For the ones who use the Unix addon for extracting authentication events for Enterprise Security, and some events are not recognized, mainly on Ubuntu Linux (not tested on other distribs), here's the one I've added. Feel free to correct/complement them.
To be added in etc/apps/Splunk_TA_nix/local/props.conf:
EXTRACT-app_and_dest = ^\w+ +\d+ \d\d:\d\d:\d\d (?<dest>\w+) (?<app>\S+)\[\d+\]
EXTRACT-ssh_details = (?<vendor_action>Failed|Accepted) \w+ for (invalid user )*(?<user>\S+) from (?<src>\d+\.\d+\.\d+\.\d+) port (?<src_port>\d+)
EXTRACT-sudo_open_details = ^\w+ +\d+ \d\d:\d\d:\d\d \w+ (?<app>sudo): pam_unix\(sudo:session\): (?<vendor_action>session \w+) for user (?<user>\w+) by (?<src_user>\w+)
LOOKUP-action_for_linux_auth = nix_action_lookup vendor_action OUTPUTNEW action