From df1acfc8b82000ab009a128727affa1b93f22081 Mon Sep 17 00:00:00 2001 From: Expo on server Date: Mon, 3 Jul 2023 03:14:31 +0100 Subject: [PATCH] Update IP addresses to reflect fact that tattyhut network is 192.168.200.x - online edit of handbook/computing/netconfig.html --- handbook/computing/netconfig.html | 23 ++++++++++++----------- 1 file changed, 12 insertions(+), 11 deletions(-) diff --git a/handbook/computing/netconfig.html b/handbook/computing/netconfig.html index d2c9f58a8..5620d2a45 100644 --- a/handbook/computing/netconfig.html +++ b/handbook/computing/netconfig.html @@ -38,7 +38,7 @@ still upright and have not been knocked sideways.

The potato hut wifi

The potato hut wiFi has SSID "tattyhut" with our usual cavey:beery password. Like almost every other wifi anywhere it is running DHCP and allocating IP addresses to your device. -

The DHCP system is issuing IP4 addresses of the form 192.168.1.x where x is a number between 11 and 199 with a lifetime of 48 hours. +

The DHCP system is issuing IP4 addresses of the form 192.168.200.x where x is a number between 11 and 199 with a lifetime of 48 hours.

The Expo laptops acquire a dynamic local address of this form, as does any other laptop or phone connecting to this wifi.

How it works - in words

@@ -51,7 +51,7 @@ Ignore the backup copy in /home/expo/fakenet.

Wifi/router Netgear WNDR4000

The Netgear ethernet/wifi hub holds the radio transceiver that provides the wifi coverage inside the potato hut. It has an online manual but it needs no configuration at all during expo. Just turn it on at the beginning of expo and off again at the end. -

The webpage control panel (which you should never need or touch) is accessed by connecting a laptop to the wifi or using the expo laptop on the ethernet and bringing up a web browser to http://192.168.1.1 with username 'admin' and the usual expo cavey:beery password. The password is also written on the underneath of the box. +

The webpage control panel (which you should never need or touch) is accessed by connecting a laptop to the wifi or using the expo laptop on the ethernet and bringing up a web browser to http://192.168.200.1 with username 'admin' and the usual expo cavey:beery password. The password is also written on the underneath of the box.

TL-WR841N
@@ -59,7 +59,7 @@ Ignore the backup copy in /home/expo/fakenet.
TL-WR841N sockets and switches
-

In 2023 we will also have a backup wifi/router in Austria, a £20 TL-WR841N 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. +

In 2023 we will also have a backup wifi/router in Austria, a TL-WR841N 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.

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.

Alfa wifi device

@@ -73,18 +73,18 @@ Ignore the backup copy in /home/expo/fakenet.

To understand how the network is configured, you need to realise that we have to manage these different 'networks':

-We bridge the hut wifi with the hut ethernet cable to the expo laptop so they are both 192.168.1.x, but this is a matter of choice. This is configured inside the wifi/router using the webpage control panel. +We bridge the hut wifi with the hut ethernet cable to the expo laptop so they are both 192.168.200.x, but this is a matter of choice. This is configured inside the wifi/router using the webpage control panel.

Where the DNS happens

DNS is what connects a computer name (such as expo.survex.com) with an internet address (such as 78.129.164.125). 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.

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.

Where the DHCP happens

-

DHCP is what decides what the x is when the wifi issues an address that a laptop must use when it connects to the wifi as 192.168.1.x. +

DHCP is what decides what the x is when the wifi issues an address that a laptop must use when it connects to the wifi as 192.168.200.x.

We have done this in two different ways:

  1. 2017-2019 : in the netbook. @@ -92,7 +92,8 @@ We bridge the hut wifi with the hut ethernet cable to the expo laptop

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.

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 and a web interface. Also, by making the Netgear box completely dumb, it is swap-replaceable if it dies with no reconfiguration required. -

The DHCP is configured to issue IP addresses with x between 10 and 199, i.e. laptops and phones will get IP addresses between 192.168.1.10 and 192.168.1.199. These may change after 12 hours. +

The DHCP is configured to issue IP addresses with x between 10 and 199, i.e. laptops and phones will get IP addresses between 192.168.200.10 and 192.168.200.199. These may change after 12 hours. +

The router itself is 192.168.200.1

Interfaces

@@ -100,9 +101,9 @@ We bridge the hut wifi with the hut ethernet cable to the expo laptop

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 10.0.1.2. wlan0 on the netbook is the internal wifi. -

The Netgear box has its yellow ethernet cable socket set to the address 10.0.1.1. The four other ethernet sockets are all on the address range 192.168.1.x and the wifi network interface is set to 192.168.1.1 also in the network 192.168.1.x. +

The Netgear box has its yellow ethernet cable socket set to the address 10.0.1.1. The four other ethernet sockets are all on the address range 192.168.200.x and the wifi network interface is set to 192.168.200.1 also in the network 192.168.200.x. -

So the ethernet cable between the Netgear box and the netbook is 10.0.1.1 at the Netgear end and 10.0.1.2 at the netbook end. Nothing else uses any number like 10.0.x.y. +

So the ethernet cable between the Netgear box and the netbook is 10.0.1.1 at the Netgear end and 10.0.1.2 at the netbook end. Nothing else uses any number like 10.0.1.x.

When it all goes wrong

@@ -387,7 +388,7 @@ the Gasthof. We continued with the wifi service in the hut but now it also conne

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.

History of the scripts

-

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.] +

The structure of the system was created by Wookey in 2013 who used the fakenet principle and the netbook to run training sessions in caving huts with no internet connection for the Cave Survey Group in the UK. [This is why the script has an extra level of parameter setting that might seem unnecessary: it has 'csg' and 'expo' options, but the two configurations have diverged so much over the years that this is merely a fossil.]

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.