20.13. PAM Authentication
  This authentication method operates similarly to
  
   password
  
  except that it uses PAM (Pluggable
    Authentication Modules) as the authentication mechanism. The
    default PAM service name is
  
   postgresql
  
  .
    PAM is used only to validate user name/password pairs and optionally the
    connected remote host name or IP address. Therefore the user must already
    exist in the database before PAM can be used for authentication.  For more
    information about PAM, please read the
  
   
    Linux-PAM
   
   Page
  
  .
 
The following configuration options are supported for PAM:
- 
    
     pamservice
- 
    PAM service name. 
- 
    
     pam_use_hostname
- 
    Determines whether the remote IP address or the host name is provided to PAM modules through the PAM_RHOSTitem. By default, the IP address is used. Set this option to 1 to use the resolved host name instead. Host name resolution can lead to login delays. (Most PAM configurations don't use this information, so it is only necessary to consider this setting if a PAM configuration was specifically created to make use of it.)
Note
   If PAM is set up to read
   
    /etc/shadow
   
   , authentication
     will fail because the PostgreSQL server is started by a non-root
     user.  However, this is not an issue when PAM is configured to use
     LDAP or other authentication methods.