Running servers in crouton

Edit: Very interesting and useful post. I was able to use the iptables command to turn my Chromebook into a media server. However, the below is very misleading. It is unnecessary to open a port in your chroot, as it is already wide open, unless you installed a firewall package after setting up your chroot. Most Linux installs, like Debian or Ubuntu, do not install a firewall, and you can immediately setup a server which will be accessible from other devices in your network, without using iptables.

Your Chromebook, however, is very secure. If you're running a server in your chroot, no other devices on the network will be able to connect to it, because it is shielded by ChromeOS. The trick is, you have to open a port on your Chromebook itself, then the server will be accessible!

So, from the shell, enter the command, sudo /sbin/iptables -P INPUT ACCEPT, which will accept all incoming connections. Or use the more restrictive, sudo /sbin/iptables -I INPUT -p tcp --dport 22 -j ACCEPT , which, in this example, only allows port 22, which is ssh. Change the 22 to whatever port your server uses. For the Emby Media Server, it is 8096.

One more point: each line in your rc.local needs to end in &, otherwise, Crouton will throw an error.

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If you plan to run a server within crouton, you'll need the following:

1. Open a terminal session in your chroot.
2. Install the iptables package, sudo apt-get install iptables
3. Add a line to /etc/rc.local to launch the service you want. Examples for different services are given below.
4. Add a line to /etc/rc.local to open the firewall, for example:
   1. /sbin/iptables -P INPUT ACCEPT to accept all inbound traffic.
   2. /sbin/ip6tables -P INPUT ACCEPT to accept all inbound IPv6 traffic. Or,
   3. /sbin/iptables -I INPUT -p tcp --dport 22 -j ACCEPT to accept a specific port, e.g. 22 for the SSH example.

This will start the server when the chroot is started, not when ChromeOS is booting. To auto-start the chroot on ChromeOS boot, see these instructions.

OpenSSH Server

Add the following to /etc/rc.local to enable ssh into your chroot. Tested in Ubuntu 13.10. Previously /etc/init.d/ssh start was all that was needed. Works well with Secure Shell Chrome app.

On Jessie and Sid only the iptables rule is needed. sudo system ssh start will work to start the server.

mkdir -p -m0755 /var/run/sshd
/usr/sbin/sshd

[update] In Debian 11 Bullseye install the usual ssh stuff via your package manager and open port 22 like this:

iptables-legacy -A INPUT -p tcp --dport 22 -m conntrack --ctstate NEW,ESTABLISHED -j ACCEPT

Don't use iptables-nft because it's broken in Debian 11 or it has troubles running in a chroot. And nowadays we don't know if the command iptables is a symlink to iptables-nft or iptables-lecacy so don't use that either.

Then start the ssh server daemon like this:

sudo service ssh start

Check status with sudo service ssh .

Commands that use systemctl (from systemd) instead of service do not work in a chroot and therefore do not work in Crouton.

avahi and mDNS

1. Install the avahi-daemon, avahi-utils and libnss-mdns packages, sudo apt-get install avahi-daemon avahi-utils libnss-mdns
2. In the /etc/avahi/avahi-daemon.conf file, uncomment the #host-name=foo record and set the host-name you desire, for example hostname=mychromebook.
3. Add the following to /etc/rc.local to enable avahi in your chroot. Tested in Ubuntu 12.04. Do not run avahi-daemon as a daemon (-D option). Doing so will cause it to miss the configuration parameters in /etc/avahi and fail.

/usr/sbin/avahi-daemon --syslog &

Optionally, if you are running an OpenSSH or apache server, add corresponding service files to the /etc/avahi/services directory in order to publicize the service on the local network. An example for OpenSSH:

cat /etc/avahi/services/ssh.service
<service-group>
  <name replace-wildcards="yes">%h</name>
  <service>
    <type>_ssh._tcp</type>
    <port>22</port>
  </service>
</service-group>

A quick test of the service is to ping a known local resource: ping myhomelanserver.local. The the local name should resolve to the server IP address.

LAMP

You'll need to start Apache and MySQL on your rc.local

1. nano /etc/rc.local
2. Paste this using shift+ctrl+v, save with ctrl+x

/etc/init.d/apache2 start

export HOME=/etc/mysql
umask 007
[ -d /var/run/mysqld ] || install -m 755 -o mysql -g root -d /var/run/mysqld
/usr/sbin/mysqld &

3. save with ctrl+x