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Re: Suspect that --host-timeout is not working in 4.50?
From: jah <jah () zadkiel plus com>
Date: Fri, 14 Dec 2007 22:42:21 +0000

On 14/12/2007 20:52, Randolph Reitz wrote:
Hi,

I have installed nmap 4.50 on the scanner farm here at Fermilab and  
I've noticed that some nmap scans are running a long time.  For  
example ...

scanner   5311 31009  0 12:17 ?        00:00:00 /bin/bash ./bin/ 
run_nmap.sh --pro -d 1 -sS -p 1-65535 -A 131.225.232.A 131.225.232.B  
131.225.232.C 131.225.232.D
root      5319  5311  2 12:17 ?        00:03:10 /usr/local/bin/nmap - 
sS -p 1-65535 -P0 -T4 --osscan-limit --osscan-guess --host-timeout 15m  
-A -oX - 131.225.232.D

It's now
date
Fri Dec 14 14:47:47 CST 2007

The nmap started at 12:17 and has collected 3 minutes of CPU so far.   
The host_timeout is set for 15 minutes.  So far, I've collected  
hundreds of examples of long-running nmap scans.  However, I've  
noticed that nmap 4.50 is much faster than 4.2.

Does anyone else have a problem with --host-timeout?
Hello Randolph,

I don't seem to be having any problems with --host-timeout, may I 
propose a quick test...

Perform a simple test scan against a couple of hosts with the aim of 
finding a host/scan combination that takes at least 2 seconds, but as 
short as possible (this is supposed to be a quick test).  An example 
might be:

    nmap -d -sU -p1-5000 <target>


When you have a total scan time that suits, add the lowest permissible 
host-timeout (1501ms):

    nmap -d -sU -p1-5000 --host-timeout 1501 <target>


if host-timeout is working properly, you should see something like:

    ...
    Completed ARP Ping Scan at 22:35, 0.05s elapsed (1 total hosts)
    ...
    <target> timed out during UDP Scan (0 hosts left)
    Completed UDP Scan at 22:35, 1.46s elapsed (1 host timed out)
    Host <target> appears to be up ... good.
    Skipping host <target> due to host timeout
    ...

If that's a success, you could start building up the scan paramaters 
again and hopefully determine what's gone wrong.

Hope that helps a bit,

jah

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