The gateway device is now monitored by Zabbix. Adding it to the *zabbix*
group ensures that the Zabbix agent is installed and configured
correctly.
Because the *zabbix-agent* role has a task to configure FirewallD, the
`host_uses_firewalld` variable needs to be set to `false` for *gw0*,
since it does not use FirewallD.
The `gitea_root_url` variable is used to configure the root URL for
Gitea, which is in turn used to generate HTTP/HTTPS "clone" links for
Git repositories. If this value is not set, the default is used, which
does not work since the application is behind a reverse proxy.
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.
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