Installing OpenVPN

Based on OpenVPN 2.4.0. On a Raspberry Pi...

   sudo apt-get install openvpn openssl easy-rsa

   sudo cp -r /usr/share/easy-rsa /etc/openvpn

Update the file /etc/openvpn/easy-rsa/vars:

   export EASY_RSA="/etc/openvpn/easy-rsa"

   export KEY_SIZE=2048

Create Certificates

These should be built into the /etc/openvpn/easy-rsa/keys directory

   cd /etc/openvpn/easy-rsa

   sudo su

   source vars

   ln -s openssl-1.0.0.cnf openssl.conf

   ./clean-all

   # build CA cert

   ./build-ca OpenVPN

   # build server key files

   ./build-key-server server

   # build client key files

   ./build-key client1

   ./build-key client2

   # build Diffie-Hellman key exchange

   ./build-dh

   # static Pre-Shared Key PSK

   openvpn --genkey --secret ta.key

Create Server Configuration File

A default version can be found in /usr/share/doc/openvpn/examples/sample-config-files. Should be named /etc/openvpn/openvpn.conf. However, this is all that is required:

   port 1194

   proto udp

   dev tun

   ca /etc/openvpn/easy-rsa/keysca.crt

   cert /etc/openvpn/easy-rsa/keysserver.crt

   key /etc/openvpn/easy-rsa/keysserver.key

   dh /etc/openvpn/easy-rsa/keysdh2048.pem

   server 10.8.0.0 255.255.255.0

   ifconfig-pool-persist ipp.txt

   keepalive 10 120

   cipher AES-128-CBC

   tls-auth /etc/openvpn/easy-rsa/keysta.key 0

   comp-lzo

   persist-key

   persist-tun

   status /var/log/openvpn-status.log

   log /var/log/openvpn

   verb 3

   explicit-exit-notify 1

Create Client Configuration File

   This is all that is required:

   client 

   dev tun 

   proto udp 

   remote 1194 

   resolv-retry infinite

   nobind

   persist-key

   persist-tun

   mute-replay-warnings

   ns-cert-type server

   key-direction 1

   cipher AES-128-CBC

   comp-lzo

   verb 1

   mute 20

   

   -----BEGIN CERTIFICATE-----

   ...

   -----END CERTIFICATE-----

   

   

   -----BEGIN CERTIFICATE-----

   ...

   -----END CERTIFICATE-----

   

   

   -----BEGIN PRIVATE KEY-----

   ...

   -----END PRIVATE KEY-----

   

   

   #

   # 2048 bit OpenVPN static key

   #

   -----BEGIN OpenVPN Static key V1-----

   ...

   -----END OpenVPN Static key V1-----

   

Routing all Client Traffic Through VPN

To route all traffic through the VPN, the following is added to /etc/openvpn/openvpn.conf:

push "redirect-gateway def1 bypass-dhcp"
push "dhcp-option DNS 208.67.222.222"
push "dhcp-option DNS 208.67.220.220"
push "dhcp-option DNS 8.8.8.8"
user nobody
group nogroup

And the following firewall rule is required to ensure that all traffic initiated from clients will be masqueraded as traffic outgoing from wlan0 (change this to the appropriate interface!):

iptables -t nat -A POSTROUTING -s 10.8.0.0/24 -o wlan0-j MASQUERADE

Installing iptables-persistent can make the firewall rules persistent:

sudo apt-get install iptables-persistent

They are configured with:

iptables-save >/etc/iptables/rules.v4

or better:

dpkg-reconfigure iptables-persistent

To list the NAT tables:

iptables -t nat -vL

It is also necessary to enable IP forwarding by un-commenting net.ipv4.ip_forwarpv4.ip_forward=1 in /etc/sysctl.conf and running sudo sysctl -p

VirtualBox access to SD card through Windows Host

The problem is how to set the wireless details for a headless Raspberry Pi, and so the challenge is how to change a file on an SD card formatted as Ext4 for Linux when Windows doesn't recognise it.

As I'm already running a Centos 7 image of Linux in VirtualBox, one solution is to access the whole, raw SD card direct from that VM.

And this post details exactly how to do this, whilst the VirtualBox man pages can be found here.

1. Get the DeviceID for your SD card reader

As administrator, open a command prompt and type:

wmic diskdrive list brief

2. Create an image representing the SD card

As administrator, navigate create a link file to the SD card on the desktop:

cd c:\Program Files\Oracle\VirtualBox
VBoxManage.exe internalcommands createrawvmdk -filename "%USERPROFILE%/Documents/sdcard.vmdk" -rawdisk "\\.\PHYSICALDRIVE1"

3. Connect the VM to the SD card using the link

Open VirtualBox as administrator, and open the Settings for the VM. Go to Storage -> Controller: SATA -> (right click) Add Hard Disk -> Choose Existing Disk and open the file that was created in Documents (note VM must be powered off).
.

4. Access...

Start the VM and mount the card using the GUI. The card should now be accessible in native Ext4 format...

Setting up an SSH Git server on Windows...

I have a set of Raspberry Pis and I need to back up the stuff I do on them, and ideally add some version control as that is always good.
So the idea is to set up a git server on my Windows machine, giving me the ability to both version control the stuff I am doing, and back it up through the pre-existing Windows backup. And the assumption is that anything not in git can be recreated easily enough.
This and the follow up here are the best tutorials I've come across describing this, but full details here:

Install SSH

I'm using the new Microsoft supported OpenSSH.

• unzip the package at C:\Program Files\OpenSSH-Win64 and follow the installation instructions.
• Check the installation by connecting to the Windows machine through SSH.

Note that there OpenSSH isn't yet mature enough for this to work correctly. Worth instead using Bitvise SH Server which is free for limited use.

Install Git

• Download git for Windows and install. Suggest install either git bash, or git bash + cmd option.
• Update PATH to add C:\Program Files\Git\mingw64\libexec\git-core and C:\Program Files\Git\bin
• Create a new file in C:\Program Files\Git\bin named gup.sh. his removes additional single quotes that are added by ssh from Linux to windows:

"C:/Program Files/Git/mingw64/libexec/git-core/git-upload-pack.exe" $*

• Create a second new file named grp.sh:

"C:/Program Files/Git/mingw64/libexec/git-core/git-receive-pack.exe" $*

How to use:

To clone:

git clone -u 'sh gup.sh' user@laptop:C:/Temp/new-project.git

To push:

git push --exec 'sh grp.sh' user@laptop:C:/Temp/new-project.git master
To pull:

git pull --upload-pack 'sh gup.sh' user@laptop:C:/Temp/new-project.git

Alternatively, update ~/.gitconfig using (see here):
git config --global remote.origin.uploadpack 'sh gup.sh'
git config --global remote.origin.receivepack 'sh grp.sh'

To create an empty project:

On remote server:

mkdir new-project.git

cd new-project.git

git init --bare

On local machine:
cd new-project

git init
git add *
git commit -m "Initial commit"
git remote add origin user@laptop:C:/Temp/new-project.git
git push origin master

To set up Public Key Authentication

On remote server (linux):
ssh-keygen –t rsa
or (Windows):
ssh-keygen.exe -t rsa -f id_rsa

(For OpenSSH) Copy the contents of ~/.ssh/rsa_id.pub and add to %systemdrive%\users\user\\.ssh\authorized_keys on host.

Alternatively...

Use Bitvise SSH Server as it is better...

X11 forwarding...

Easiest way is to use Putty and Xming.

Have tried Cygwin/X, but seems overly complex: Xming appears to be the simpler answer.

Just need to make sure X11 forwarding is set on Putty, and everything else should just work...

Windows 10 and MS Money...

...don't seem to work together: Money fails with an error stating it expects IE6.

The initial solution appears to be to update the registry with the following, which seems to work:

[HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\Internet Explorer]
"Version"="9.11.10240.0"

The full thread can be found here.

Getting the new Dell Working...

Lovely computer, but would prefer if it had worked out of the box!!

Flickering screen on batteries is fixed by switching off Display Power Saving Technology on Intel HD Graphics Control Panel (see thread here).

Then the laptop not coming out of sleep is ironically, the Intel Rapid Start Technology. This needs to be switched off...!

Source Code Pro...

Currently enjoying the Source Code Pro font, which can be downloaded from here: the OTF version is the newest font type...

Note to stop xterm opening with cygwinx, type touch ~/.startxwinrc in the bash terminal. See here

Setting up the Slide Scanner

Always manage to struggle with this one, but you need to:

• Connect scanner and power on before powering on PC
• Install Hamrick Vuescan (free update period has ended, so stick with version 8.4.60) including the provided drivers
• Unpack SCSI drivers (aic78xx_aic78u2_vista_x86_v605456.exe)
• Through Device Manager, locate the SCSI card, and install the unpacked drivers
• Register Vuescan, using the details in .\Assorted Stuff\Vuescan Account Details.pdf

And it should all work well, although the SCSI card appears to conflict with the sound card for some reason...

Could not resolve host: mirrors.fedoraproject.org; Name or service not known...

In VirtualBox. Turns out it is easy to fix...

[root@localhost ~]# vi /etc/resolv.conf
nameserver 8.8.8.8
nameserver 8.8.4.4
[root@localhost ~]#

However, this file is auto generated by network-manager, so you need to add the following to the appropriate /etc/sysconfig/network-scripts/ifcfg-* file:

PEERDNS="no"
DNS1="8.8.8.8"
DNS2="8.8.4.4"

And restart the network manager:

[root@localhost ~]# systemctl restart network

Should all work perfectly...

IP Addresses and Computer Names...

I couldn't ping a computer name, just an IP address. And the internet (in its wisdom) posted a fix here.

Update /etc/nsswitch.conf to add "wins" to the line "hosts:"

And you also need to install samba, samba-common and samba-winbind...