# Nmap OS detection issue



## rbelk (Apr 8, 2009)

OK Guy's I've got a good one. Nmap OS Dection on FreeBSD is extremely slow!!

When I "nmap -O" a host on my Linux workstation I get this response
*Nmap done: 1 IP address (1 host up) scanned in 12.085 seconds*.

When I "nmap -O" the same host on my FreeBSD machine I get this response.
*Nmap done: 1 IP address (1 host up) scanned in 322.02 seconds*

I would have thought FreeBSD would have been quicker?! Is there some command switch I need to add to increase the speed of OS Detection?


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## SeanC (Apr 8, 2009)

Using the switch *--osscan-limit* instead of *-O* is quicker. But, I've never gotten the same time twice. Even doing the same scan back-to-back can give wildly different results.

There are many options you can try:
http://www.freebsd.org/cgi/man.cgi?query=nmap&sektion=1&manpath=FreeBSD+7.1-RELEASE+and+Ports


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## SirDice (Apr 10, 2009)

Turn off your firewall, it may interfere with the scanning.


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## rbelk (Apr 10, 2009)

SirDice, the script I run automatically turns off the firewall. I have also fixed the time iss. Here is what I am using now.

*nmap -A -T5 <ip address>*

Takes just a few seconds more than Linux.

Quick question also. How can I rename my post to add [SOLVED] in the Thread Subject?


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## DutchDaemon (Apr 10, 2009)

rbelk said:
			
		

> Quick question also. How can I rename my post to add [SOLVED] in the Thread Subject?



Do you have a 'Thread Tools' pulldown menu at the top right of your first post of this thread? You should be able to Edit Thread and select Solved from a menu.


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## rbelk (Apr 10, 2009)

DutchDaemon, I do have the thread tools but that option is not in the dropdown. I have edit rights to my posts but I can not edit the Thread title.


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## DutchDaemon (Apr 10, 2009)

Ok, I have no idea what the cut-off point is where you can use that option. Maybe you have to be a 'Member' instead of a 'Junior Member'. I have no insight in how that part of the boards works. I have added the [Solved] tag.


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## rbelk (Apr 10, 2009)

I did have access to that option and I added [solved] to this thread that I started, http://forums.freebsd.org/showthread.php?t=2382


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## SeanC (Apr 13, 2009)

Frankly, nothing needed to be solved because there was never a problem. 

Sorry, I'm just being cranky.


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## Djn (Apr 13, 2009)

SeanC said:
			
		

> Frankly, nothing needed to be solved because there was never a problem.
> 
> Sorry, I'm just being cranky.



Problem: "I try to do OS detection with the same switches I used on linux. It takes forever."
Solution: "Using these extra switches gives the expected results."

It's all in how you look at it. :e


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## SeanC (Apr 13, 2009)

Djn: You are right, of course. I probably should not visit the Forums when I am half-caffeinated _and_ after a holiday weekend with the family.


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