Creating a virtual ethernet adapter

Exise · 04-14-2010, 09:01 AM

I am trying to setup a VPN using OpenVPN to allow a secure connection between my smartphone and my LAN. I have been reading an OpenVPN book and some tutorials on how to setup the server side, but I'm stuck at how to create a virtual device.

The OpenVPN book says when installing OpenVPN the installer (or aptitude to be more precise) should ask me if it should create a TAP/TUN device. The thing is, it doesn't ask me anything at all. It just installs, that's it.

Most tutorials simply tell me to create a new device in the network/interfaces file.

Where is the difference? What should I do now? I like having options, that is one reason I like Linux, but this does confuse me.

My second question is about the IP range of the virtual adapter. Should it be in the same range as my LAN, or should I use something entirely different?

catkin · 04-15-2010, 02:51 AM

I'm answering this because nobody else has rather than because I'm knowledgeable on the subject. What I do know comes from configuring bridge/tap/tun for VirtualBox, when it still needed them. Here's the interfaces file. I may be a helpful starting point for you.

Code:

# eth0 is the physical interface.
# Bridging software will configure eth0 when it is added as a port to br0 (below)
# This minimal configuration avoids message "Ignoring unknown interface eth0=eth0"
auto eth0
iface eth0 inet manual
up ifconfig $IFACE 0.0.0.0 up
down ifconfig $IFACE down

# tap0 is a tap into the bridge defined below
# * tap0 is for use by VirtualBox
# * Guest OS will configure, hence "manual"
# * VirtualBox will be run by user c, hence user c
# * "ifconfig" is part of ifupdown package 
# * "tunctl_user" is part of tunctl package
auto tap0 
iface tap0 inet manual 
up ifconfig $IFACE 0.0.0.0 up 
down ifconfig $IFACE down 
tunctl_user c 

# 5apr9 Added tap1, same as tap0, for second VirtualBox VM
auto tap1 
iface tap0 inet manual 
up ifconfig $IFACE 0.0.0.0 up 
down ifconfig $IFACE down 
tunctl_user c 

# br0 is a bridge connecting physical interface eth0 to OS, tap0 and tap1
# * Stanzas for br0 ports must appear before the br0 stanza
# * Static configuration 
# * No need for spanning tree protocol (stp) because no other bridges on network
# 5apr9 Added tap1
iface br0 inet static
address 192.168.0.11 
network 192.168.0.0
netmask 255.255.255.0 
broadcast 192.168.0.255
gateway 192.168.0.253
bridge_ports eth0 tap0 tap1
bridge_maxwait 0 
bridge_stp off