[PATCH] Add auditd listener and remote audit protocol

[DJ Delorie]

> What I'm getting is that in addition to kernel-generated local events
> the auditd would also receive signals as well as tcp-based events from
> other sources. Would this be the way of implementing multi-source audit
> aggregation or is it something different?

The net result is to aggregate audit logs from many systems onto one
central audit server.  Remote audit messages have the new "node=" tag
on them so you know where they came from.

I.e. you configure audisp-remote.conf like this:

remote_server = 10.2.3.4
port = 1237

And the central server (10.2.3.4 in this example) like this:

tcp_listen_port = 1237

And then the client sends all audit messages to the server, where
they're logged to disk.

This is similar to centralized syslog logging.

The event loop change I linked to is a neccessary design change
prerequisite to this one, since the listener adds (potentially) many
descriptors which will need to be serviced.  The loop now services
four types of events: local signals, local netlink, the listen socket
(for new connections), and client sockets (for incoming audit
messages).