Re: help for port scanning on firewalls and routers

[Matt <matt () use net>]

On Tue, 16 Apr 2002, Gerald Combs wrote:

> On Tue, 16 Apr 2002, Joseph Taylor wrote:
>
> > I am planning to perform port scanning for routers and
> > firewalls security on my network.
> > My questions are about what benefits I will obtain by
> > running a port scanning tool (NMAP, ISS, etc..).
> >
> > Will there be any difference in the results whether I
> > use this tool inside my network (from an internal IP)
> > or outside my network.
>
> > What's the aim of running this tool from internal
> > network?
>
> Two main benefits are inventory and security analysis.  After running an
> Nmap scan, people often find services (and entire machines) on their
> network that they weren't aware of.  Internal scans can help you secure
> your network from internal breakins (by employees) and from external
> breakins (in case someone makes it through your firewall).


I'm not an IT/operations person, but I've used nmap for basic validation
of state table handling code in firewall/NAT/IDS/VPN applications and
devices. Doing some SYN/NULL/ACK/FIN scans through a firewall/NAT/VPN
device, both fragmented and non-fragmented can sometimes cause things like
a linksys NAT device to choke and die.

Another good tool for this kind of testing is isic, which I believe is
hsoted on packetfactory.net currently.

Sorry if this doesn't help you, I haven't really played much in this space
for a couple years. If you want to look at my old slides for hte testing
talk I did a few years ago, they're @
http://www.clock.org/~matt/thinks.html .

I'm currently working for a company that makes a "security QA" tool
(Cenzic, fka ClickToSecure), but it's a bit expensive and nmap + isic will validate what most people care
about.

Hope this helps!


--
http://www.clock.org/~matt


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