Re: How to detect whether firewall service is provided by server or by ISP?

[Paul Johnston <paul.johnston () pentest co uk>]

Hi,

If some ports are allowed through the firewall you have a chance. I've
never done this, but in theory it will work in some circumstances:

Say port 80 is allowed. First, use tcptraceroute on that port to
discover the path distance (number of hops) to the target. Now pick a
port that isn't allowed. Again, use tcptraceroute to determine find the
last hop that gets a "ttl exceeded" reponse, before you get no responses
(because of the firewall).

If this is one less than the path distance, you can say with reasonable
certainty that it's a host firewall. Otherwise, this would imply a
router/front-end firewall.

Paul




On 16/09/2010 12:23, martin wrote:
> I have two servers behind different networks. First network is
> protected with firewall provided by the router and there is no
> firewall in the server:
>
> [root@martin ~]# nmap --reason -n -PN -p445 192.168.217.73
>
> Starting Nmap 5.00 ( http://nmap.org ) at 2010-09-16 13:57 EEST
> Interesting ports on 192.168.217.73:
> PORT    STATE    SERVICE      REASON
> 445/tcp filtered microsoft-ds no-response
>
> Nmap done: 1 IP address (1 host up) scanned in 2.15 seconds
> [root@martint ~]#
>
> The other server is in the second network and there is no firewall
> service provided by the router, but firewall is activated in the
> server:
>
> [root@martin ~]# nmap --reason -n -PN -p9731 192.168.13.19
>
> Starting Nmap 5.00 ( http://nmap.org ) at 2010-09-16 13:56 EEST
> Interesting ports on 192.168.13.19:
> PORT     STATE    SERVICE REASON
> 9731/tcp filtered unknown no-response
>
> Nmap done: 1 IP address (1 host up) scanned in 2.15 seconds
> [root@martin ~]#
>
> Is there somehow possibility to detect, whether firewall is active in
> the server or in the router?
>
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------------------------------------------------------------------------
Securing Apache Web Server with thawte Digital Certificate
In this guide we examine the importance of Apache-SSL and who needs an SSL certificate.  We look at how SSL works, how 
it benefits your company and how your customers can tell if a site is secure. You will find out how to test, purchase, 
install and use a thawte Digital Certificate on your Apache web server. Throughout, best practices for set-up are 
highlighted to help you ensure efficient ongoing management of your encryption keys and digital certificates.

http://www.dinclinx.com/Redirect.aspx?36;4175;25;1371;0;5;946;e13b6be442f727d1
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