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author | Stefan Kreutz <mail@skreutz.com> | 2020-07-22 14:55:23 +0200 |
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committer | Stefan Kreutz <mail@skreutz.com> | 2020-07-22 14:55:23 +0200 |
commit | e16850ecc3cdf17cf7b5acb70a712cf46cee94b8 (patch) | |
tree | 1a9d7482079d7153aed46e0c7f9b728997c108a0 /_drafts/autoinstall-openbsd-on-qemu.md | |
parent | 3f0545d4bd1837509c20d6c9924b7e5544c8b821 (diff) | |
download | blog-e16850ecc3cdf17cf7b5acb70a712cf46cee94b8.tar |
Post OpenBSD on QEMU
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-rw-r--r-- | _drafts/autoinstall-openbsd-on-qemu.md | 241 |
1 files changed, 0 insertions, 241 deletions
diff --git a/_drafts/autoinstall-openbsd-on-qemu.md b/_drafts/autoinstall-openbsd-on-qemu.md deleted file mode 100644 index 4550fcc..0000000 --- a/_drafts/autoinstall-openbsd-on-qemu.md +++ /dev/null @@ -1,241 +0,0 @@ ---- -title: Auto-install OpenBSD on QEMU -description: How to perform an unattended installation of OpenBSD on the QEMU virtual machine monitor. -published: 2020-07-21 ---- - -<!-- TODO: Update published date in post and script. --> - -I happen to develop a pet project of mine on a Linux desktop, while actually targeting an [OpenBSD](https://www.openbsd.org/) server. -Thus I searched for a scriptable way to install OpenBSD on the [QEMU](https://www.qemu.org/) virtual machine manager, such that I could automate a local integration test against OpenBSD running on Linux. - -As expected, OpenBSD has a remarkably straightforward unattended installation solution. -During a normal, interactive installation, you answer a series of questions like what timezone you are in or which file sets to install. -At the end of the installation, the installer sends a recorded list of those questions along with your answers to the root user's mail box. -You can then adapt this so-called _response file_ to your needs and feed it to the [autoinstall(8)](https://man.openbsd.org/OpenBSD-6.7/autoinstall) command to perform an unattended installation. - -In the remainder of this post, I show how to auto-install OpenBSD/amd64 6.7 on the QEMU PC system emulator 5.0.0. -In the end, I will present a simple yet [complete POSIX shell script](/files/autoinstall-openbsd-on-qemu.sh) to get the job done. -The script is intended to run on Linux, though. -If you already have a running OpenBSD installation, you should consider to use OpenBSD's own hypervisor [vmm(4)](https://man.openbsd.org/OpenBSD-6.7/vmm) instead of QEMU as described in the [OpenBSD FAQ](https://www.openbsd.org/faq/faq16.html) and in this [blog post](https://eradman.com/posts/autoinstall-openbsd.html) by Eric Radman. - -We will perform the following steps: - -1. Install prerequisites -1. Setup a local OpenBSD mirror -1. Configure the installation -1. Setup a network boot environment -1. Install the virtual machine -1. Log in to the virtual machine - -## Install prerequisites - -We will use the following tools: - -* [curl](https://curl.haxx.se/), a data transfer tool (and library) -* [OpenSSH](https://www.openssh.com/portable.html), a remote login tool -* [QEMU](https://www.qemu.org/), a virtual machine monitor -* [rsync](https://rsync.samba.org/), an incremental file transfer tool -* [signify](https://github.com/aperezdc/signify), a cryptographic signature tool -* [socat](http://www.dest-unreach.org/socat/), a successor of the infamous TCP/IP Swiss Army knife, [netcat](https://nc110.sourceforge.io/) - -Chances are that your Linux distribution of choice packages these tools. -For example, the following command installs them on Arch Linux: - - $ sudo pacman -S curl openssh qemu rsync signify socat - -## Setup a local OpenBSD mirror - -To begin with, we setup a partial, local [OpenBSD mirror](https://www.openbsd.org/ftp.html). - -First, we create the [directory layout](https://www.openbsd.org/ftp.html#layout): - - $ mkdir -p mirror/pub/OpenBSD/6.7/amd64 - -Second, we fetch the base public key from the official HTTPS mirror using [curl(1)](https://curl.haxx.se/docs/manpage.html): - - $ curl \ - --output mirror/pub/OpenBSD/6.7/openbsd-67-base.pub \ - https://ftp.openbsd.org/pub/OpenBSD/6.7/openbsd-67-base.pub - -Third, we fetch the kernel, the [PXE](https://en.wikipedia.org/w/index.php?title=Preboot_Execution_Environment&oldid=955913424) bootstrap program, and the file sets from an untrusted [rsync mirror](https://www.openbsd.org/ftp.html#rsync) using [rsync(1)](https://download.samba.org/pub/rsync/rsync.1): - - $ rsync --archive --files-from=- --verbose \ - rsync://ftp.halifax.rwth-aachen.de/openbsd/6.7/amd64/ \ - mirror/pub/OpenBSD/6.7/amd64 \ - << EOF - SHA256.sig - base67.tgz - bsd - bsd.mp - bsd.rd - comp67.tgz - game67.tgz - man67.tgz - pxeboot - xbase67.tgz - xfont67.tgz - xserv67.tgz - xshare67.tgz - EOF - -Fourth, we verify the fetched files using [signify(1)](https://man.openbsd.org/OpenBSD-6.7/signify) and the previously fetched base public key:[^sha256] - - $ ( cd mirror/pub/OpenBSD/6.7/amd64 && signify -C \ - -p ../openbsd-67-base.pub \ - -x SHA256.sig \ - -- bsd bsd.* pxeboot *67.tgz ) - -Finally, we serve the local mirror at <http://127.0.0.1:8080/>. -Feel free to use your web server of choice. -Chances are, that your Linux distribution comes with Python's [http.server module](https://docs.python.org/3/library/http.server.html): - - $ python3 \ - -m http.server \ - --directory mirror \ - --bind 127.0.0.1 8080 - -## Configure the installation - -First, we create a response file for [autoinstall(8)](https://man.openbsd.org/OpenBSD-6.7/autoinstall) at `mirror/install.conf`:[^response-file] - - Change the default console to com0 = yes - Which speed should com0 use = 115200 - System hostname = openbsd - Password for root = ************* - Allow root ssh login = no - Setup a user = puffy - Password for user = ************* - Public ssh key for user = ssh-rsa AAAAB3N... alex@example - What timezone are you in = UTC - Location of sets = http - HTTP Server = 10.0.2.1 - Unable to connect using https. Use http instead = yes - URL to autopartitioning template for disklabel = http://10.0.2.1/disklabel - Set name(s) = site67.tgz - Checksum test for site67.tgz failed. Continue anyway = yes - Unverified sets: site67.tgz. Continue without verification = yes - -Take care to insert your own public SSH key here, for example, the contents of `~/.ssh/id_rsa.pub`. - -Note that we effectively disable password-based authentication here by assigning the conventional 13 asterisks as encrypted passwords for both users, `root` and `puffy`, see [passwd(5)](https://man.openbsd.org/OpenBSD-6.7/passwd.5). -Instead, we enable the user `puffy` to login using the given SSH key. -Besides, we will later permit the user `puffy` to run any command as root without entering his password using [doas(1)](https://man.openbsd.org/OpenBSD-6.7/doas). - -Note also that we will later instruct QEMU to redirect port 80 on the virtual network address 10.0.2.1 to port 8080 on the local host. - -Next, we create a [disklabel(8)](https://man.openbsd.org/OpenBSD-6.7/disklabel) template at `mirror/disklabel`: - - / 2G - swap 8G - /tmp 1G - /var 1G - /usr 2G - /usr/X11R6 500M - /usr/local 4G - /usr/src 1M - /usr/obj 1M - /home 4G - -Finally, we create an optional site-specific file set. -This way, we can run some commands at the end of the installation. -Here, we reset the OpenBSD mirror server used by [pkg_add(1)](https://man.openbsd.org/OpenBSD-6.7/pkg_add) and other commands.[^restrict-network] -Moreover, we permit the wheel user group --- and thus the user `puffy` --- to run any command as root without entering their password using [doas(1)](https://man.openbsd.org/OpenBSD-6.7/doas). - -Create the file `site/install.site`: - -``` -#! /bin/ksh -set -o errexit -echo "https://cdn.openbsd.org/pub/OpenBSD" > /etc/installurl -echo "permit nopass keepenv :wheel" >> /etc/doas.conf -``` - -Then, make the file executable, package the file set, and add it to the local OpenBSD mirror: - - $ chmod +x site/install.site - $ ( cd site && tar -czf ../mirror/pub/OpenBSD/6.7/amd64/site67.tgz . ) - $ ( cd mirror/pub/OpenBSD/6.7/amd64 && ls -l > index.txt ) - -## Setup a network boot environment - -We create a dedicated directory to serve the OpenBSD kernel and PXE bootstrap program over [TFTP](https://en.wikipedia.org/w/index.php?title=Trivial_File_Transfer_Protocol&oldid=959587822): - - $ mkdir tftp - $ ln -s ../mirror/pub/OpenBSD/6.7/amd64/pxeboot tftp/auto_install - $ ln -s ../mirror/pub/OpenBSD/6.7/amd64/bsd.rd tftp/bsd.rd - -Furthermore, we create a [boot(8)](https://man.openbsd.org/OpenBSD-6.7/man8/amd64/boot.8) configuration file at `tftp/etc/boot.conf`: - - stty com0 115200 - set tty com0 - boot tftp:/bsd.rd - -## Install the virtual machine - -First, we create a copy-on-write disk image using [qemu-img(1)](https://www.qemu.org/docs/master/tools/qemu-img.html): - - $ qemu-img create -f qcow2 disk.qcow2 24G - -Then, we start a virtual machine --- and thus the unattended installation of OpenBSD --- off this disk using [qemu-system-x86_64(1)](https://www.qemu.org/docs/master/system/qemu-manpage.html) and [socat(1)](http://www.dest-unreach.org/socat/doc/socat.html): - - $ qemu-system-x86_64 \ - -enable-kvm \ - -smp "cpus=4" \ - -m 4G \ - -drive "file=disk.qcow2,media=disk,if=virtio" \ - -device e1000,netdev=n1 \ - -netdev "user,id=n1,hostname=openbsd-vm,tftp-server-name=10.0.2.1,tftp=tftp,bootfile=auto_install,hostfwd=tcp::2222-:22,guestfwd=tcp:10.0.2.1:80-cmd:socat STDIO TCP4:127.0.0.1:8080" \ - -nographic - -Let's break this last command down. -The `-enable-kvm` option enables the Linux [Kernel-based Virtual Machine (KVM)](https://www.linux-kvm.org/) support. -The `-smp` option instructs QEMU to simulate a [symmetric multiprocessing (SMP)](https://en.wikipedia.org/w/index.php?title=Symmetric_multiprocessing&oldid=951686602) system. -The `-m` option sets the amount of virtual memory. -The `-drive` option attaches the previously created copy-on-write disk image as a [Virtio](https://wiki.libvirt.org/page/Virtio) disk drive. -The `-device` option attaches a standard network adapter. -The `-netdev` option configures a virtual network `10.0.2.0/24` where `10.0.2.2` and `10.0.2.15` point to the QEMU host and guest respectively. -Moreover, we instruct QEMU to (a) run an embedded TFTP server, (b) redirect port 2222 on the host to port 22 on the guest, and (c) redirect port 80 on the virtual host address `10.0.2.1` to port 8080 on the host. -The former port redirection enables us to log in to the guest using [ssh(1)](https://man.openbsd.org/OpenBSD-6.7/ssh), and the latter port redirection frees us from binding to the privileged port 80 on the host.[^socat] -Finally, the `-nographic` option turns QEMU into a command-line application that redirects the emulated serial port to the console. -Press `C-a x` to stop the virtual machine, or `C-a h` to show other options. - -## Log in to the virtual machine - -Once the virtual machine has booted, you can login as the user `puffy` using [ssh(1)](https://man.openbsd.org/OpenBSD-6.7/ssh): - - ssh \ - -o "StrictHostKeyChecking no" \ - -o "UserKnownHostsFile /dev/null" \ - -o "Port 2222" \ - puffy@127.0.0.1 - -Here, we use the `StrictHostKeyChecking` and `UserKnownHostsFile` options to keep the presumably temporary virtual machine's host key out of our known hosts file. - -## Conclusion - -We auto-installed OpenBSD/amd64 6.7 on the QEMU PC system emulator 5.0.0 by means of several command-line tools. -First, we setup a partial, local OpenBSD mirror using [rsync(1)](https://download.samba.org/pub/rsync/rsync.1) and [signify(1)](https://man.openbsd.org/OpenBSD-6.7/signify). -Second, we prepared a response file for [autoinstall(8)](https://man.openbsd.org/OpenBSD-6.7/autoinstall), a [disklabel(8)](https://man.openbsd.org/OpenBSD-6.7/disklabel) template, and a site-specific file set. -Third, we setup a standard network boot environment. -Fourth, we actually installed OpenBSD on a QEMU guest machine. -Finally, we logged in to the virtual machine using [ssh(1)](https://man.openbsd.org/OpenBSD-6.7/ssh). - -Of course, you can automate the whole process. -For example, I use a simple, yet [complete POSIX shell script](/files/autoinstall-openbsd-on-qemu.sh) to auto-install OpenBSD on QEMU. -In fact, I have written another script to install and test the said pet project of mine as well. -But this is out of scope here. - -[^sha256]: - You can also verify the [SHA256 checksums](https://ftp.openbsd.org/pub/OpenBSD/6.7/amd64/SHA256) of the fetched files if you cannot use [signify(1)](https://man.openbsd.org/OpenBSD-6.7/signify). - -[^response-file]: - You can serve per-host response files for [autoinstall(8)](https://www.tumfatig.net/20190426/openbsd-automatic-upgrade/) by prefixing the MAC address or the hostname. - Besides, you can add the response file to the RAM disk kernel `bsd.rd` using [rdsetroot(8)](https://man.openbsd.org/OpenBSD-6.7/rdsetroot). - -[^restrict-network]: - You can create a fully isolated virtual machine by (a) including patches, packages, and ports in your local OpenBSD mirror, and (b) restricting the virtual network created by QEMU. - -[^socat]: - I failed to forward port 80 on the virtual host address to port 8080 on the local host using [qemu-system-x86_64(1)](https://www.qemu.org/docs/master/system/qemu-manpage.html)'s `guestfwd` alone. - Instead, I resorted to the invaluable [socat(1)](http://www.dest-unreach.org/socat/doc/socat.html). |