Peace all,

Many thanks for your comments...

For those of you bet on the IP stack problem, you win :)
We redid the scan last weekend to make sure of this.

The problem is more of the limitation of the OS/machine being scanned.
From all the AS/400 machines being scanned, only the 730 machine was seriously affected by nmap probes.
It automatically assign a user for the TCP/IP connection and started numerous jobs (which had to be manually ended for them to stop).
The rest of them didn't have this problem -- newer machines and OS-es.

I agree with Jon that networking in this AS/400 is much more like an add-on after thought :)
And it's pure luck in my opinion that no one before this brought the machine down (they have a team which also does ports scanning to their production servers, including this problematic one).
Oh well, at least I learned something new =)

Thanks and Regards,
=adley=

-----Original Message-----
From: Rick Zhong [mailto:sagiko (at) gmail (dot) com [email concealed]]
Sent: Saturday, May 17, 2008 2:50 PM
To: Brahnda A. Eleazar
Cc: pen-test (at) securityfocus (dot) com [email concealed]
Subject: Re: Dangerous in using nmap for AS/400 730 machine configured with 3 ASPs?

I will put my bet on the crash of IP stacks as well. Those systems
just can't handle the nmap probing packats properly. A very common
scenario is the systems open connections and allocate resources, but
fail to close them properly. I encountered these cases not only on
AS400, some old solaris OS also have similar issues.

On Fri, May 16, 2008 at 10:46 AM, Brahnda A. Eleazar
<brahnda.e (at) hermisconsulting (dot) com [email concealed]> wrote:
> Peace all,
>
> I am wondering whether this is related or not.
> I was in the middle of beginning a pentest activity for a network segment containing quite a number of AS400 (Production).
> I started with a simple nmap first to see what I am facing.
> My command was (IPs are masked) "nmap -sV -vv -p 8470-8476 -o firsttry_port.nmap xxx.xxx.xxx.0/24"
> This lasted for about 15 minutes.
>
> After about 2 hours later, 2 out of 50+ identifiable machines started having problems.
> They became very slow.
> Those two machines are using ASP (Auxiliary Storage Pools), 1 ASP on the 1st machine and 2 ASPs on the 2nd.
>
> I just want to get more information whether my nmap did anything "bad"? :)
>
> Thanks and Regards,
> =adley=
>
>
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