script or other suggestion

[Herta Van den Eynde]

On 23/11/2007, Broekman, Maarten <Maarten.Broekman at fmr.com> wrote:
> Why not just do DNS lookups to see which ones are assigned?
>
> To build on what Cameron mentioned, just put in "host $i" in the loop
> and check to see it returns anything sane.  If so, you might want to
> ping it to see if it's up, but as Cameron said, the system could be down
> or off so that's not 100% reliable.
>
> Maarten Broekman
> Email: maarten.broekman at fmr.com
>
> -----Original Message-----
> From: redhat-list-bounces at redhat.com
> [mailto:redhat-list-bounces at redhat.com] On Behalf Of Cameron Simpson
> Sent: Thursday, November 22, 2007 4:10 PM
> To: General Red Hat Linux discussion list
> Subject: Re: script or other suggestion
>
> On 22Nov2007 15:35, chloe K <chloekcy2000 at yahoo.ca> wrote:
> | I have ip list in my network
> | I need to check which ip is unused
> | what is better solution?
> |
> | Write the ping script or use other command
> |
> | eg:
> |
> | for i in ip.txt
> | ping -c 3 $i
>
> That would be:
>
>   for i in `cat ip.txt`
>   do  ping -c 3 $i || { echo "IP $i is not in use."; break; }
>   done
>
> Of course, if a machine happens to be down/off, if will look
> like its IP is not in use...
>
> You could possibly do something clever with nmap or "ping -b",
> but your approach is simple and effective.
> --
> Cameron Simpson <cs at zip.com.au> DoD#743
> http://www.cskk.ezoshosting.com/cs/

To make matters worse, a system may be up but firewalls may block pings.

Kind regards,

Herta