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=== pam_u2f ===
=== pam_u2f ===


The `pam_u2f` module implements the U2F (universal second factor) protocol. The protocol was initially developed by Yubico, Google and NXP and is nowadays hosted as an open-standard by the FIDO Alliance. All current and most legacy Yubikeys support the U2F protocol making this the preferred way to use Yubikeys for user login.  
The <code>pam_u2f</code> module implements the U2F (universal second factor) protocol. The protocol was initially developed by Yubico, Google and NXP and is nowadays hosted as an open-standard by the FIDO Alliance. All current and most legacy Yubikeys support the U2F protocol making this the preferred way to use Yubikeys for user login.  


Use this page to check whether your Yubikey supports '''FIDO U2F''' before starting: https://www.yubico.com/products/identifying-your-yubikey/
Use this page to check whether your Yubikey supports '''FIDO U2F''' before starting: https://www.yubico.com/products/identifying-your-yubikey/
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1. Connect your Yubikey
1. Connect your Yubikey


2. Create an authorization mapping file for your user. The authorization mapping file is like `~/.ssh/known_hosts` but for Yubikeys.
2. Create an authorization mapping file for your user. The authorization mapping file is like <code>~/.ssh/known_hosts</code> but for Yubikeys.


# <code>nix-shell -p pam_u2f</code>
# <code>nix-shell -p pam_u2f</code>
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3. Verify that `~/.config/Yubico/u2f_keys` contains one line in the following style:
3. Verify that <code>~/.config/Yubico/u2f_keys</code> contains one line in the following style:


<syntaxHighlight>
<syntaxHighlight>
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See chapter ''Test PAM configuration'' an the end of this page.
See chapter ''Test PAM configuration'' an the end of this page.
6. (optional) Only allow Yubikey for login and sudo authentication
If you don't want to be able to use your password to login to your user account or access sudo, you can modify the pam service as follows.
{{Warning|Be careful, losing your Yubikey will make it impossible to sign in with this configuration.}}<syntaxhighlight lang="nixos">
  security.pam.services = {
    login = {
      u2fAuth = true;
      unixAuth = false;
    };
    sudo = {
      u2fAuth = true;
      unixAuth = false;
    };
  };
</syntaxhighlight>


=== yubico-pam ===
=== yubico-pam ===


The `yubico-pam` module uses a OTP (one time password) challenge response to authenticate users.
The <code>yubico-pam</code> module uses a OTP (one time password) challenge response to authenticate users.


Use this page to check whether your Yubikey supports '''Yubico OTP''' before starting: https://www.yubico.com/products/identifying-your-yubikey/
Use this page to check whether your Yubikey supports '''Yubico OTP''' before starting: https://www.yubico.com/products/identifying-your-yubikey/


You can enable challenge-response logins with the following commands:
You'll first need to install the necessary udev packages to your NixOS configuration:<syntaxhighlight lang="nix">
services.udev.packages = [ pkgs.yubikey-personalization ];
</syntaxhighlight>You can program the Yubikey for challenge-response on slot 2 and setup the current user for logon:
# <code>nix-shell -p yubico-pam -p yubikey-manager</code>
# <code>ykman otp chalresp --touch --generate 2</code>
# <code>ykpamcfg -2 -v</code>
Finally, you can enable challenge-response logins with the following commands:


'''1.)'''
'''1.)'''
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to get the serial code and enter it into <code>yubico.id = [ "12345678" ];</code>
to get the serial code and enter it into <code>yubico.id = [ "12345678" ];</code>


'''WARNING, ignoring step 1 is considered insecure, any user could just plugin a yubikey and gain root access!'''
{{warning|1=Ignoring step 1 is considered insecure, any user could just plugin a yubikey and gain root access!}}


'''2.)'''<syntaxHighlight lang=nix>
'''2.)'''<syntaxHighlight lang=nix>
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};
};
</syntaxHighlight>
</syntaxHighlight>
You'll also need to program the Yubikey for challenge-response on slot 2 and setup the current user for logon:
# <code>nix-shell -p yubico-pam -p yubikey-manager</code>
# <code>ykman otp chalresp --touch --generate 2</code>
# <code>ykpamcfg -2 -v</code>




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</syntaxHighlight>
</syntaxHighlight>


Please note that the PCSC-Lite daemon [https://ludovicrousseau.blogspot.com/2019/06/gnupg-and-pcsc-conflicts.html sometimes conflicts] with gpg-agent.
Please note that the PCSC-Lite daemon [https://ludovicrousseau.blogspot.com/2019/06/gnupg-and-pcsc-conflicts.html sometimes conflicts] with gpg-agent. This can be solved by putting the line <code>disable-ccid</code> into <code>~/.gnupg/scdaemon.conf</code>. There is also a [https://nix-community.github.io/home-manager/options.xhtml#opt-programs.gpg.scdaemonSettings Home Manager Option] for that.


== OTP ==
== OTP ==


In order to manage OTP keys, you should install the <code>yubioath-desktop</code> package in your profile.
In order to manage OTP keys, you should install the <code>yubioath-flutter</code> package in your profile.
This application will also require both the udev rules as well as pcscd enabled.
This application will also require both the udev rules as well as pcscd enabled.


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* [https://rzetterberg.github.io/yubikey-gpg-nixos.html GPG-keys for SSH authentication on NixOS]
* [https://rzetterberg.github.io/yubikey-gpg-nixos.html GPG-keys for SSH authentication on NixOS]
* [[Yubikey_based_Full_Disk_Encryption_(FDE)_on_NixOS]]
* [[Yubikey_based_Full_Disk_Encryption_(FDE)_on_NixOS]]
[[Category:Cookbook]]
[[Category:Security]]
[[Category:Hardware]]
Retrieved from "https://wiki.nixos.org/wiki/Yubikey"