Re: design of nmap

["Eddie Bell" <ejlbell () gmail com>]

Hi Kaushik,

The scanning engine works by using a state machine. In simple terms, a
big switch statement with supporting data structures that store the
state.

When a packet is received the data structures are checked using the
packets source address. If we find a match then the packet is from a
host we are scanning. We then try and match the packet to a specific
port and record the results in the data structure.

The sending and receiving of packets is interleaved based on various
timing constraints and what packets are available.

This is a very simplistic view of what actually happens but for more
detail check out scan_engine.cc. There is also a less complex but
similar algorithm in traceroute.cc

thanks
 - eddie

On 04/05/07, Kaushik Das <kaushikdas24x7 () yahoo co in> wrote:
> Hi,
>     Can someone throw some light on the software design of nmap in general.
>
>     Specifically, my question is -
>       nmap is a single threaded application. How does it transmit and receive packets   simultaneously?
>
>    Thanks in advance,
>    - Kaushik.
>
>
>
>
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