On 20 Feb 2015, at 16:00, Donald S. Doyle <[email protected]> wrote:

> Hi,
> 
> I apologize for the lack of info:
> 
> ISP > Shorewall > Servers
> 
> Shorewall is on its own Linux box, router.  Yes, this is my gateway.
> Spiceworks is on one of the servers sitting behind the router.

OK, 2 things come to mind :
1) When packet tracing, the packets still appear even if they are firewalled. 
Ie, at the bottom layer the packets still show even though they get dropped 
later in the network filter stack. This is only an issue when looking at 
traffic on the firewall itself.

2) Just what is the IDS picking up ? Even if the firewall drops all traffic to 
an IP, you may well still see connection attempts from the internal servers - 
these won't get answered, but you'll still see the initial TCP-Syn packets. IN 
fact, you may see more of them as connection attempts get retried after 
timeouts.

So look first at what the IDS is actually detecting. If it's only TCP-Syn 
packets (ie a connection attempt) then that may be normal. Only if you get 
replies is there much to worry about.

Now, that does change a little depending on the nature of the malware. For some 
sites, the fact that there is a connection attempt may be an indication that 
you have a system carrying a lurgy. For many, it'll be no more than a link 
buried in legitimate sites causing connection attempts.



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