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This file documents the next steps to take after installation of the
Debian package, and also contain some notes specific to the Debian
packaging which are not also in the manual.
* Adding a Client Password to the Server
The server must be given a password to give back to the client on
boot time. This password must be a one which can be used to unlock
the root file system device. On the *client*, run this command:
mandos-keygen --password
It will prompt for a password and output a config file section.
This output should be copied to the Mandos server and added to the
file "/etc/mandos/clients.conf" there.
* Testing that it Works (Without Rebooting)
After the server has been started with this client's key added, it
is possible to verify that the correct password will be received by
this client by running the command, on the client:
MANDOSPLUGINHELPERDIR=/usr/lib/$(dpkg-architecture \
-qDEB_HOST_MULTIARCH)/mandos/plugin-helpers \
/usr/lib/$(dpkg-architecture -qDEB_HOST_MULTIARCH \
)/mandos/plugins.d/mandos-client \
--pubkey=/etc/keys/mandos/pubkey.txt \
--seckey=/etc/keys/mandos/seckey.txt \
--tls-privkey=/etc/keys/mandos/tls-privkey.pem \
--tls-pubkey=/etc/keys/mandos/tls-pubkey.pem; echo
This command should retrieve the password from the server, decrypt
it, and output it to standard output. There it can be verified to
be the correct password, before rebooting.
* Emergency Escape
If it ever should be necessary, the Mandos client can be temporarily
prevented from running at startup by passing the parameter
"mandos=off" to the kernel.
* Specifying a Client Network Interface
At boot time the network interfaces to use will by default be
automatically detected. If this should result in incorrect
interfaces, edit the DEVICE setting in the
"/etc/initramfs-tools/initramfs.conf" file. (The default setting is
empty, meaning it will autodetect the interfaces.) *If* the DEVICE
setting is changed, it will be necessary to update the initrd image
by running this command:
(For initramfs-tools:)
update-initramfs -k all -u
(For dracut:)
dpkg-reconfigure dracut
The device can also be overridden at boot time on the Linux kernel
command line using the sixth colon-separated field of the "ip="
option; for exact syntax, read the documentation in the file
"/usr/share/doc/linux-doc-*/Documentation/filesystems/nfs/nfsroot.txt",
available in the "linux-doc-*" package.
Note that since the network interfaces are used in the initial RAM
disk environment, the network interfaces *must* exist at that stage.
Thus, an interface can *not* be a pseudo-interface such as "br0" or
"tun0"; instead, only real interfaces (such as "enp1s0" or "eth0")
can be used. This can be overcome by writing a "network hook"
program to create an interface (see mandos-client(8mandos)) and
placing it in "/etc/mandos/network-hooks.d", from where it will be
copied into the initial RAM disk. Example network hook scripts can
be found in "/usr/share/doc/mandos-client/examples/network-hooks.d".
* User-Supplied Plugins
Any plugins found in "/etc/mandos/plugins.d" will override and add
to the normal Mandos plugins. When adding or changing plugins, do
not forget to update the initial RAM disk image:
(For initramfs-tools:)
update-initramfs -k all -u
(For dracut:)
dpkg-reconfigure dracut
* Do *NOT* Edit "/etc/crypttab"
It is NOT necessary to edit "/etc/crypttab" to specify
"/usr/lib/mandos/plugin-runner" as a keyscript for the root file
system; if no keyscript is given for the root file system, the
Mandos client will be the new default way for getting a password for
the root file system when booting.
* Non-local Connection (Not Using ZeroConf)
If the "ip=" kernel command line option is used to specify a
complete IP address and device name, as noted above, it then becomes
possible to specify a specific IP address and port to connect to,
instead of using ZeroConf. The syntax for doing this is
"mandos=connect:<IP_ADDRESS>:<PORT_NUMBER>" on the kernel command
line.
For very advanced users, it is possible to specify "mandos=connect"
on the kernel command line to make the system only set up the
network (using the data in the "ip=" option) and not pass any extra
"--connect" options to mandos-client at boot. For this to work,
"--options-for=mandos-client:--connect=<ADDRESS>:<PORT>" needs to be
manually added to the file "/etc/mandos/plugin-runner.conf" or, if
dracut is used with systemd, the "--connect=<ADDRESS>:<PORT>"
options needs to be added to an environment variable in an override
file for the "ask-password-mandos" service, as detailed in the file
"/usr/lib/dracut/modules.d/90mandos/ask-password-mandos.service".
* Diffie-Hellman Parameters
On installation, a file with Diffie-Hellman parameters,
/etc/keys/mandos/dhparams.pem, will be generated and automatically
installed into the initial RAM disk image and also used by the
Mandos Client on boot. If different parameters are needed for
policy or other reasons, simply replace the existing dhparams.pem
file and update the initial RAM disk image.
-- Teddy Hogeborn <teddy@recompile.se>, Sun, 8 Sep 2024 02:09:20 +0200
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