Also document that `ProtectClock` blocks access to serial line.
I couldn't found out why this is the case,
but faxgetty complains about the device file
not being accessible with `ProtectClock=true`.
According to
https://github.com/NixOS/nixpkgs/pull/84556
this effort helps with cross-compilation.
This commit also renames a substituted variable `hylafax`
to `hylafaxplus` to permit substitution with `inherit`.
This commit adds the following
* the uucp user
* options for HylaFAX server to control startup and modems
* systemd services for HylaFAX server processes
including faxgettys for modems
* systemd services to maintain the HylaFAX spool area,
including cleanup with faxcron and faxqclean
* default configuration for all server processes
for a minimal working configuration
Some notes:
* HylaFAX configuration cannot be initialized with faxsetup
(as it would be common on other Linux distributions).
The hylafaxplus package contains a template spool area.
* Modems are controlled by faxgetty.
Send-only configuration (modems controlled by faxq)
is not supported by this configuration setup.
* To enable the service, one or more modems must be defined with
config.services.hylafax.modems .
* Sending mail *should* work:
HylaFAX will use whatever is in
config.services.mail.sendmailSetuidWrapper.program
unless overridden with the sendmailPath option.
* The admin has to create a hosts.hfaxd file somewhere
(e.g. in /etc) before enabling HylaFAX.
This file controls access to the server (see hosts.hfaxd(5) ).
Sadly, HylaFAX does not permit account-based access
control as is accepts connections via TCP only.
* Active fax polling should work; I can't test it.
* Passive fax polling is not supported by HylaFAX.
* Pager transmissions (with sendpage) are disabled by default.
I have never tested or used these.
* Incoming data/voice/"extern"al calls
won't be handled by default.
I have never tested or used these.
