PAM_DUO(8)

NAME
pam_duo - PAM module for Duo authentication

SYNOPSIS
pam_duo.so [conf=<FILENAME>]

DESCRIPTION
pam_duo provides secondary authentication (typically after successful password-based authentication) through the Duo authentication service.

OPTIONS
PAM module configuration options supported:

conf
    Specify an alternate configuration file to load. Default is /etc/duo/pam_duo.conf

debug
    Debug mode; send log messages to stderr instead of syslog.

CONFIGURATION
The INI-format configuration file must have a “duo” section with the following options:

host
    Duo API host (required).

ikey
    Duo integration key (required).

skey
    Duo secret key (required).

groups
    If specified, Duo authentication is required only for users whose primary group or supplementary group list matches one of the space-separated pattern-lists (see PATTERNS below).

failmode
    On service or configuration errors that prevent Duo authentication, fail “safe” (allow access) or “secure” (deny access). Default is “safe”.

pushinfo
    Send command to be approved via Duo Push authentication. Default is “no”.

http_proxy
    Use the specified HTTP proxy, same format as the HTTP_PROXY environment variable.

autopush
    Automatically send a login request to the first factor (usually push), instead of prompting the user. Default is "no".

prompts
    Set the maxiumum number of prompts pam_duo will show before denying access. Default is 3.

fallback_local_ip
    If unable to detect the authorizing user's IP address, fallback on the server's IP. Default is "no".

send_gecos
    Instead of using the unix username, send Duo the contents of the GECOS field from /etc/passwd. Default is "no".

An example configuration file:

    [duo]
    host = api-deadbeef.duosecurity.com
    ikey = SI9F...53RI
    skey = 4MjR...Q2NmRiM2Q1Y
    pushinfo = yes
    autopush = yes

Other authentication restrictions may be implemented using pam_listfile(8), pam_access(8), etc.

PATTERNS
A pattern consists of zero or more non-whitespace characters, ‘*’ (a wildcard that matches zero or more characters), or ‘’? (a wildcard that matches exactly one character).

A pattern-list is a comma-separated list of patterns. Patterns within pattern-lists may be negated by preceding them with an exclamation mark (‘’)!. For example, to specify Duo authentication for all users (except those that are also admins), and for guests:

    groups = users,!wheel,!*admin guests

FILES

/etc/duo/pam_duo.conf
    Default configuration file path

AUTHORS
pam_duo was written by Duo Security <support@duosecurity.com>

NOTES
When used with OpenSSH's sshd(8), only PAM-based authentication can be protected with this module; pubkey authentication bypasses PAM entirely. OpenSSH's PAM integration also does not honor an interactive pam_conv(3) conversation, prohibiting real-time Duo status messages (such as during voice callback).