Firewall Wizards: Re: source port specific port scan

[m p <sumirati () yahoo de>]

 --- Rich Wilson <wk633 () yahoo com> schrieb: 

> Does anyone know of a port scanner that allows you to specify the source
> port? 
> I'm trying to test a filter that allows outbound only SMTP.  My worry is that
> it is not stateful, and that an attacker using a source port of 25 can bypass
> the filter.
Hi Rich,

try nmap with parameter -g <source port>. Excerpt from the man page:
   
 -g <portnumber>
         Sets the source port number used  in  scans.   Many
         naive firewall and packet filter installations make
         an exception in their ruleset to allow DNS (53)  or
         FTP-DATA (20) packets to come through and establish
         a connection. 


Information about nmap can be found under:
http://www.insecure.org/nmap 

I hope that helps

Marc

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