The Management network (VLAN 10, 172.30.0.240/28) will be used for
communication with and configuration of network devices including
switches and access points. This keeps configuration separate from
normal traffic, and allows complete isolation of infrastructure devices.
This commit adjusts the firewall and networking configuration on dc0 to
host the Pyrocufflink remote access IPsec VPN locally instead of
forwarding it to the internal VPN server.
Connection Tracking does not work for DHCP messages, since many are
broadcast. As such, the firewall must explicitly allow datagrams
destined for the DHCP client port.
For internal services, particularly DNS, it is easier to use a ULA
prefix than rely exclusively on routed addresses, since these can change
relatively frequently.
The *filter* table is responsible for deciding which packets will be
accepted and which will be rejected. It has three chains, which classify
packets according to whether they are destined for the local machine
(input), passing through this machine (forward) or originating from the
local machine (output).
The *dch-gw* role now configures all three chains in this table. For
now, it defines basic rules, mostly based on TCP/UDP destination port:
* Traffic destined for a service hosted by the local machine (DNS, DHCP,
SSH), is allowed if it does not come from the Internet
* Traffic passing through the machine is allowed if:
* It is passing between internal networks
* It is destined for a host on the FireMon network (VPN)
* It was NATed to in internal host (marked 323)
* It is destined for the Internet
* Only DHCP, HTTP, and DNS are allowed to originate from the local
machine
This configuration requires an `internet_iface` variable, which
indicates the name of the network interface connected to the Internet
directly.
Dustin