[isapros] Re: Port Scan
- From: "Jim Harrison" <Jim@xxxxxxxxxxxx>
- To: <isapros@xxxxxxxxxxxxx>
- Date: Tue, 25 Jul 2006 13:42:56 -0700
Yep - total agreement and this was the core of the "fight" way back when.
Not only that, but any automated "rule builder" can be used a great DoS
mechanism.
-------------------------------------------------------
Jim Harrison
MCP(NT4, W2K), A+, Network+, PCG
http://isaserver.org/Jim_Harrison/
http://isatools.org
Read the help / books / articles!
-------------------------------------------------------
-----Original Message-----
From: isapros-bounce@xxxxxxxxxxxxx [mailto:isapros-bounce@xxxxxxxxxxxxx] On
Behalf Of Thor (Hammer of God)
Sent: Tuesday, July 25, 2006 12:52
To: isapros@xxxxxxxxxxxxx
Subject: [isapros] Re: Port Scan
.02:
It seems like a total waste of time to respond to "scan attacks" with a block
script, as everything is being blocked anyway- just not with an explicit
"block" rule. The presence of the "scan" alert tells you that ISA is doing its
job - AFAIAC, no other action is even necessary. If there is some incessant
attack from a persistent IP hammering away at published services and you just
don't want to see it, then put in a deny rule. If it is a bandwidth issue
(like when I was getting Code Red attacks all day, every day) then block it on
the ISP side. But that costs money for that service, typically. However, it
does work.
If it is in the realm of "identified" attacks ala my "strikeback" model, then
that is a different thing- and something that is deployed in a completely
different way to solve a different problem (lest someone tried to use that
against me ;). Port scans and "noise" traffic an safely be ignored.
t
On 7/25/06 11:58 AM, "Jim Harrison" <Jim@xxxxxxxxxxxx> spoketh to all:
> Think way back to your involvement with SBS in the Yahoo list.
> It was how I got invited to join that list; the BlockAttacker script
> was being touted as the be-all, end-all to ISA port scan response.
> I had to get really nasty (even for me) with the proponent of this
> technique before he finally backed down.
> He still regurgitates this nonsense (among other senseless
> meanderings) from time to time, but it's an easy head-slap.
>
> For those not familiar, the BlockAttacker script was an expansion of
> the ISA 2000 alert action example that used the client IP to create a
> packet filter blocking the "offending host". While it provided an
> excellent example of using ISA alert environment variables, it turned
> out to be a great DoS tool as well and we pulled it from isatools.org.
>
> Unfortunately, there is one (TSu) individual who shall remain nameless
> (Tony
> Su) who insists on singing the praises of this response technique to
> unsuspecting ISA admins. Luckily, he's not skilled enough to sort out
> how to port the script to ISA 2004 or we'd have more PSS calls than we do now.
>
> -------------------------------------------------------
> Jim Harrison
> MCP(NT4, W2K), A+, Network+, PCG
> http://isaserver.org/Jim_Harrison/
> http://isatools.org
> Read the help / books / articles!
> -------------------------------------------------------
>
>
> -----Original Message-----
> From: isapros-bounce@xxxxxxxxxxxxx
> [mailto:isapros-bounce@xxxxxxxxxxxxx] On Behalf Of Amy Babinchak
> Sent: Tuesday, July 25, 2006 11:21
> To: isapros@xxxxxxxxxxxxx
> Subject: [isapros] Re: Port Scan
>
> I don't know that joke. I think it was before my time on the list.
> What's the block attacker script? Never heard of it.
>
> Amy Babinchak
>
>
>
>
>
>
> -----Original Message-----
> From: isapros-bounce@xxxxxxxxxxxxx
> [mailto:isapros-bounce@xxxxxxxxxxxxx]
> On Behalf Of Jim Harrison
> Sent: Tuesday, July 25, 2006 2:19 PM
> To: isapros@xxxxxxxxxxxxx
> Subject: [isapros] Re: Port Scan
>
> Ask Tony for the BlockAttacker script.
> I'm sure he's still trying to support it.
> :-p
>
> Tom has it right; you can generally ignore them, since damn few ISPs
> even care.
>
> -------------------------------------------------------
> Jim Harrison
> MCP(NT4, W2K), A+, Network+, PCG
> http://isaserver.org/Jim_Harrison/
> http://isatools.org
> Read the help / books / articles!
> -------------------------------------------------------
>
>
> -----Original Message-----
> From: isapros-bounce@xxxxxxxxxxxxx
> [mailto:isapros-bounce@xxxxxxxxxxxxx]
> On Behalf Of Amy Babinchak
> Sent: Tuesday, July 25, 2006 10:21
> To: isapros@xxxxxxxxxxxxx
> Subject: [isapros] Port Scan
>
> What should I do about a port scan that just won't go away? I've got
> two IP addresses port scanning my server around the clock. An email to
> the owner bounced back, unknown email address.
>
> Is there anything to be done?
>
>
> Amy
>
>
>
>
> All mail to and from this domain is GFI-scanned.
>
>
>
>
> All mail to and from this domain is GFI-scanned.
>
>
>
>
All mail to and from this domain is GFI-scanned.
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