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Update/clarify some network config details (Wookey) - online edit of handbook/computing/netconfig.html

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Expo on server 2023-06-30 03:11:44 +01:00
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handbook/computing/netconfig.html
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@ -44,8 +44,8 @@ still upright and have not been knocked sideways.
<h3>How it works - in words</h3>
<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.
<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>.
<p>The <str>used</str> scripts on the netbook live in <var>/root/fakenet</var> so that the cron job (running as root) can access them and things work even if /home is not monted. [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>.
Ignore the backup copy in /home/expo/fakenet.
<p>When the netbook powers up, the script <var>/etc/init.d/fakenet</var> runs which sets everything going for the first time.
<h4>Wifi/router Netgear WNDR4000</h4>
@ -59,8 +59,8 @@ still upright and have not been knocked sideways.
<br><figcaption>TL-WR841N sockets and switches</figcaption>
</figure>
<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.
<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.
<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 would be good to test this so we could give ARM their WNDR4000 back, and the TP-link router can become expo's.
<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 (openWRT) 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 5Ghz, slower ethernet (100Mbps not 1Gbps) and the wifi range out to the tents is probably worse than the Netgear wifi.
<h4>IP6</h4>
<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.
@ -77,7 +77,7 @@ We bridge the hut wifi with the hut ethernet cable to the <var>expo laptop</var>
<h4>Where the DNS happens</h4>
<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.
<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.
<p>The DNS configuration happens in the netbook, using dnsmasq. The Netgear box just forwards DNS queries to the netbook, and tells laptops connected to the hut wifi to use that too.
<h4>Where the DHCP happens</h4>
<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>.
@ -90,14 +90,17 @@ We bridge the hut wifi with the hut ethernet cable to the <var>expo laptop</var>
<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.
<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.
<h4>Static addresses</h4>
<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>.
<h4>Interfaces</h4>
<p>The netbook has two network interfaces: the Alfa wifi antenna (which is 'wlan1' and has an address issued by the Gasthof wifi system using DHCP) plugged into a USB socket, and the netbook's ethernet cable socket (eth0) which is configured to have the address <samp>10.0.1.2</samp>.
wlan0 on the netbook is the internal wifi.
<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>.
<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>.
<h4 style="color: red">When it all goes wrong</h4>
<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
the black WiFi antennae on the small black Alfa box are still upright and have not been knocked sideways.