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Date:      Sun, 22 Feb 2004 10:08:47 -0500
From:      Marty Landman <MLandman@face2interface.com>
To:        Olaf Hoyer <ohoyer@gaff.hhhr.ision.net>
Cc:        freebsd-questions@freebsd.org
Subject:   Re: DHCP access
Message-ID:  <6.0.0.22.0.20040222095859.03dc3c78@pop.face2interface.com>
In-Reply-To: <20040222153958.S56797@gaff.hhhr.ision.net>
References:  <E1AuKeY-0003wT-Bn@dick.ccstores.com> <20040221052137.GL24309@hardesty.saintaardvarkthecarpeted.com> <6.0.0.22.0.20040221092538.05e6dc48@pop.face2interface.com> <4037D5D7.8030700@mac.com> <6.0.0.22.0.20040222085418.01b94e68@pop.face2interface.com> <20040222153958.S56797@gaff.hhhr.ision.net>

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At 09:42 AM 2/22/2004, Olaf Hoyer wrote:

>The syntax to ping a whole /24 segment would be:

Hi Olaf. Could you please explain what is meant by '/24 segment'? I'm new 
to networking as you can see!

>nmap -sP 192.168.0.0/24

# nmap -sP 192.168.0.0/24

Starting nmap V. 3.00 ( www.insecure.org/nmap/ )
Host   (192.168.0.0) seems to be a subnet broadcast address (returned 2 
extra pings).
Host delliver (192.168.0.1) appears to be up.
Host woody (192.168.0.3) appears to be up.
Host swamisalami (192.168.0.7) appears to be up.
sendto in send_ip_raw: sendto(4, packet, 28, 0, 192.168.0.8, 16) => Can't 
assign requested address
Sleeping 15 seconds then retrying
sendto in send_ip_raw: sendto(4, packet, 28, 0, 192.168.0.8, 16) => Can't 
assign requested address
Sleeping 60 seconds then retrying
sendto in send_ip_raw: sendto(4, packet, 28, 0, 192.168.0.8, 16) => Can't 
assign requested address
Sleeping 240 seconds then retrying
^Ccaught SIGINT signal, cleaning up
swamisalami#

>this will work.

It appears not. I should perhaps add that I'm running this from my fbsd box 
which is not the gateway. Nmap has reported itself (swamisalami), the 
gateway box (delliver) and the debian box (woody). It's not reported the 
rh9 box (penguin) and my wife's w98 workstation (eileen).

>after this you will also have some output from the arp -a command,
>because the arp cache has to be filled somehow.

swamisalami# arp -a
? (192.168.0.0) at ff:ff:ff:ff:ff:ff on ep0 permanent [ethernet]
delliver (192.168.0.1) at 00:08:74:c0:5e:69 on ep0 [ethernet]
woody (192.168.0.3) at 00:a0:cc:40:3e:9b on ep0 [ethernet]
swamisalami (192.168.0.7) at 00:20:af:4d:24:b7 on ep0 permanent [ethernet]
? (192.168.0.8) at (incomplete) on ep0 [ethernet]
penguin (192.168.0.160) at 00:a0:24:75:04:49 on ep0 [ethernet]
eileen (192.168.0.240) at 00:a0:cc:40:55:cf on ep0 [ethernet]
? (192.168.0.255) at ff:ff:ff:ff:ff:ff on ep0 permanent [ethernet]
swamisalami#

Ok, not sure why the output was broken up into two portions but it has now 
captured all the nodes on my box. Furthermore a subsequent arp -a gives a 
more usable output e.g.

swamisalami# arp -a
? (192.168.0.0) at ff:ff:ff:ff:ff:ff on ep0 permanent [ethernet]
delliver (192.168.0.1) at 00:08:74:c0:5e:69 on ep0 [ethernet]
woody (192.168.0.3) at 00:a0:cc:40:3e:9b on ep0 [ethernet]
swamisalami (192.168.0.7) at 00:20:af:4d:24:b7 on ep0 permanent [ethernet]
penguin (192.168.0.160) at 00:a0:24:75:04:49 on ep0 [ethernet]
eileen (192.168.0.240) at 00:a0:cc:40:55:cf on ep0 [ethernet]
? (192.168.0.255) at ff:ff:ff:ff:ff:ff on ep0 permanent [ethernet]
swamisalami#



Did you mean then that I should run the nmap followed by the arp -a to get 
a look at all nodes on my class c network? In this case it seems the only 
thing needed for me to put this into a shell script is a way to not have to 
manually interrupt the nmap which seemed to want to keep trying, after 
sleeping for progressively longer periods of time. Unless there is a glitch 
to be worked around somehow on 192.168.0.8 (never in use on my network 
afaik) and that what happened here was not typical behavior.

It would be a nice utility for me to have and perhaps run off cron - i.e. 
to test each connection on my network and report back so I know on a steady 
basis that everything's up and running (or at least reachable).


Marty Landman   Face 2 Interface Inc 845-679-9387
This Month's New Quiz --- Past Superbowl Winners
Make a Website: http://face2interface.com/Home/Demo.shtml



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