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Ubuntu - PAM - Configure PAM
The main configuration file for PAM is /etc/pam.conf and the /etc/pam.d/ directory contains the PAM configuration files for each PAM-aware application/services.
PAM will ignore the file if the directory exists.
The syntax for the main configuration file is as follows.
service type control-flag module module-arguments
where:
- service: actual application name.
- type: module type/context/interface.
- control-flag: indicates the behavior of the PAM-API should the module fail to succeed in its authentication task.
- module: the absolute filename or relative pathname of the PAM.
- module-arguments: space separated list of tokens for controlling module behavior.
The file is made up of a list of rules written on a single line.
You can extend rules over multiple lines using the “\” escape character. For example:
aaa \ bbb
The format of each rule is a space separated collection of tokens (the first three are case-insensitive).
Comments are preceded with “#” marks and extend to the next end of line.
Syntax of PAM config files
The syntax of each file in /etc/pam.d/ is similar to that of the main file and is made up of lines of the following form:
type control-flag module module-arguments
This is a example of a rule definition (without module-arguments) found in the /etc/pam.d/sshd file, which disallows non-root logins when /etc/nologin exists:
account required pam_nologin.so