==== Linux containers ====
Linux containers (LXC) is the Linux implementation of FreeBSD Jails.
Within a Linux container we can run a self-contained installation of Linux
which will utilise the system's kernel.
This is more lightweight method of virtualisation than than offered
by [[:tools:xen|Xen]], for example.
=== Install ===
apt-get install lxc lxc-templates bridge-utils cgroupfs-mount conntrack iptables debootstrap
/etc/init.d/cgroupfs-mount start
===Setup===
Disable lxc services, we will do this stuff manually.
==init.d==
/etc/init.d/lxc-net stop
update-rc.d lxc-net disable
/etc/init.d/lxc stop
update-rc.d lxc disable
killall dnsmasq
==systemd==
systemctl disable lxc-monitord.service
systemctl mask lxc-monitord.service
systemctl disable lxc-net.service
systemctl disable lxc.service
==defaults==
sed -i 's/LXC_AUTO="true"/LXC_AUTO="false"/g' /etc/default/lxc
sed -i 's/USE_LXC_BRIDGE="true"/USE_LXC_BRIDGE="false"/g' /etc/default/lxc-net
=== Networking ===
==Bridge==
Virtual interfaces are bridged on to the primary network interface.
auto eth0
iface eth0 inet manual
auto lxcbr0
iface lxcbr0 inet static
bridge_ports eth0
address 10.10.44.10
netmask 255.255.255.0
gateway 10.10.44.1
==Subnet==
Virtual interfaces are contained on the their own private subnet.
auto lxcbr0
iface lxcbr0 inet static
pre-up brctl addbr lxcbr0
address 10.10.10.1
netmask 255.255.255.0
post-down brctl delbr lxcbr0
==iptables==
Example NAT tables for containers on private subnet.
#! /bin/sh
PATH=/sbin:/usr/sbin:/bin:/usr/bin
iptables -t filter -F
iptables -t filter -X
iptables -t raw -F
iptables -t nat -F
conntrack -F
# raw:PREROUTING
iptables -t raw -A PREROUTING -i lo -j NOTRACK
# raw:OUTPUT
iptables -t raw -A OUTPUT -o lo -j NOTRACK
# filter:INPUT
iptables -t filter -P INPUT ACCEPT
# filter:FORWARD
iptables -t filter -P FORWARD ACCEPT
# filter:OUTPUT
iptables -t filter -P OUTPUT ACCEPT
# nat:POSTROUTING
iptables -t nat -A POSTROUTING -o eth0 -s 10.10.10.0/24 -d 0/0 -j MASQUERADE
sysctl -w net.ipv4.ip_forward=1
sysctl -w net.ipv4.conf.all.proxy_arp=1
sysctl -w net.netfilter.nf_conntrack_max=524288
sysctl -w net.netfilter.nf_conntrack_tcp_timeout_established=7440
echo 65536 > /sys/module/nf_conntrack/parameters/hashsize
echo "1024 65535" > /proc/sys/net/ipv4/ip_local_port_range
exit 0
=== Initialise ===
==Wheezy on IBM PC platform==
lxc-create -n HOSTNAME -t debian -- -r wheezy -a amd64
==Stretch on Raspberry Pi==
lxc-create -n cracker -t debian -- -r stretch -a armhf
==Buster/Bullseye on Raspberry Pi==
Install keys
mkdir -p /var/cache/lxc/debian
wget "https://ftp-master.debian.org/keys/release-10.asc"
gpg --no-default-keyring --keyring /var/cache/lxc/debian/archive-key.gpg --import release-10.asc
wget "https://ftp-master.debian.org/keys/release-11.asc"
gpg --no-default-keyring --keyring /var/cache/lxc/debian/archive-key.gpg --import release-11.asc
Install buster
lxc-create -n cracker -t debian -- -r buster -a armhf
Install bullseye
lxc-create -n terminator -t debian -- -r bullseye -a armhf
Install bookworm (32-bit)
lxc-create -n cracker -t debian -- -r bookworm -a armhf
=== Configure ===
==/var/lib/lxc/HOSTNAME/config==
# Template used to create this container: /usr/share/lxc/templates/lxc-debian
# Parameters passed to the template: -r stretch
# Template script checksum (SHA-1): 5a35ad98c578f5487dc5712a1c7d38af399be813
# For additional config options, please look at lxc.container.conf(5)
# Uncomment the following line to support nesting containers:
#lxc.include = /usr/share/lxc/config/nesting.conf
# (Be aware this has security implications)
#lxc.net.0.type = veth
#lxc.net.0.hwaddr = 00:XX:XX:XX:XX:XX
#lxc.net.0.link = lxcbr0
#lxc.net.0.flags = up
lxc.apparmor.profile = generated
lxc.apparmor.allow_nesting = 1
lxc.rootfs.path = dir:/var/lib/lxc/cheese/rootfs
# Common configuration
lxc.include = /usr/share/lxc/config/debian.common.conf
# Container specific configuration
lxc.tty.max = 4
lxc.uts.name = cheese
lxc.arch = armhf
lxc.pty.max = 1024
# Local network configuration
lxc.net.0.type = veth
lxc.net.0.flags = up
lxc.net.0.link = lxcbr0
lxc.net.0.name = lxcnet0
lxc.net.0.hwaddr = XX:XX:XX:XX:XX:XX
lxc.net.0.veth.pair = veth0
lxc.net.0.ipv4.address = ?/24
lxc.net.0.ipv4.gateway = ?
#lxc.net.0.ipv6.address = ?
#lxc.net.0.ipv6.gateway = ?
# You may need the following for initial boot
#
# You can replace systemd by changing the lxc.init.cmd before rebooting
#
lxc.cgroup.devices.allow =
lxc.cgroup.devices.deny =
lxc.init.cmd = /lib/systemd/systemd systemd.unified_cgroup_hierarchy=1
#lxc.init.cmd = /sbin/init
=== Run ===
Run in background (now the default)
lxc-start -d -n HOSTNAME
Run in foreground (was the default)
lxc-start -F -n HOSTNAME
=== Attach ===
Attach to container and change root password.
lxc-attach -n HOSTNAME
passwd root
=== Stop ===
lxc-stop -n HOSTNAME
=== Unprivileged containers ===
Root can run containers with lower privileges. First we set aside
some user ids to map to the container then configure it.
This has been tested to work Ubuntu vivid and nothing else since.
When assigning a range of ids to the root user. Choose what is available, here i
chose 200000 because this was free.
usermod --add-subuids 200000-265535 root
usermod --add-subgids 200000-265535 root
The host configuration now needs to map the ids in its config.
lxc.id_map = u 0 200000 65536
lxc.id_map = g 0 200000 65536
The container root will be system uid 200000, and nobody in the container will be 265534, for example..
Before starting, the lcx directory needs the execute permission.
chmod +x /var/lib/lxc
Now we can start and stop the container, attach to it, etc.
===Runit===
Start container and login as root
lxc-start -F -n container
Install runit. It will ask you to enter a phrase and after installation reboot.
apt install runit-init
reboot
Login to tidy up.
lxc-attach -n container
cd /etc/service
rm getty-tty*