On Tue, Oct 30, 2012 at 12:35 PM, Doug Burks <[email protected]> wrote:

> I'd like to use netsniff-ng to replace daemonlogger in my Security
> Onion distribution:
> http://securityonion.blogspot.com

Cool, happy to hear! :)

> So far, I've got netsniff-ng 0.5.7 packaged in our Ubuntu Launchpad PPA:
> https://launchpad.net/~securityonion/+archive/test/+sourcepub/2761680/+listing-archive-extra

Probably, you're better off taking a current snapshot from the Git.

> Now I need to update our scripts to run netsniff-ng with the same
> specifications as daemonlogger.  We currently run daemonlogger as
> follows:
> daemonlogger -u sguil -g sguil -i $INTERFACE -f
> /etc/nsm/$HOSTNAME-$INTERFACE/bpf-pcap.conf -l
> /nsm/sensor_data/$HOSTNAME-$INTERFACE/dailylogs/$DATE -n snort.log -s
> 134217728
>
> Let's look at each of these options:
>
> -u sguil -g sguil
> According to the netsniff-ng FAQ, netsniff-ng must be run as root, so
> this is not possible.

You can also run it as a user. Have a look at the latest INSTALL file:
     https://github.com/gnumaniacs/netsniff-ng/blob/master/INSTALL#L81

> -i $INTERFACE
> This should be the same option in netsniff-ng.

Yep. or "--in" works as well.

> -f /etc/nsm/$HOSTNAME-$INTERFACE/bpf-pcap.conf
> This should be the same option in netsniff-ng, but my understanding is
> that I'll need to convert my "human-readable" bpf-pcap.conf using
> "tcpdump -dd"?

Yes, it you want to use filters and bpf-pcap.conf contains
tcpdump-like filters, run them through "tcpdump -dd <my filter>" >
out.ops and then pass out.ops to netsniff-ng via "--filter out.ops".
That's it; netsniff-ng will then automatically enable the BPF JIT if
it's available in your kernel. This feature translates BPF filters
into architecture optimized machine opcodes within the kernel.

> -l /nsm/sensor_data/$HOSTNAME-$INTERFACE/dailylogs/$DATE
> In netsniff-ng, looks like I'll use the -o option to specify the
> output directory.

Yes, e.g. "netsniff-ng --in eth0 --out /opt/probe/ -s --interval 30 -b
0" would create a new pcap file every 30secs in the /opt/probe/
folder.

> -n snort.log
> This makes daemonlogger name the files in the output directory
> snort.log.$TIMESTAMP.  Is there an equivalent option in netsniff-ng?

No, currently there is no prefix option. If you like feel free to hack
the code, it should actually not be too difficult.

> -s 134217728
> This configures daemonlogger to rotate to a new pcap file when it
> reaches 129MB.  Is there an equivalent option in netsniff-ng?

No, we only rotate if a specified interval in seconds runs out.

> Thanks in advance for any assistance!

Also have a look into
https://github.com/gnumaniacs/netsniff-ng/tree/master/Documentation

It should address quite a lot of things and is more up-2-date than the
faq. For everything else, the mailing list of course. ;)

Thanks,

Daniel

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