[ale] Nmap host up/down status

[Chris Fowler]

Nmap is not providing an exit code on failure. The doc confirm this. I'll just need to capture the output and parse that. No problem. 

[root at test]# time nmap -sn -PE -PP -PM -PO -n 10.139.128.170 2>&1 >/dev/null; echo $? 
real 0m 3.05s 
user 0m 0.01s 
sys 0m 0.02s 
0 
[root at test]# time nmap -sn -PE -PP -PM -PO -n 127.0.0.1 2>&1 >/dev/null; echo $? 
real 0m 0.02s 
user 0m 0.00s 
sys 0m 0.01s 
0 

Chris 

----- Original Message -----

> From: "dev null zero two" <dev.null.02 at gmail.com>
> To: "Atlanta Linux Enthusiasts" <ale at ale.org>
> Sent: Friday, October 10, 2014 4:04:47 PM
> Subject: Re: [ale] Nmap host up/down status

> "nmap -sn host"

> if that is unreliable, you could try "nmap -sn -PE -PP -PM -PO host"

> if you know certain ports that will be open, you could use -PS80 for a SYN
> ping to port 80 or -PU13337 for a UDP ping to port 13337 (you want to use a
> closed port).

> On Fri, Oct 10, 2014 at 3:53 PM, Chris Fowler < cfowler at outpostsentinel.com >
> wrote:

> > I have a script I use in Perl that tests a list of hosts via the exit code
> > of
> > ping. Some hosts, like Winders, will ignore ICMP ECHO and this creates
> 
> > false alerts.
> 

> > The idea popped in my head today to use the exit code of nmap and allow it
> > to
> > test for me.
> 

> > Can someone clue me in on the best command like options to nmap that will
> > allow it to make a decent determination of a host is up?
> 

> > I did think about running an initial port scan and then doing an accept()
> > test on a TCP socket, but then I decided maybe I'd just let nmap make
> 
> > the up/down decision.
> 

> > Chris
> 

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