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A client key has been automatically created in /etc/keys/mandos. The
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next step is to run "mandos-keygen --password" to get a config file
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stanza to copy and paste into /etc/mandos/clients.conf on the Mandos
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Also, if some other network interface than "eth0" is used, it will be
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necessary to edit /etc/mandos/plugin-runner.conf to uncomment and
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change the line there. If this file is changed, it will be necessary
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to update the initrd image by doing "update-initramfs -k all -u".
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It is NOT necessary to edit /etc/crypttab to specify
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/usr/lib/mandos/plugin-runner as a keyscript for the root file system;
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if no keyscript is given for the root file system, the Mandos client
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will be the new default way for getting a password for the root file
1
This file documents the next steps to take after installation of the
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Debian package, and also contain some notes specific to the Debian
3
packaging which are not also in the manual.
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* Adding a Client Password to the Server
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The server must be given a password to give back to the client on
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boot time. This password must be a one which can be used to unlock
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the root file system device. On the *client*, run this command:
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mandos-keygen --password
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It will prompt for a password and output a config file section.
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This output should be copied to the Mandos server and added to the
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file "/etc/mandos/clients.conf" there.
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* Testing that it Works (Without Rebooting)
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After the server has been started with this client's key added, it
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is possible to verify that the correct password will be received by
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this client by running the command, on the client:
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MANDOSPLUGINHELPERDIR=/usr/lib/$(dpkg-architecture \
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-qDEB_HOST_MULTIARCH)/mandos/plugin-helpers \
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/usr/lib/$(dpkg-architecture -qDEB_HOST_MULTIARCH \
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)/mandos/plugins.d/mandos-client \
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--pubkey=/etc/keys/mandos/pubkey.txt \
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--seckey=/etc/keys/mandos/seckey.txt \
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--tls-privkey=/etc/keys/mandos/tls-privkey.pem \
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--tls-pubkey=/etc/keys/mandos/tls-pubkey.pem; echo
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This command should retrieve the password from the server, decrypt
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it, and output it to standard output. There it can be verified to
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be the correct password, before rebooting.
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If it ever should be necessary, the Mandos client can be temporarily
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prevented from running at startup by passing the parameter
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"mandos=off" to the kernel.
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* Specifying a Client Network Interface
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At boot time the network interfaces to use will by default be
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automatically detected. If this should result in incorrect
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interfaces, edit the DEVICE setting in the
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"/etc/initramfs-tools/initramfs.conf" file. (The default setting is
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empty, meaning it will autodetect the interfaces.) *If* the DEVICE
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setting is changed, it will be necessary to update the initrd image
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by running this command:
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(For initramfs-tools:)
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update-initramfs -k all -u
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dpkg-reconfigure dracut
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The device can also be overridden at boot time on the Linux kernel
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command line using the sixth colon-separated field of the "ip="
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option; for exact syntax, read the documentation in the file
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"/usr/share/doc/linux-doc-*/Documentation/filesystems/nfs/nfsroot.txt",
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available in the "linux-doc-*" package.
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Note that since the network interfaces are used in the initial RAM
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disk environment, the network interfaces *must* exist at that stage.
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Thus, an interface can *not* be a pseudo-interface such as "br0" or
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"tun0"; instead, only real interfaces (such as "enp1s0" or "eth0")
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can be used. This can be overcome by writing a "network hook"
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program to create an interface (see mandos-client(8mandos)) and
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placing it in "/etc/mandos/network-hooks.d", from where it will be
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copied into the initial RAM disk. Example network hook scripts can
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be found in "/usr/share/doc/mandos-client/examples/network-hooks.d".
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* User-Supplied Plugins
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Any plugins found in "/etc/mandos/plugins.d" will override and add
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to the normal Mandos plugins. When adding or changing plugins, do
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not forget to update the initial RAM disk image:
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(For initramfs-tools:)
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update-initramfs -k all -u
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dpkg-reconfigure dracut
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* Do *NOT* Edit "/etc/crypttab"
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It is NOT necessary to edit "/etc/crypttab" to specify
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"/usr/lib/mandos/plugin-runner" as a keyscript for the root file
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system; if no keyscript is given for the root file system, the
91
Mandos client will be the new default way for getting a password for
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the root file system when booting.
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* Non-local Connection (Not Using ZeroConf)
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If the "ip=" kernel command line option is used to specify a
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complete IP address and device name, as noted above, it then becomes
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possible to specify a specific IP address and port to connect to,
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instead of using ZeroConf. The syntax for doing this is
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"mandos=connect:<IP_ADDRESS>:<PORT_NUMBER>" on the kernel command
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For very advanced users, it is possible to specify simply
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"mandos=connect" on the kernel command line to make the system only
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set up the network (using the data in the "ip=" option) and not pass
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any extra "--connect" options to mandos-client at boot. For this to
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work, "--options-for=mandos-client:--connect=<ADDRESS>:<PORT>" needs
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to be manually added to the file "/etc/mandos/plugin-runner.conf".
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* Diffie-Hellman Parameters
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On installation, a file with Diffie-Hellman parameters,
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/etc/keys/mandos/dhparams.pem, will be generated and automatically
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installed into the initial RAM disk image and also used by the
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Mandos Client on boot. If different parameters are needed for
116
policy or other reasons, simply replace the existing dhparams.pem
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file and update the initial RAM disk image.
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-- Teddy Hogeborn <teddy@recompile.se>, Sun, 8 Sep 2024 02:09:20 +0200