Re: a basic nmap usage question

[David Fifield <david () bamsoftware com>]

On Mon, Apr 05, 2010 at 09:26:01PM +0000, suiqiangd () gmail com wrote:
> I have a basic nmap usage question. not sure if this is the right place 
> to ask. Please let me know if anyone know a better place for this.
>
> I am using nmap as a TCP SYN packet generator to test out my firewall. It 
> works well so far. However, one thing that I don't know how to control is 
> that it generates 2 SYN for each destination port when SYN is not 
> replied, ie when the first SYN is filtered, nmap sends another SYN to try 
> again. The command I use is:
>
> nmap -sS -PN -r -p500-504 32.1.1.6
>
> How can I disable this retry and tell nmap to only send 1 SYN packet for  
> each destination port? I looked through the man page but didn't find such 
> knob.

Use --max-retries 0. http://nmap.org/book/man-performance.html.

This is the right place to ask questions like this.

David Fifield
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