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Remote disk unlocking: Difference between revisions

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Simpler instructions for setting up tor
 
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If you want to unlock your computer remotely via SSH or even through Tor, and you are facing the probllem, that you can’t reach your computer before your computer is unlocked. Tor will help you to reach your computer, even during the boot process.
If you want to unlock your computer remotely via SSH or even through Tor, and you are facing the problem, that you can’t reach your computer before your computer is unlocked. Tor will help you to reach your computer, even during the boot process.


== Setup ==
== Setup ==
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<syntaxhighlight lang="bash">
<syntaxhighlight lang="bash">
# mkdir -p /etc/secrets/initrd
# ssh-keygen -t ed25519 -N "" -f /etc/secrets/initrd/ssh_host_ed25519_key
# ssh-keygen -t ed25519 -N "" -f /etc/secrets/initrd/ssh_host_ed25519_key
</syntaxhighlight>
</syntaxhighlight>


Enable SSH daemon in initrd≥
Enable SSH daemon in initrd


{{file|/etc/nixos/configuration.nix|nix|<nowiki>
{{file|/etc/nixos/configuration.nix|nix|<nowiki>
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     postCommands = ''
     postCommands = ''
       # Automatically ask for the password on SSH login
       # Automatically ask for the password on SSH login
       echo 'cryptsetup-askpass || echo "Unlock was successful; exiting SSH session" && exit 1' \
       echo 'cryptsetup-askpass || echo "Unlock was successful; exiting SSH session" && exit 1'</nowiki> >> <nowiki>/root/.profile
        | tee /root/.profile
     '';
     '';
   };
   };
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Using systemd in initrd automatically continues the boot process after the target <code>/sysroot</code> is mounted.
Using systemd in initrd automatically continues the boot process after the target <code>/sysroot</code> is mounted.
=== Wireguard in initrd ===
Considering you've already enabled the ssh daemon, configured networking (for example with DHCP or static IP) and configured an unlocking command, following additional snippet will enable [[WireGuard]] connectivity to a remote peer while in initrd.<syntaxhighlight lang="nix">
boot.initrd.availableKernelModules = [ "r8169" "wireguard" ];
boot.initrd.systemd = {
  enable = true;
  network = {
    netdevs."30-wg-initrd" = {
      netdevConfig = {
        Kind = "wireguard";
        Name = "wg-initrd";
      };
      wireguardConfig = { PrivateKeyFile = "/etc/secrets/30-wg-initrd.key"; };
      wireguardPeers = [{
        AllowedIPs = [ "10.250.0.1/32" ];
        PublicKey = "wUE//Lwi8DZVIvAjIAtMoy+ku+hJ0w28H7ofySwAJRk=";
        Endpoint = "198.51.100.1:51821";
        PersistentKeepalive = 25;
      }];
    };
    networks."30-wg-initrd" = {
      name = "wg-initrd";
      addresses = [{ Address = "10.250.0.2/24"; }];
    };
  };
};
boot.initrd.secrets."/etc/secrets/30-wg-initrd.key" = "/etc/wireguard/private-key";
</syntaxhighlight>First generate a private und public key pair as mentioned in the WireGuard article. Reference the private key in <code>boot.initrd.secrets</code>, in this exmaple <code>/etc/wireguard/private-key</code>. Put the <code>PublicKey</code> of the remote peer into the <code>wireguardPeers</code> array.
Configure the IP addresses used by your initrd peer (<code>10.250.0.2</code>) and the remote peer (<code>10.250.0.1</code>). Also specify the IP and port of the remote peer in <code>Endpoint</code>, in our example <code>198.51.100.1:51821</code>. The remote peer also needs to know address configuration and the public key of the initrd peer.
Last but not least add the <code>wireguard</code> kernel module to <code>boot.initrd.availableKernelModules</code> beside the module required by your network device.


=== Tor in initrd ===
=== Tor in initrd ===


An example with an ssh server listening at a tor hidden service address can be found at [https://cgit.euer.krebsco.de/stockholm/tree/krebs/2configs/tor/initrd.nix?id=9919cb25912dfcc50881239f95494dd2f8e7b858 krebs/2configs/tor/initrd.nix in stockholm]
An example with an ssh server listening at a tor hidden service address can be found at [https://cgit.euer.krebsco.de/makefu/stockholm/src/commit/9b1008814e981dc01afe9ee7446322ad512c1d72/krebs/2configs/tor/initrd.nix krebs/2configs/tor/initrd.nix in stockholm]


==== Prepare the Onion ID ====
==== Prepare the Onion ID ====
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* <code>hs_ed25519_secret_key</code>
* <code>hs_ed25519_secret_key</code>


To create these files, you have to run tor once, with a dummy configuration.
To create these files:
 
$ nix-shell -p mkp224o --command "mkp224o-donna snow -n 1 -d ."
<pre>DataDirectory /tmp/my-dummy.tor/
set workdir: ./
SOCKSPort 127.0.0.1:10050 IsolateDestAddr
nixuum6flqthv6ar52j5e2ldulylfsfgezykeg37iy74kqowcp5gxfyd.onion
SOCKSPort 127.0.0.1:10063
The files you need are in the <code>*.onion</code> directory:
HiddenServiceDir /home/tony/tor/onion
$ ls *.onion
HiddenServicePort 1234 127.0.0.1:1234</pre>
hostname  hs_ed25519_public_key  hs_ed25519_secret_key
Let’s asume you created this file in <code>/home/tony/tor/tor.rc</code>.
 
Verify that everything is <code>tor.rc</code> awesome, by running <code>tor -f /home/tony/tor/tor.rc --verify-config</code>. If you don’t see any errors, just run <code>tor -f /home/tony/tor/tor.rc</code>.
 
You will get some output like this.
 
<pre>May 21 18:38:39.000 [notice] Bootstrapped 80% (ap_conn): Connecting to a relay to build circuits
May 21 18:38:39.000 [notice] Bootstrapped 85% (ap_conn_done): Connected to a relay to build circuits
May 21 18:38:39.000 [notice] Bootstrapped 89% (ap_handshake): Finishing handshake with a relay to build circuits
May 21 18:38:39.000 [notice] Bootstrapped 90% (ap_handshake_done): Handshake finished with a relay to build circuits
May 21 18:38:39.000 [notice] Bootstrapped 95% (circuit_create): Establishing a Tor circuit
May 21 18:38:40.000 [notice] Bootstrapped 100% (done): Done</pre>
Hit <code>Ctrl-C</code> and the files you need, should be in <code>/home/tony/tor/onion</code>.


==== Setup Tor ====
==== Setup Tor ====
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<syntaxhighlight lang="nix"># copy your onion folder
<syntaxhighlight lang="nix"># copy your onion folder
boot.initrd.secrets = {
boot.initrd.secrets = {
   "/etc/tor/onion/bootup"; = /home/tony/tor/onion; # maybe find a better spot to store this.
   "/etc/tor/onion/bootup" = /home/tony/tor/onion; # maybe find a better spot to store this.
};
};


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=== Enable Wifi in initrd ===
=== Enable Wifi in initrd ===
Following example configuration by [https://discourse.nixos.org/t/wireless-connection-within-initrd/38317/13 @loutr] enables wifi connections inside initrd. Replace interface name <code>wlp0s20f0u4</code> with the name of your wifi adapter. Depending on your wifi device, you might need to add different kernel modules.<syntaxhighlight lang="nix">
Following example configuration by [https://discourse.nixos.org/t/wireless-connection-within-initrd/38317/13 @loutr] enables wifi connections inside initrd. Replace interface name <code>wlp0s20f0u4</code> with the name of your wifi adapter. Depending on your wifi device, you might need to add different kernel modules.<syntaxhighlight lang="nix">
boot.initrd = {
{
  # crypto coprocessor and wifi modules
  boot.initrd = {
  availableKernelModules = [ "ccm" "ctr" "iwlmvm" "iwlwifi" ];
    # crypto coprocessor and wifi modules
    availableKernelModules = [
      "ccm"
      "ctr"
      "iwlmvm"
      "iwlwifi"
    ];


  systemd = {
    systemd = {
    enable = true;
      enable = true;


    packages = [ pkgs.wpa_supplicant ];
      packages = [ pkgs.wpa_supplicant ];
    initrdBin = [ pkgs.wpa_supplicant ];
      initrdBin = [ pkgs.wpa_supplicant ];
    targets.initrd.wants = [ "wpa_supplicant@wlp0s20f0u4.service" ];
      targets.initrd.wants = [ "wpa_supplicant@wlp0s20f0u4.service" ];


    # prevent WPA supplicant from requiring `sysinit.target`.
      # prevent WPA supplicant from requiring `sysinit.target`.
    services."wpa_supplicant@".unitConfig.DefaultDependencies = false;
      services."wpa_supplicant@".unitConfig.DefaultDependencies = false;


    users.root.shell = "/bin/systemd-tty-ask-password-agent";
      users.root.shell = "/bin/systemd-tty-ask-password-agent";


    network = {
      network = {
      enable = true;
      networks."10-wlan" = {
        matchConfig.Name = "wlp0s20f0u4";
        networkConfig.DHCP = "yes";
      };
      ssh = {
         enable = true;
         enable = true;
         port = 22;
         networks."10-wlan" = {
        hostKeys = [ "/etc/ssh/ssh_host_ed25519_key" ];
          matchConfig.Name = "wlp0s20f0u4";
         authorizedKeys = default.user.openssh.authorizedKeys.keys;
          DHCP = "yes";
         };
       };
       };
    };
    network.ssh = {
      enable = true;
      port = 22;
      hostKeys = [ "/etc/ssh/ssh_host_ed25519_key" ];
      authorizedKeys = default.user.openssh.authorizedKeys.keys;
     };
     };


     secrets."/etc/wpa_supplicant/wpa_supplicant-wlp0s20f0u4.conf" = /root/secrets/wpa_supplicant.conf;
     secrets."/etc/wpa_supplicant/wpa_supplicant-wlp0s20f0u4.conf" = /root/secrets/wpa_supplicant.conf;
   };
   };
</syntaxhighlight>The file <code>wpa_supplicat-wlp0s20f0u4.conf</code> is the wireless profile used by [[wpa_supplicant]] which will get copied into the initramfs.
}
</syntaxhighlight>The file <code>wpa_supplicant-wlp0s20f0u4.conf</code> is the wireless profile used by [[wpa_supplicant]] which will get copied into the initramfs.
[[Category:Server]]
[[Category:Server]]
[[Category:Cookbook]]
[[Category:Cookbook]]
Retrieved from "https://wiki.nixos.org/wiki/Remote_disk_unlocking"