Remote logging with autitd

Thu Nov 13 22:23:59 UTC 2014

Hi Steve (and others),

Many thanks for the presentation, it has been very helpful. I have started to work on a simple plugin in Python, but I got a bit stuck again.
At the moment it just logs all data on STDIN to a file in /tmp.

Right now the system is set up such that on the client server the audit data gets sent to my central server using audisp + audisp-remote.
The central server receives the data using auditd, logs it /var/log/audit/audit.log and sends it to audisp, which in turn sends it to my plugin.
I can see  audit events from both my client and central server being written in /var/log/audit/audit.log, as expected. The two are easily extinguished by the node names. 

However, in my plugin I only  seems to receive data from the central (i.e. local) server... I draw this conclusion both because I see only one node name, and also because I generate TTY events on the client server only (and they show in /var/log/audit/audit.log as expected), and these do not show in the output from my plugin.
Is this the expected behaviour? Are plugins only supposed to receive the locally generated audit events?
If it is, is there a way to forward the remotely generated data to a plugin on the central server?

Any help would be much appreciated.

Many thanks,

Wouter 

From: woutervanverre at outlook.com
To: sgrubb at redhat.com; linux-audit at redhat.com
Subject: RE: Remote logging with autitd
Date: Sun, 2 Nov 2014 22:16:31 +0100

Hi Steve,

Many thanks for your response.
I will be reading the presentation and the examples in the tarball and go from there for implementing my processing plugin.

Regarding the logging to disk on the central server: 
I have node names set up for both servers now and am now getting the following behaviour:
   On the client server I can see the events being prefixed with node=Elephant in the log on that server. 
   On the central server I can see that local events are being prefixed with node=Mongoose.
   However, events that were sent to the central server by the client server show up in the central server's log with 
   node=localhost.localdomain. So it seems that the node information gets lost between the client and central server?

Would you have any idea why the node information is lost?

Many thanks,

Wouter

> From: sgrubb at redhat.com
> To: linux-audit at redhat.com
> CC: woutervanverre at outlook.com
> Subject: Re: Remote logging with autitd
> Date: Sun, 2 Nov 2014 13:12:53 -0500
> 
> On Saturday, November 01, 2014 10:49:24 PM Wouter van Verre wrote:
> > Hi all,
> > 
> > I am trying to set up logging using the audit framework, but I have some
> > questions about how the system works and how the components fit together.
> 
> This presentation is a pretty good overview, see slide 5:
> http://people.redhat.com/sgrubb/audit/audit_ids_2011.pdf
> 
> 
> > My use case is as follows:
> > * I would like to have one or more servers on my network capturing data,
> > including TTY sessions.
> > * I would then like to have these servers (the 'client servers') submit the
> > data to another server on the network (the 'central server').
> > * This central server would then write the incoming data to disk, and do
> > some processing on the data as well.
> > 
> > My current idea on how to implement this is to:
> > * Run auditd + audisp + audisp-remote on every client server.
> > * Use pam_tty_audit.so on every client server for the TTY logging.
> > * Run auditd on the central server to receive the data and write it to disk.
> > * Either implement my processing tool such that it can be used instead of
> > the dispatcher, or implement it as a plugin for audisp?
> 
> Sure. If necessary in realtime. That same presentation referenced about also 
> gives an introduction to the auparse library.
> 
>  
> > I'd love some feedback on whether this set up makes sense. In particular on
> > whether receiving the data with auditd on the central server is the best
> > way to go? And on which option is recommended for implementing the
> > processing tool? I would think that a custom plugin for audisp would be
> > best? If so, is there any documentation on how to go about implementing a
> > plugin for audisp that I could read?
> > 
> > I have already experimented with this set up a bit, and have come to the
> > conclusion that I am not sure how things work... I have implemented a
> > single client running auditd + audisp + audisp-remote with logging of TTY
> > session (using pam_tty_audit.so), and a central server running auditd (with
> > auditd configured to listen to port 60).
> > 
> > This seems to work to an extent:
> > * On the client server all the data is logged to /var/log/audit/audit.log
> > and I can see it there.
> > * On the client server I can run "aureport --tty" and I will see the TTY
> > session data represented more easily. 
> > * When I am on the central server I can run "aureport --tty" and see the TTY
> > session data for session on the client server. My conclusion based on this
> > is that the central server must be receiving and storing data properly?
> 
> Yes, that sounds right. I'd also mention that if you are doing central 
> logging, you need to tell audispd or auditd that you want the node name 
> prepended to the event so that at the aggregating server you can tell the 
> difference.
> 
> 
> > * However, when I look at /var/log/audit/audit.log on the central server I
> > can only see audit data for that server.
> 
> My first guess is that you don't have the client adding node information. That 
> makes it a lot clearer. You should able to search using --node to locate the 
> records from the client.
> 
> 
> > So my question is, where does the audit data from the client server get 
> stored?
> 
> In the aggregating server's directory.
> 
> > * When I connect a very simple program to the auditd daemon (instead of the
> > default dispatcher) it doesn't seem to receive any input at the moment, even
> > though "aureport --tty" is showing that the daemon has been receiving data
> > in the mean time...
> 
> The preferred way of adding analytical applications to make it am auditspd 
> plugin. You could make it a dispatcher if you want, but the interface is a bit 
> different. The audit tar ball should have an example program of both kinds.
> 
> -Steve

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