'admin' and the usual expo cavey:beery password. The password is also written on the underneath of the box.
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<h5>TL-WR841N</h5>
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<figure class="onright" >
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<a href="WR841N.jpg"><img border=1 src="WR841N.jpg"></a>
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<br><figcaption>TL-WR841N sockets and switches</figcaption>
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</figure>
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<p>In 2023 we will also have a backup wifi/router in Austria, a £20 <a href="https://www.expertreviews.co.uk/tp-link/1401766/tp-link-tl-wr841n-review">TL-WR841N</a> belonging to Wookey which is configured identically to the Netgear device except that the username is 'root' not 'admin'. It is to be used only if the Netgear breaks.
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<p>One important difference is that the ethernet cable from the netbook is plugged into the blue socket on the WR841N (it is yellow on the Netgear), and the 4 white sockets on the Netgear are 4 yellow sockets on the WR841N. A word of warning: the WR841N has been flashed with new firmware and so any documentation you may read in online manuals for it will be wrong: notably the reset and wifi on/off buttons don't have any effect, and the lights don't flash in the way the manuals say they do. There is also no USB socket, no IP6, no 5Ghz, slower ethernet (100Mbps not 1Gbps) and the wifi range out to the tents is worse than the Netgear wifi.
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<h4>IP6</h4>
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<p>While you can use 5Ghz wifi and IP6 to connect within the hut, there is no IP6 connectivity to the external internet. Sorry. We are dependent on the Gasthof system for this. Use a phone and data roaming if you want it.
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<h3>4 different 'networks'</h3>
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<p>To understand how the network is configured, you need to realise that we have to manage these different 'networks':
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<ul>
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<li><samp>192.168.2.x</samp> The Gasthof wifi network
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<li><samp>192.168.1.x</samp> The potato hut wifi network
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<li><samp>10.0.x.y</samp> The network on the short bit of cable connecting the netbook with the Netgear box.
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<li>The network on the longer length of cable connecting the Netgear box with the <var>expo laptop</var> (and sometimes the printer).
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</ul>
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We bridge the hut wifi with the hut ethernet cable to the <var>expo laptop</var> so they are both <samp>192.168.1.x</samp>, but this is a matter of choice. This is configured inside the wifi/router using the webpage control panel.
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<h4>Where the DNS happens</h4>
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<p> DNS is what connects a computer name (such as <var>expo.survex.com</var>) with an internet address (such as <samp>78.129.164.125</samp>). To make the internet work, we need to tell every laptop and phone where to find a DNS nameserver, or what machine to ask in order to get DNS queries forwarded to a DNS nameserver.
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<p>The DNS configuration happens in the netbook. The Netgear box just forwards DNS queries to the netbook, and tells laptops connected to the hut wifi to use that too.
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<h4>Where the DHCP happens</h4>
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<p>DHCP is what decides what the <samp>x</samp> is when the wifi issues an address that a laptop must use when it connects to the wifi as <samp>192.168.1.x</samp>.
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<p>We have done this in two different ways:
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<ol>
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<li>2017-2019 : in the netbook.
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<li>2022 : in the Netgear box.
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</ol>
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<p>1. The benefit of doing it in the Netgear box is that you get to play with a graphical web interface not text files. But also you can test that the Netgear box is working separately from everything else.
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<p>2. The benefit of doing it in the netbook is that all the configuration is in the same place, and you only have to learn one way of doing things instead of having to use text files <em>and</em> a web interface. Also, by making the Netgear box completely dumb, it is swap-replaceable if it dies with no reconfiguration required.
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<p>The DHCP is configured to issue IP addresses with <samp>x</samp> between 10 and 199, i.e. laptops and phones will get IP addresses between <samp>192.168.1.10</samp> and <samp>192.168.1.199</samp>. These may change after 12 hours.
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<h4>Static addresses</h4>
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<p>The netbook has two network interfaces: the Alfa wifi antenna (which has an address issued by the Gasthof wifi system) plugged into a USB socket, and the netbook's ethernet cable socket which is configured to have the address <samp>10.0.1.2</samp>.
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<p>The Netgear box has its yellow ethernet cable socket set to the address <samp>10.0.1.1</samp>. The four other ethernet sockets are all on the address range <samp>192.168.1.x</samp> and the wifi network interface is set to <samp>192.168.1.1</samp> also in the network <samp>192.168.1.x</samp>.
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<p>So the ethernet cable between the Netgear box and the netbook is <samp>10.0.1.1</samp> at the Netgear end and <samp>10.0.1.2</samp> at the netbook end. Nothing else uses any number like <samp>10.0.x.y</samp>.
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<h4 style="color: red">When it all goes wrong</h4>
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<p>If everything is working between devices in the hut, but there is no internet access, then the <b>first thing to check</b> is that
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the black WiFi antennae on the small black Alfa box are still upright and have not been knocked sideways.
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<p>The next thing is to take a phone out to the road and try to connect directly to the Gasthof wifi. This is to check that the Gasthof is on the internet and that the problem is not between the Gasthof and the rest of the world.
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<p>You test whether the internet is running by trying to visit <a href="http://www.google.com">www.google.com</a> or
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<a href="https://github.com">github.com</a>.
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<p>The netbook attempts a reconnection every 60 seconds, so wait at least 2 minutes before doing anything. That is because when the netbook attempts a full reconnection it can take nearly a minute to rebuild everything.
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<p>Test whether the netbook is actually running and responding by sitting at the <var>expo laptop</var> and logging into the netbook remotely. Do this in a terminal window:
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<pre><code>ssh expo@tclaspire3.potato.hut</code></pre>
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or
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<pre><code>ssh expo@tclaspire3.hut</code></pre>
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or
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<pre><code>ssh expo@10.0.1.2</code></pre>
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(The last of these may not actually work: this is a non-routable IP address.)
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<p>If you get a login prompt, the netbook is running. It is a slow machine so do not expect this to be instant.
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<p>Login to the netbook (as user 'expo' using the cavey:beery password) and type this at a prompt:
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<pre><code>/root/fakenet/runfakenet</code></pre>
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which will run the script to reconnect. This may take a minute to have the desired effect.
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<p>If you didn't get a prompt when you attempted to login from the <var>expo laptop</var> then you will need to do the same thing but actually on the netbook keyboard. While you are at it, it would be a good idea to re-boot the netbook first by typing this on the netbook keyboard first, and waiting for it to re-boot:
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<pre><code>shutdown --reboot</code></pre>
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<p>You may also need to re-enable wicd, see below.
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<p>If it keeps failing, then maybe the <var>cron</var> system which re-triggers it every 60s is not working. That is probably a symptom of something more much more serious wrong with the netbook if you have already re-booted it. Try re-booting it again and this time be more patient. <em>Report this</em> to a nerd, <em>write a record of the problem in the expo logbook</em> and <em><a href="https://app.element.io/#/room/#LoserExpoWebsite:matrix.org">post a request for help</a></em> to the expo Matrix chat system.
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<h4>wicd</h4>
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<p>The netbook needs to have its persistent networking set up correctly <i>in addition to the other scripts</i>. This
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is the <a href="https://launchpad.net/wicd">wicd</a> gui program that has an icon in the top-right of the sceen in the
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system panel. (Or search in all applications in the Internet section for the <var>wicd</var> application). Set the checkboxes so
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that the netbook does not connect to any network except the StaudnGast wifi network, and also tick the 'automatically
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reconnect' checkbox for the "StaudnGast" network.
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<h2 id="scripts">The scripts</h2>
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<p>For the curious or desperate, here is how the scripts actually work.
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<p>The master copy of the scripts in on the expo server in <var>/home/expo/config/netbook</var> which includes the files
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<ul>
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<li><a href="netbookfakenet/readme">readme</a>
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<li><a href="netbookfakenet/fakenetcron">fakenetcron</a> - needs to be renamed and copied to <var>/etc/cron.d/fakenet</var>
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<li><a href="netbookfakenet/70-persistent-net.rules">70-persistent-net.rules</a> - needs to be copied into <var>/etc/udev/rules.d/</var>
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<li>fakenet2022.tgz - needs to be unpacked into <var>/root</var>
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</ul>
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<p>The files linked in this documentation are sanitized copies, not the master files. Get the master files by ftp or scp from <var>expo.survex.com/home/expo/config/netbook</var>.
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<p>Installation instructions are in the <a href="netbookfakenet/readme">readme</a> file. These are all documented below, but do get an updated copy from <var>expo.survex.com/home/expo/config/netbook</var> before you do anything.
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<h3>After installation of the files</h3>
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<p>The central script is <a href="netbookfakenet/fakenet2022/keepalive">/root/fakenet/keepalive</a> which is run every 60 seconds:
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<pre><code>
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#!/bin/sh
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# Runs from cron
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if ( ping -c 1 -w 5 -q wookware.org ); then
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#working
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:
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else
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#rerun login
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/root/fakenet/expo/gasthoflogin
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sleep 10
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if ( ping -c 1 -w 5 -q wookware.org ); then
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#working now
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:
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else
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#re-setup full network config
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/root/fakenet/runfakenet
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fi
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fi
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</code></pre>
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As you can see, it checks if the internet is available by looking for <var>wookware.org</var> and if not, it runs the Gasthof login script. If there is still no joy, it runs the full network reconfiguration script.
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<p>Gasthof login script <a href="netbookfakenet/fakenet2022/expo/gasthoflogin">/root/fakenet/expo/gasthoflogin</a>:
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<pre><code>#!/bin/bash
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#Script to connect to gasthof wifi
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#Pull random webpage to get login page
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# DNS must point to gasthof network, request must be by name
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# Resolves, then HTTP request gets 303 'See Other'
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#Extract magic token, then send login+token to 192.168.2.1:1000/fgtauth?<token>
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# Do it in a tmp dir to stop collecting index.html's
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tmp=$(mktemp -d)
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cd $tmp
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echo "nameserver 213.33.99.70" > /etc/resolv.conf
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wget http://wookware.org/
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magic=$(cat index.html | tail -1 | sed 's/^.*magic" value="//' | sed 's/".*//')
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wget -o /dev/null --post-data="username=Gast&password=GASTSECRET&magic=$magic" http://192.168.2.1:1000/
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rm -f index.html
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rm -f index.html.*
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cd ..
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rmdir $tmp
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</code></pre>
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As you can see, it attempts to get http://wookware.org/index.html but actually gets the gasthof login form, which it then POSTs to with the Gasthof password - which is not actually GASTSECRET. Get this year's Gasthof password from the reception desk and write it on the whiteboard in the hut.
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<p>Network rebuild script <a href="netbookfakenet/fakenet2022/runfakenet">/root/fakenet/runfakenet</a> where ${base} is "/root/fakenet" and ${config} is "expo" as set in <a href="netbookfakenet/fakenet2022/config">/root/fakenet/config</a>. (This config is a relic from the CSG script in 2014, see Historical Notes below.)
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<pre><code>#!/bin/sh -eux
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. /root/fakenet/config
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#Close down running interfaces and services
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sudo ifdown -i ${base}/${config}/netconfig eth0
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sudo ifdown -i ${base}/${config}/netconfig wlan0
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sudo ifdown -i ${base}/${config}/netconfig wlan1
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sudo service wicd stop
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sudo iptables -F
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sudo killall dhclient || true
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sudo /etc/init.d/dnsmasq stop
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sudo killall dnsmasq || true
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#Now bring up desired networking
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#ethernet to router
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sudo ifup -i ${base}/${config}/netconfig eth0
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#wlan1 long-range wireless to gasthof
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sudo ifup -i ${base}/${config}/netconfig wlan1
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#Set up hostapd for local wireless - not currently (2022) used
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#sudo service hostapd restart
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#Make this machine do DNS for potatohut
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#And forward external requests to the real net
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sudo dnsmasq -q -C ${base}/${config}/dnsmasq.conf
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#bridge/masquerade from gasthof to router
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${base}/${config}/masquerade
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# Log in to Gasthof wifi!
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${base}/${config}/gasthoflogin
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# Join Acer to potatohut network for admin purposes
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#sudo ifup -i ${base}/${config}/netconfig wlan0
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</code></pre>
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<h4>Other vital configuration bits</h4>
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<p>The <var>/root/fakenet/expo/hosts</var> file is just two lines:
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<pre><code>10.0.1.2 tclapsire3
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10.0.1.1 router
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</code></pre>
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<p>The file that configures the wifi is the file <var>/root/fakent/expo/hostapd.conf</var>
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<pre><code>interface=wlan0
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driver=nl80211
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ssid=tattyhut
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hw_mode=g
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channel=1
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macaddr_acl=0
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ignore_broadcast_ssid=0
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auth_algs=1
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wpa=3
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wpa_passphrase=CAVEYBEERYPASSWORD
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wpa_key_mgmt=WPA-PSK
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wpa_pairwise=TKIP
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rsn_pairwise=CCMP
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</code></pre>
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where CAVEYBEERYPASSWORD is our usual expo password. In 2022 this capability was configured by the Netgear control panel, not by this file on the netbook.
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<p>The file that configures the DNS and DHCP is <var>/root/fakent/expo/dnamasq.conf</var> and it is very long with
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most of the lines commented out with an initial '#', so they are not all listed here. (You can read a copy of it <a
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href="copy-of-dnsmasq.conf">here</a>). On the netbook 'eth0' is the interface with the antenna (which is actually a
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USB socket) and 'wlan0' is the ethernet socket interface to the cable to the Netgear box. Some of the more relevant
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lines are:
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<pre><code>interface=wlan0
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dhcp-range=192.168.1.10,192.168.1.199,12h
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addn-hosts=/root/fakenet/expo/hosts
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expand-hosts
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domain=potato.hut
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no-dhcp-interface=eth0
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</code></pre>
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Note the line <var>addn-hosts=/root/fakenet/expo/hosts</var> which refers to the first file listed above which defines the names of the machines for the two ends of the cable between the netbook and the Netgear box.
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<p>The cron job file that configures <var>crontab</var> to run the fakenet script every 60 seconds is
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<a href="netbookfakenet/70-persistent-net.rules">70-persistent-net.rules</a>. It is a single line of cron configuraiton:
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<pre><code>*/1 * * * * root [ -x /root/fakenet/keepalive ] && /root/fakenet/keepalive
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</code></pre>
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where the initial <samp>*/1 * * * *</samp> means that it runs once a minute, on every hour, day, month and year.
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<p> The init script which configures everything when the netbook is booted up is
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<pre><code>MISSING
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MISSING - need to get this...
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</code></pre>
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<h2>Buggeration - how it will all go wrong..</h2>
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<p>We are using an old way of configuring network interfaces in debian. Which will all break at some point when
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someone does a debian upgrade. The scripts use the <a href="https://wiki.debian.org/NetworkInterfaceNames">
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"Predicatable Names" scheme</a> and <a href="https://wiki.debian.org/iptables">iptables</a> which are both earmarked for destruction.
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<h2>Historical Notes</h2>
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<p>Prior to 2017 we used to run an unconnected local network with our own DNS domain
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name "potato.hut", our own server holding all the website and survey data, and published WiFi as SSID "tattyhut".
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Updates to the rest of the world were done by taking an up-to-date laptop which had been in
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the tatty hut to a real internet connection and
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pushing the changes to the distributed version control system on
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<span style="font-family:monospace">expo.survex.com</span> to be merged.
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</p>
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<p>In 2017 we arrived on expo to discover that our hard-drive in the hut had died (taking the music collection with it) which triggered the general reconfiguration to connect the tattyhut to
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the internet continuously and not to have our own local server. This coincided with a much-improved WiFi service at
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the Gasthof. We continued with the wifi service in the hut but now it also connects to the external internet instead of to a 'pretend' internet (which is why the system is called 'fakenet').
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<p>In 2018 and 2019 we had good Internet access at basecamp, but the high-gain system (old Alfa) was returned to its owner (Sam) during Covid (2020-21). Wookey bought a new one, which proved to not live up to its advertising.
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<p>In 2022 Wifi reception from the Gasthof was very poor. The connection script was improved so that dropped connections were restored more quickly. However the basic bandwidth with the new cheap antenna was not enough.
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<p>In 2023 a new Wifi device (the new Alfa) should restore decent connectivity. We hope this will improve everything to how it was in 2019. However this new Alfa has proved to be a right bastard to find the right drivers for. Wookey has had to be inventive in using an Ubuntu PPA to make it work with the Acer Aspire 1.
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<p>Also during winter 2023/23 Wookey upgraded the operating system on the Acer Aspire One netbook from the ancient Debian Wheezy it had been running to a decently almost-modern Debian distribution. This required much coaxing.
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<h4>History of the scripts</h4>
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<p>The structure of the system was created by Wookey in 2013 who used the fakenet principle and the netbook to run training sessions for the Cave Survey Group in the UK. [This is why the script has an extra level of parameter setting that might seem necessary: it has 'csg' and 'expo' options, but the two configurations have diverged so much over the years that this is merely a fossil.]
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<p>The part of the script that logs into the Gasthof wifi was written by Mark Shinwell in 2017 and re-edited by Sam Wenham in 2019. Wookey made it more robust on expo in 2022.
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Go back to
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<a href="../l/hut-cables.html">Hut cabling</a><br />
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Go back to: <a href="computer.html">Basecamp computers</a><br />
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Go on to: <a href="onlinesystems.html">Expo online systems</a><br />
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