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:

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).