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README: Update with new inetd support.
Signed-off-by: Joachim Nilsson <troglobit@gmail.com>
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@@ -14,8 +14,9 @@ Table of Contents
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* [/etc/finit.d](#etcfinitd)
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* [Bootstrap](#bootstrap)
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* [Runlevels](#runlevels)
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* [Inetd](#inetd)
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* [Hooks, Callbacks & Plugins](#hooks-callbacks--plugins)
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* [Rebooting and Halting](#rebooting-and-halting)
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* [Rebooting & Halting](#rebooting--halting)
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* [Building](#building)
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* [Running](#running)
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* [Debugging](#debugging)
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@@ -59,11 +60,16 @@ Features
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**Process Supervision**
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Start, monitor and restart services if they fail.
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Start, monitor and restart processes (daemons) if they fail.
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**Inetd**
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Finit comes with an `inetd` server built-in. No need to maintain a
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seprate config file for services that you want to start on demand.
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**Runlevels**
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Runlevels is optional in Finit, but support for [SysV runlevels][5] is
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Runlevels are optional in Finit, but support for [SysV runlevels][5] is
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available if needed. All services in runlevel S(1) are started first,
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followed by the desired run-time runlevel. Runlevel S can be started in
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sequence by using `run [S] cmd`. Changing runlevels at runtime is done
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@@ -72,9 +78,10 @@ like any other init, e.g. <kbd>init 4</kbd>.
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**Plugins**
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Finit plugins can be either *boot hooks* into different stages of the
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boot process or *service callbacks*, or both. A basic set of plugins
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that extend and modify the basic behavior are bundled. See examples in
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the `plugins/` directory.
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boot process, *service callbacks*, or *pure extensions*. A plugin is a
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C file that compiles into a dynamic library that is loaded automatically
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by finit at boot. A basic set of plugins that extend and modify the
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basic behavior are bundled. See examples in the `plugins/` directory.
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Plugin capabilities:
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@@ -132,6 +139,12 @@ Syntax:
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--foreground or --no-background argument to most daemons to prevent
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them from forking off to the background.
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* `inetd SVC[@iface[:port]]/PROTO <wait|nowait> [LVLS] /path/to/daemon args -- desc`
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Launch daemon on demand on connection on SVC, as specified in the
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standard UNIX `/etc/services` file. With optional filtering for iface
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and possible custom port.
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* `runparts <PATH>`
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Call run-parts(8) on a directory other than default ``/etc/finit.d``
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@@ -142,28 +155,42 @@ Syntax:
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is prepended to file if the file is not found or an absolute path is
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not given
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* `tty [LVLS] <DEV | /bin/sh>`
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* `tty [LVLS] <DEV | /path/to/cmd [args]>`
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Start a getty on the given TTY device, in the given runlevels. When
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Start a getty on the given TTY device DEV, in the given runlevels. If
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no tty setting is given in `finit.conf`, or if `/bin/sh` is given as
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argument instead of a device path, a single shell is started on the
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default console. Useful for really bare-bones systems
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default console. Useful for really bare-bones systems.
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It is also possible to supply the full command line, with arguments,
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to your getty. In this case finit will simply use that command.
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See `finit.h` for the `#define GETTY` that is called, along with the
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default baud rate.
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* `console <DEV>`
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* `console <DEV | /path/to/cmd [args]>`
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Some embedded systems have a dedicated console port. This command
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tells finit to not start getty, but instead print a friendly message
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and wait for the user to activate the console with a key press before
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starting getty.
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Some embedded systems have a dedicated serial console/service port.
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This command tells finit to not start getty directly, since there may
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not be anyone there. To save RAM and CPU finit instead displays a
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friendly message and waits for the user to activate the console with a
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key press before starting getty. Finit also does some other magic and
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changes the process name to "console".
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Like the `tty` command, the `console` command can also be used to
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simply start a UNIX shell, e.g. `/bin/sh`.
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When running <kbd>make install</kbd> no default `/etc/finit.conf` will
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be installed since system requirements differ too much. Try out the
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Debian 6.0 example `/usr/share/doc/finit/finit.conf` configuration that
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is capable of service monitoring SSH, sysklogd, gdm and a console getty!
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Every `run`, `task`, `service`, or `inetd` can also list the privileges
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the `/path/to/cmd` should be executed with. Simply prefix the path with
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`[@USR[:GRP]]` like this:
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run [2345] @joe:users /usr/bin/logger "Hello world"
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/etc/finit.d
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------------
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@@ -255,6 +282,65 @@ Switching between runlevels can be done by calling init with a single
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argument, e.g. <kbd>init 5</kbd> switches to runlevel 5.
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Inetd
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-----
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A built-in *Internet Super Server* support was added in Finit v1.12,
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along with an internal `time` inetd service, RFC 868 (rdate). The
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latter is supplied as a plugin to illustrate how simple it is to extend
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finit with more internal inetd services.
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> Please note, not all UNIX daemons are prepared to run as inetd services.
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> In the example below `sshd` also need the command line argument `-i`.
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The inetd support in finit is quite advanced. Not only does it launch
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services on demand, it can do so on custom ports and also filter inbound
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traffic using a poor man's tcpwrappers. The syntax is very similar to
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traditional `/etc/inetd.conf`, yet keeping with the style of Finit:
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# Launch SSH on demand, in runlevels 2-5 as root
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inetd ssh/tcp nowait [2345] @root:root /usr/sbin/sshd -i
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A more advanced example:
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# Start sshd if inbound connection on eth0, port 222, or
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# inbound on eth1, port 22. Ignore on other interfaces.
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inetd ssh@eth0:222/tcp nowait [2345] /usr/sbin/sshd -i
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inetd ssh@eth1:22/tcp nowait [2345] /usr/sbin/sshd -i
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If eth0 is your Internet interface you may want to avoid using the
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default port. To run ssh on port 222, and all others on port 22:
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inetd ssh@eth0:222/tcp nowait [2345] /usr/sbin/sshd -i
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inetd ssh/tcp nowait [2345] /usr/sbin/sshd -i
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This actually adds a deny rule for eth0 on ssh/tcp, implicitly. You can
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even list the services in the reverse order with the same result:
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inetd ssh/tcp nowait [2345] /usr/sbin/sshd -i
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inetd ssh@eth0:222/tcp nowait [2345] /usr/sbin/sshd -i
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There is no specific deny syntax available yet, see the TODO file for
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more details on how this can be implemented.
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The `time.so` inetd plugin setup as folllows. Notice the keyword
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`internal` which applies to all built-in inetd services:
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inetd time/tcp nowait [2345] internal
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Then call `rdate` from a remote machine (or use localhost):
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rdate -p <IP>
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If you use `time/udp` you must use the standard rdate implementation and
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then call it with `rdate -up` to connect using UDP. Without the `-p`
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argument rdate will try to set the system clock. Please note that rdate
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has been deprecated by the NTP protocol and this plugin should only be
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used for testing or environments where NTP for some reason is blocked.
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Also, remember the UNIX year 2038 bug, or in the case of RFC 868 (and
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some NTP implementations), year 2036!
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Hooks, Callbacks & Plugins
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--------------------------
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@@ -278,13 +364,17 @@ plugins are available:
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* *resolvconf.so*: Setup necessary files for resolvconf at startup.
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* *tty.so*: Watches /dev, using inotify, for new device nodes (TTY's) to
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start/stop getty consoles on them on demand.
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* *tty.so*: Watches `/dev`, using inotify, for new device nodes (TTY's)
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to start/stop getty consoles on them on demand. Useful when plugging
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in a usb2serial converter to loging to your embedded device.
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* *urandom.so*: Setup random seed at startup.
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* *x11-common.so*: Setup necessary files for X-Window.
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* *time.so*: RFC 868 (rdate) plugin. Start as inetd service. Useful
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for testing inetd filtering -- BusyBox has an rdate (TCP) client.
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Usually you want to hook into the boot process once, simple hook plugins
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like `bootmisc.so` are great for that purpose. They are called at each
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hook point in the boot process, useful to insert some pre-bootstrap
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@@ -322,8 +412,8 @@ service, `SVC_START (1)` to start the service, or `SVC_RELOAD (2)` to
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have finit signal the process with `SIGHUP`.
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Rebooting and Halting
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---------------------
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Rebooting & Halting
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-------------------
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Finit handles `SIGUSR1` and `SIGUSR2` for reboot and halt, and listens
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to `/dev/initctl` so system reboot and halt commands should also work.
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