Re: Strange portscan traffic with dest of 169.254.x.x

[Aaron Giuoco <agiuoco () yahoo com>]

Thanks for all of the comments.  I'm thinking about just suppressing those alerts to the 169.254.0.0/16 range.  The 
other strange thing about this that, something I failed to mention in my original post, is the volume of these alerts.  
It's not consistent across all of the machines.  Usually, there will be just one or two boxes out there that generate 
300-400 of these types of alerts over a 24-hour period.  The next closest machine is usually generating between 20 and 
50 alerts.  Then everything returns to normal.

For that reason, I think it might be something installed on those specific computers that is generating all of that 
traffic.  The traffic is probably harmless, but now I'm curious.  So I'm off to chase the wild goose!
:-)

AG

----- Original Message ----
From: Joel Esler <joel.esler () sourcefire com>
To: dhottinger () harrisonburg k12 va us
Cc: snort-users () lists sourceforge net
Sent: Monday, February 25, 2008 5:02:04 PM
Subject: Re: [Snort-users] Strange portscan traffic with dest of 169.254.x.x

CunningPike had it right.  When your machines can't find an IP (via  
DHCP, or whatever), they default to the 169.254.x.x range.

Since your machines were contacting ports 139:445, I am willing to bet  
that it's a Windows machine plugged into the network somewhere, (on  
the same broadcast domain as your Snort sensor), and can't DHCP itself  
for whatever reason.

My suggest is that you use Snort in sniffer mode like

#snort -vde 'net 169.254.x.x' look at the mac addresses.  See if that  
helps you out any.

Assigning these IPs should be the default behavior of both Windows and  
OSX.

Joel

On Feb 25, 2008, at 5:47 PM, dhottinger () harrisonburg k12 va us wrote:

> Quoting Aaron Giuoco <agiuoco () yahoo com>:
>
> > True.  But it is unusual to see so much traffic from 169.254 leaving
> > a computer that already has a network connection.
> >
> > I haven't been able to confirm whether the packets are related to
> > ActiveSync like Paul mentioned.  Thanks for the replies.  I'll try
> > to confirm whether or not ActiveSync is being used on these PCs or
> > not and post back.
> >
> > AG
> I missed part of this post.  However, I see lots of 169 traffic from
> my apple 10.4, 10.5 computers.  I think they use it for bonjour or
> entourage, which is a way to find printers, and other network  
> resources.
>
>
> -- 
> Dwayne Hottinger
> Network Administrator
> Harrisonburg City Public Schools
>
> "Everything should be made as simple as possible, but not simpler."
> -- Albert Einstein
>
>
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--
Joel Esler  joel.esler () sourcefire com





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