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Yubico PAM module ----------------- The Yubico PAM module provides an easy way to integrate the Yubikey into your existing user authentication infrastructure. PAM is used by GNU/Linux, Solaris and Mac OS X for user authentication, and by other specialized applications such as NCSA !MyProxy. Status and Roadmap ------------------ The module is working for multi-user systems. The primary mode of operation is by doing online validation using a YubiKey validation service (such as the YubiCloud, or a private one configured using the 'url' parameter). In version 2.6, offline validation was also made possible through the use of HMAC-SHA1 Challenge-Response found in YubiKey 2.2 and later. This has introduced a currently mandatory dependency of libykpers-1 from the ykpersonalize package. The development community is co-ordinated via Google Code : http://code.google.com/p/yubico-pam/ The license for pam_yubico is the 2-clause BSD license, which is compatible with the Linux-PAM BSD/GPL license. See the file COPYING for more information. Building from Git ----------------- Skip to the next section if you are using an official packaged version. You may check out the sources using Git with the following command: ------ $ git clone git://github.com/Yubico/yubico-pam.git yubico-pam ------ This will create a directory 'yubico-pam'. Autoconf, automake and libtool must be installed to create a compilable source tree. Generate the build system using: ------ $ cd yubico-pam $ autoreconf --install ------ Building -------- You will need to have libykclient (ykclient.h, libykclient.so) and libpam-dev (security/pam_appl.h, libpam.so) installed. Get the ykclient library from: http://code.google.com/p/yubico-c-client/ It in turn requires Curl, which you need to have installed, and libyubikey. Get libyubikey from http://code.google.com/p/yubico-c/ The new Challenge-Response offline authentication requires libykpers-1 from the yubikey-personalization project : http://code.google.com/p/yubikey-personalization/ The build system uses Autoconf, to set up the build system run: ------ ./configure ------ Use --without-ldap to disable ldap support. Then build the code, run the self-test and install the binaries: ------ make check install ------ Ubuntu PPA ---------- There is an Ubuntu PPA (Private Package Archive) for yubico-pam that can be installed using the following commands on reasonably modern Ubuntu platforms : $ sudo add-apt-repository ppa:fredrikt/yubico-pam $ sudo apt-get update $ sudo apt-get install yubico-pam You will have to configure pam_yubico manually in /etc/pam.d/common-auth manually after installing. Configuration ------------- Install it in your PAM setup by adding a line to an appropriate file in /etc/pam.d/: ------ auth sufficient pam_yubico.so id=16 debug ------ and move pam_yubico.so into /lib/security/ (or wherever PAM modules live in your system) : ------ mv /usr/local/lib/security/pam_yubico.so /lib/security/ ------ For more information, see the project Wiki page. Supported PAM module parameters are: ------ "authfile": to indicate the location of the file that holds the mappings of Yubikey token IDs to user names. "id": to indicate your client identity. "key": to indicate your client key in base64 format. The client key is also known as API key, and provides integrity in the communication between the client (you) and the validation server. If you want to get one for use with the default YubiCloud service, visit this URL : https://upgrade.yubico.com/getapikey/ "debug": to enable debug output to stdout. "alwaysok": to enable all authentication attempts to succeed (aka presentation mode). "try_first_pass": Before prompting the user for their password, the module first tries the previous stacked module´s password in case that satisfies this module as well. "use_first_pass": The argument use_first_pass forces the module to use a previous stacked modules password and will never prompt the user - if no password is available or the password is not appropriate, the user will be denied access. "url": specify the URL template to use, this is set by calling yubikey_client_set_url_template, which defaults to: http://api.yubico.com/wsapi/verify?id=%d&otp=%s or http://api.yubico.com/wsapi/2.0/verify?id=%d&otp=%s depending on your version of yubico-c-client. "verbose_otp": This argument is used to show the OTP when it is entered, i.e. to enable terminal echo of entered characters. You are advised to not use this, if you are using two factor authentication because that will display your password on the screen. This requires the service using the PAM module to display custom fields. For example, OpenSSH requires you to configure "ChallengeResponseAuthentication no". "ldap_uri": specify the LDAP server URI (e.g. ldap://localhost). "ldapserver": specify the LDAP server host (default LDAP port is used). _Deprecated. Use "ldap_uri" instead._ "ldapdn": specify the dn where the users are stored (eg: ou=users,dc=domain,dc=com). "user_attr": specify the LDAP attribute used to store user names (eg:cn). "yubi_attr": specify the LDAP attribute used to store the Yubikey id. "capath": Path to a directory with SSL CA certs you trust. ------ If you are using "debug" you may find it useful to create a world-writable log file: ------ touch /var/run/pam-debug.log chmod go+w /var/run/pam-debug.log ------ Authorization Mapping Files --------------------------- A mapping must be made between the Yubikey token ID and the user ID it is attached to. There are two ways to do this, either centrally in one file, or individually, where users can create the mapping in their home directories. If the central authorization mapping file is being used, user home directory mappings will not be used and the opposite applies if user home directory mappings are being used, the central authorization mappings file will not be used. Central authorization mapping ----------------------------- Create a /etc/yubikey_mappings, the file must contain a user name and the Yubikey token ID separated by colons (same format as the passwd file) for each user you want to allow onto the system using a Yubikey. The mappings should look like this, one per line: ------ <user name>:<Yubikey token ID>:<Yubikey token ID>:…. <user name>:<Yubikey token ID>:<Yubikey token ID>:…. ------ Now add authfile=/etc/yubikey_mappings to your PAM configuration line, so it looks like: ------ auth sufficient pam_yubico.so id=16 authfile=/etc/yubikey_mappings ------ Individual authorization mapping by user ---------------------------------------- Each user creates a ~/.yubico/authorized_yubikeys file inside of their home directory and places the mapping in that file, the file must have only one line: ------ <user name>:<Yubikey token ID>:<Yubikey token ID> ------ This is much the same concept as the SSH authorized_keys file. Obtaining the Yubikey token ID (a.k.a. public ID) ------------------------------------------------- You can obtain the Yubikey token ID in two places. One is by removing the last 32 characters of any OTP generated with your Yubikey, the other is by using the modhex calculator located here : http://radius.yubico.com/demo/Modhex_Calculator.php Enter your Yubikey OTP and convert it, your Yubikey token ID is 12 digits and listed as: Modhex encoded: XXXXXXX Examples -------- If you want to use the Yubikey to authenticate you on linux console logins, add the following to the top of /etc/pam.d/login: ------ auth sufficient pam_yubico.so id=16 debug ------ Feedback -------- If you want to discuss anything related to the Yubico PAM module, please contact Simon Josefsson <email@example.com>.