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Create Jail, Networking and NAT

Create Classic Jails

Step 1: Enable IP Forwarding

First, you need to enable IP forwarding on your FreeBSD host. This allows the host to forward packets between the jail and the outside network.

Step 1:

Edit the /etc/sysctl.conf file and add the following line:

net.inet.ip.forwarding=1

Apply the changes:

sysctl net.inet.ip.forwarding=1

Step 2: Configure the Host Network Interface

You need to configure the host's network interface to allow NAT.

Identify your network interface (e.g., em0, re0, etc.) using:

ifconfig

Set up NAT using pf (Packet Filter). First, ensure that pf is enabled. Edit /etc/rc.conf and add:

pf_enable="YES"

Create or edit the /etc/pf.conf file to include NAT rules. Here’s a basic example:

ext_if="eth0"  # Replace with your external interface
jails_net="10.10.10.0/24"  # Replace with your jail network

# Set the default policy
set block-policy return
set loginterface $ext_if

# Jail
nat on $ext_if from $jails_net to any -> ($ext_if)
pass in on $ext_if proto tcp from any to ($ext_if) port { 22, 80, 443 }

# Block all incoming traffic by default
block in all

# Allow incoming traffic on specific ports
pass in on $ext_if proto tcp from any to any port { 22, 80, 443 }

# Allow all outgoing traffic
pass out all

Load the pf rules:

sysrc pf_enable="YES"
kldload pf
pfctl -f /etc/pf.conf
pfctl -e

Create Classic Jails

Step 1: Enable the Jail Feature

Make sure the jail feature is enabled in your FreeBSD system. You can check this by looking for the jail keyword in your /etc/rc.conf file. If it's not there, you can add it.

echo 'jail_enable="YES"' >> /etc/rc.conf

Step 2: Create a Directory for the Jail

Create a directory where the jail's filesystem will reside. This is typically done in /usr/jails.

mkdir -p /usr/jails/website

Step 3: Install the Base System

You need to populate the jail directory with a FreeBSD base system. You can use the make command to extract the base system into the jail directory.

mkdir -p /usr/jails/website
mkdir /usr/jail/media
fetch https://download.freebsd.org/ftp/releases/amd64/amd64/14.2-RELEASE/base.txz -o /usr/jails/media/14.2-RELEASE-base.txz
tar -xf /usr/jails/media/14.2-RELEASE-base.txz -C /usr/jails/website --unlink

Setp 4: Copy important Files & Update

cp /etc/resolv.conf /usr/jails/website/etc/resolv.conf
cp /etc/localtime /usr/jails/website/etc/localtime
freebsd-update -b /usr/jails/website fetch install

Step 5: Create Network interface for Jail

sysrc cloned_interfaces+="lo1"

Step 6: Configure the Jail in /etc/jail.conf:

website {
    path = "/usr/jails/website";
    sysvshm = "new";
    host.hostname = "website.local";
    ip4.addr = "lo1|10.10.10.100/24";  # Assign an IP from your jail network
    allow.raw_sockets;
    allow.socket_af;
    allow.mount;
    mount.devfs;
    devfs_ruleset = 111;
    exec.clean;
    exec.start = "/bin/sh /etc/rc";
    exec.stop = "/bin/sh /etc/rc.shutdown";
}

Step 7: Reboot

Reboot Host

reboot

Step 8: Start the Jail

jail -c website

Now you should have a jail with networking

Destroy Jail

service jail stop website
chflags -R 0 /usr/jails/website/
rm -rf /usr/jails/website/
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