DangerZone Network

Overview

This article explains the layout of the networks in the DangerZone from the perspective of the gateway.

Wifi Public switch NICs on box vmserver gateway

Networks

There are four different networks that the gateway has to deal with.

Internet

The adapter named eth-pub has a direct connection to the top-level switch at SkullSpace, and has been assigned the IP 206.220.196.62.

Only three services are exposed to the Internet:

1. SSH
2. VPN
3. HTTPS

All other incoming traffic is blocked.

VMs

The VMs exist in the 10.255.0.0/16 subnet, with 10.255.0.1 assigned to the eth-vms adapter. All IP addresses in this range are statically assigned. This range was chosen because it is the least likely to conflict with a user's home network or other VPN that they are using.

VMs are permitted to receive connections on a case-by-case basis, as determined by the author of the challenge the VM is running. By default, all incoming connections to the VM network from the VPN and Wifi networks are blocked.

VMs have limited access to the Internet for the exclusive purpose of pulling down updates. The gateway maintains a whitelist of hostname:port pairs that are permitted from the VM network.

Our assumption is that the VMs are not in our control, and may be acting on the direction of anyone on the VPN or Wifi networks.

VPN

When a user wishes to access the DangerZone from the Internet, the web interface must be used to generate an OpenVPN certificate. VPN users are statically assigned addresses in the 10.1.0.0/16 range. The adapter tun0 has been assigned the IP 10.1.0.1.

The VPN network is never permitted to access anything other than the Gateway's VPN adapter and the VM network. Said another way, the VPN network may never talk to the Internet or the Wifi network.

We absolutely do not trust anything that comes out of the VPN.

This network never accepts incoming connections.

Wifi

When a user accesses the Wifi network, they will get an dynamically-assigned IP from a DHCP server in the 10.0.0.0/16 subnet which should be good for a week. The gateway's eth-wifi adapter is connected to this network, in fact it has a direct connection to the access point, and is assigned the IP 10.0.0.1. This address range was assigned to the Wifi network because it is the most likely to conflict with a user's home network, and when they're at SkullSpace we know it's not going to conflict.

Users connected over to the Wifi network will be at our physically at (or outside) our hackespace, and likely not connected over ethernet. This means that we need to give them access to the Internet, because they won't have another way to get to it. Users on the Wifi network should have unrestricted access to the Internet, just like if they were our non-DangerZone wifi.

This network never accepts incoming connections.

Subnets

Name	Range
VMs
VPN
Wifi

Adapters

Name	IP	Services
eth-pub	206.220.196.62	SSH, VPN, HTTPS
eth-vms	10.255.0.1/16
eth-wifi	10.0.0.1/16	HTTPS
tun0	10.1.0.1/16	HTTPS

Filtering

From	To	Allowed?	Notes
Internet	Gateway	Partially	SSH, VPN, HTTPS
Internet	VMs	No	Protect our infrastructure.
Internet	VPN	No	Protect our users.
Internet	Wifi	No	Protect our users.
Gateway	Internet	Yes	Useful for administration.
Gateway	VMs	Partial	Whitelist of host:port pairs.
Gateway	VPN	No	Protect our users.
Gateway	Wifi	No	Protect our users.
VMs	Internet	Partially	Whitelist of host:port pairs.
VMs	Gateway	No	No reason for it.
VMs	VPN	No	Protect our users.
VMs	Wifi	No	Protect our users.
VPN	Internet	No	Don't want remote users routing Internet traffic through us.
VPN	Gateway	Partially	HTTPS
VPN	VMs	Partially	Whitelist of host:port pairs as needed by the level.
VPN	VPN	No	Protect our users.
VPN	Wifi	No	Protect our users.
Wifi	Internet	Yes	Users will have no other method to access the Internet.
Wifi	Gateway	Partially	HTTPS
Wifi	VMs	Partially	Whitelist of host:port pairs as needed by the level.
Wifi	VPN	No	Protect our users.
Wifi	Wifi	Yes	Internal to the access point, we can't control.