Network Requirements

Here’s the scenario. You’ve installed Bastille at home or in the cloud and want to get started putting applications in secure little containers, but how do you get these containers on the network? Bastille tries to be flexible about how to network containerized applications. Four methods are described here.

  1. Home or Small Office
  2. Cloud with IPV4 and multiple IPV6
  3. Could with single IPV4 (internatl bridge)
  4. Cloud with a single IPV4 (external bridge)

Please choose the option which is most appropriate for your environment.

First a few notes. Bastille tries to verify that the interface name you provide is a valid interface. In FreeBSD network interfaces have different names, but look something like em0, bge0, re0, vtnet0 etc. Running the ifconfig commend will tell you the name of your existing interfaces. Bastille also checks for a valid syntax IP4 or IP6 address. When you are testing calling out from your containers, please note that the ping command is disabled within the containers, because raw socket access are a security hole. Instead I install and test with wget instead.

Shared Interface on Home or Small Office Network

If you have just one computer, or a home or small office network, where you are separated from the rest of the internet by a router. So you are free to use private IP addresses <>.

In this environment, to use Bastille, just create the container, give it a unique private ip address, and attach its ip address to your primary interface.

bastille create alcatraz 13.1-RELEASE em0

You may have to change em0

When the alcatraz container is started it will add as an IP alias to the em0 interface. It will then simply be another member of the hosts network. Other networked systems (firewall permitting) should be able to reach services at that address.

This method is the simplest. All you need to know is the name of your network interface and a free IP on your local network.

Shared Interface on IPV6 network (

Some ISP’s, such as <>, give you a single ipv4 address, and a large block of ipv6 addresses. You can then assign a unique ipv6 address to each Bastille Container.

On a virtual machine such as the virtual interface may be vtnet0. So we issue the command:

bastille create alcatraz 13.1-RELEASE  2001:19f0:6c01:114c::100 vtnet0

We could also write the ipv6 address as 2001:19f0:6c01:114c:0:100

The tricky part are the ipv6 addresses. IPV6 is a string of 8 4 digit hexadecimal characters. At vultr they said:

Your server was assigned the following six section subnet:

2001:19f0:6c01:114c:: / 64

The vultr ipv6 subnet calculator <> is helpful in making sense of that ipv6 address.

We could have also written that IPV6 address as 2001:19f0:6c01:114c:0:0

Where the /64 basicaly means that the first 64 bits of the address (4x4 character hexadecimal) values define the network, and the remaining characters, we can assign as we want to the Bastille Container. In the actual bastille create command given above, it was defined to be 100. But we also have to tell the host operating system that we are now using this address. This is done on freebsd with the following command

ifconfig_vtnet0_alias0="inet6 2001:19f0:6c01:114c::100  prefixlen 64"

At that point your container can talk to the world, and the world can ping your container. Of course when you reboot the machine, that command will be forgotten To make it permanent, you have to add it to the file /etc/rc.conf

Just remember you cannot ping out from the container. Instead I installed and used wget to test the connectivity.

Use the bastille pkg command to install wget.

bastille pkg alcatraz install wget

Virtual Network (VNET)

(Added in 0.6.x) VNET is supported on FreeBSD 12+ only.

Virtual Network (VNET) creates a private network interface for a container. This includes a unique hardware address. This is required for VPN, DHCP, and similar containers.

To create a VNET based container use the -V option, an IP/netmask and external interface.

bastille create -V azkaban 13.1-RELEASE em0

Bastille will automagically create the bridge interface and connect / disconnect containers as they are started and stopped. A new interface will be created on the host matching the pattern interface0bridge. In the example here, em0bridge.

The em0 interface will be attached to the bridge along with the unique container interfaces as they are started and stopped. These interface names match the pattern eXb_bastilleX. Internally to the containers these interfaces are presented as vnet0.

VNET also requires a custom devfs ruleset. Create the file as needed on the host system:

## /etc/devfs.rules (NOT .conf)

add path 'bpf*' unhide

Lastly, you may want to consider these three sysctl values:

Regarding Routes

Bastille will attempt to auto-detect the default route from the host system and assign it to the VNET container. This auto-detection may not always be accurate for your needs for the particular container. In this case you’ll need to add a default route manually or define the preferred default route in the bastille.conf.

bastille sysrc TARGET
bastille service TARGET routing restart

To define a default route / gateway for all VNET containers define the value in bastille.conf:

This config change will apply the defined gateway to any new containers. Existing containers will need to be manually updated.

Virtual Network (VNET) on External Bridge

To create a VNET based container and attach it to an external, already existing bridge, use the -B option, an IP/netmask and external bridge.

bastille create -B azkaban 13.1-RELEASE bridge0

Bastille will automagically create the interface, attach it to the specified bridge and connect / disconnect containers as they are started and stopped. The bridge needs to be created/enabled before creating and starting the jail.

Public Network

In this section we describe how to network containers in a public network such as a cloud hosting provider who only provides you with a single ip address. (AWS, digital ocean, etc) (The exception is, which does provide you with lots of IPV6 addresses and does a great job supporting FreeBSD!)

So if you only have a single IP address and if you want to create multiple containers and assign them all unique IP addresses, you’ll need to create a new network.

loopback (bastille0)

What we recommend is creating a cloned loopback interface (bastille0) and assigning all the containers private (rfc1918) addresses on that interface. The setup I develop on and use Bastille day-to-day uses the address range. I have the ability to use whatever address I want within that range because I’ve created my own private network. The host system then acts as the firewall, permitting and denying traffic as needed.

I find this setup the most flexible across all types of networks. It can be used in public and private networks just the same and it allows me to keep containers off the network until I allow access.

Having said all that here are instructions I used to configure the network with a private loopback interface and system firewall. The system firewall NATs traffic out of containers and can selectively redirect traffic into containers based on connection ports (ie; 80, 443, etc.)

First, create the loopback interface:

ishmael ~ # sysrc cloned_interfaces+=lo1
ishmael ~ # sysrc ifconfig_lo1_name="bastille0"
ishmael ~ # service netif cloneup

Second, enable the firewall:

ishmael ~ # sysrc pf_enable="YES"

Create the firewall rules:



set block-policy return
scrub in on $ext_if all fragment reassemble
set skip on lo

table <jails> persist
nat on $ext_if from <jails> to any -> ($ext_if:0)
rdr-anchor "rdr/*"

block in all
pass out quick keep state
antispoof for $ext_if inet
pass in inet proto tcp from any to any port ssh flags S/SA modulate state
  • Make sure to change the ext_if variable to match your host system interface.
  • Make sure to include the last line (port ssh) or you’ll end up locked out.

Note: if you have an existing firewall, the key lines for in/out traffic to containers are:

nat on $ext_if from <jails> to any -> ($ext_if)

The nat routes traffic from the loopback interface to the external interface for outbound access.

rdr-anchor "rdr/*"

The rdr-anchor “rdr/*” enables dynamic rdr rules to be setup using the bastille rdr command at runtime - eg.

bastille rdr <jail> tcp 2001 22 # Redirects tcp port 2001 on host to 22 on jail
bastille rdr <jail> udp 2053 53 # Same for udp
bastille rdr <jail> list        # List dynamic rdr rules
bastille rdr <jail> clear       # Clear dynamic rdr rules

Note that if you are redirecting ports where the host is also listening (eg. ssh) you should make sure that the host service is not listening on the cloned interface - eg. for ssh set sshd_flags in rc.conf

sshd_flags=”-o ListenAddress=<hostname>”

Finally, start up the firewall:

ishmael ~ # service pf restart

At this point you’ll likely be disconnected from the host. Reconnect the ssh session and continue.

This step only needs to be done once in order to prepare the host.