Traffic from the management network is not allowed except for specific
services. NTP is required of course, for time synchronization with the
pyrocufflink.blue domain controllers. RADIUS is necessary for WiFi
authentication, which is also handled by the DCs.
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.
Marking packets matching port-forwarding rules, and then allowing
traffic carrying that mark did not seem to work well. Often, packets
seemed to get dropped for no apparent reason, and outside connections to
NAT'd services was sometimes slow as a result. Explicitly listing every
destination host/port in the `forward` table seems to resolve this
issue.
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.
`dhcpcd` needs to start after the `network` service has started, as the
latter creates the interfaces to which the former needs to delegate IPv6
prefixes.
Dustin