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Re: i've been port scanned. now what



On Mon, Mar 05, 2001 at 11:37:17PM +0100, Szabó Dániel wrote:
> Hello.
> My packet filter ruleset catched somebody on port scanning one of our host.
> He or she tryed to scan a very big port range from tcp 1 up to 32000 (think
> with nmap), but my packet filter denied his/her queries (the kernel
> generated 1 mb log in 3 minutes with the denied packets). I have his/her
> ipv4 address, and i would like to ask, what should i do know? i figured out
> from the ripe.net whois db, that the ip is owned by one of the ISP's from my
> country, is it possible, that the scanner cracked the isp's machine, then
> pushed the scan from there?

Well, that all depends ... do you consider port scanning criminal
activity or not?

I do not - I think you should view a port scan as a possible
indication that someone intends to attack you.  It's also possible
that someone is just exploring.

As a former network administrator I wasn't too worried about portscans
unless they were followed up with actual connections.  I also used
portscans when needed to discover what users on the network were up
to.

You could always send an email to the ISP in question and ask them
what they think; whether they want a copy of the logs, etc.

-- 
Nathan Norman - Staff Engineer | A good plan today is better
Micromuse Inc.                 | than a perfect plan tomorrow.
mailto:nnorman@micromuse.com   |   -- Patton

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