Posted on Mar 01, 2014 By copyninja under bsd

First step will be getting a NetBSD ISO image for installation purpose. It can be downloaded from here.

Next step will be creating a disk image for installing NetBSD. This is done using qemu-img tool like below

$ qemu-img create -f raw netbsd-disk.img 10G

Image format used is raw and size is specified as last arugment. Tune the size as per your need.

To start the installation run the following command

$ qemu-system-x86_64 -m 256M -hda netbsd-disk.img -cdrom \
             NetBSD-6.1.3-amd64.iso -display curses -boot d \
             -net nic -net user

So this is using user mode networking so you won't be able to have internet access during installation. I couldn't figure out on how to get network working during installation so I configured network after installation.

Once you run above command you will be given with 4 options as follows.

  1. install netbsd
  2. install netbsd with ACPI disabled
  3. install netbsd with ACPI and SMP disabled
  4. drop to boot shell

Even though I first installed using the option 1 I couldn't get it boot after installation so had to reinstall with option 2 and it works fine. I'm not gonna explain each step of installation here because the installer is really simple and straight forward! I guess the NetBSD installer is the first simplest installer I have encountered from the day I started with Linux. Its simple but powerful and gets job done very easily, and I didn't read manual for installation before using it.

Enabling Networking

This section involves mixture of configuration in Debian host and inside NetBSD to get the network working. The wiki page of Debian on Qemu. helped me here.

To share the network with Qemu there are 2 possiblities

  1. Bridged networking between host and guest using bridge-utils
  2. Using VDE (Virtual Distributed Ethernet)

The option 1 which is explained in wiki linked above didn't work for me as I use CDC Ether based datacard for connecting to Internet which gets detected as eth1 on my machine. When bridging happens between tap0 and eth1 I end up loosing Internet on my host machine. So I selected to use VDE instead.

First install packages vde2 and uml-utilities once done edit the /etc/network/interfaces file and add following lines:

auto vdetap
iface vdetap inet static
   vde2-switch -t vdetap

We can use dnsmasq as a DHCP server for the vdetap interface, but I'm not gonna explain the configuration of dnsmasq here. Run the below command to get vdetap up

modprobe tun
ifup vdetap
/etc/init.d/dnsmasq restart
newgrp vde2-net # run as user starting Qemu VM's

I couldn't get successful output for newgrp command, I was getting some crypt: Invalid argument output. But I could still get network working on NetBSD so I considered to ignore that for now.

Now start the NetBSD qemu instance running using following command

$ qemu-system-x86_64 -m 256M -hda \
             /mnt/kailash/BSDWorld/netbsd-disk.img \
             -net nic -net vde,sock=/var/run/vde2/vdetap.ctl -display curses

Once the system is up login using root user, NetBSD will warn you for this and suggest to create another user but for now ignore it. To find the network interface in NetBSD just run the usual ifconfig command. In my case interface is named wm0.

First step will be configuring the IP address for your interface and setting up the gateway route. Run the below command for this purpose

# ifconfig wm0 netmask
# route add default

Note that I added gateway as IP address of vdetap on my host machine. Now try pinging the host and even you can try ssh to host system.

But note that this is not persistent over the reboots and for some reason I didn't yet figure out how to make NetBSD get address over DHCP from my host machine. I will update once I figure it out. Now to make the connection address persistent over reboots you need to create a file by name /etc/ifconfg.<interface>. Replace interface with a proper interface on your running NetBSD. In my case this file is /etc/ifconfig.wm0 and has following content.: netmask 0xffffff00 media autoselect

Set the DNS server as host by adding file /etc/resolv.conf with following content.:


After this you need to do NAT/masquerading using iptables. Just copy following script to a file and execute it as root


# Restart the dnsmasq
/etc/init.d/dnsmasq restart

# Set nat rules in iptables
iptables --flush
iptables --table nat --flush
iptables --delete-chain
iptables --table nat --delete-chain

# Replace accordingly usb0 with ppp0 for 3G
iptables --table nat --append POSTROUTING --out-interface eth1 -j MASQUERADE
iptables --append FORWARD --in-interface vdetap -j ACCEPT

# Enable IP forwarding in Kernel
sysctl -w net.ipv4.ip_forward=1

With the above setup you will be able to get DNS resolution even after you reboot the Qemu instance but Internet connection will not work untill you run the route command I mentioned above. I still didn't figure out how to persist route but I will update it here once I figure it out.

Note that you won't be able to SSH as root to NetBSD (may be its configured to not allow by default), so you would need to create a normal user before trying to SSH from host to guest. Also make sure you add the user to wheel group to allow him execute su command.

So now I've NetBSD running on my laptop with mere 256M ram and its amazingly fast even at such low RAM. I've created a new user and can SSH into it from host machine and use it just like I use a server!. I will put up the notes of my BSD adventure here periodically.

The feeling of using a BSD is amazing :-)

Update: I forgot to add masquerading step, I've added it now.