Detecting computers on network

[Sandeep Arya]

Thanks linuxfreak and sybren for positive comments

My application will be running on Linux.
How to send ICMP ECHO as broadcast packets. I do not know this. Please tell
me how to?

Sybren.. Does nmap is available on every systems? I tried on my linux fc4
machine in user previleage. it was not working. Does this just belongs to
superuser...

Is there any other way ? Can just socket.connect or sendto help me? I.E.
their return valuess...

Sandeep


From: Sybren Stuvel <[email protected]>
To: (e-mail address removed)
Subject: Re: Detecting computers on network
Sent: Friday, July 22, 2005 1:59 AM

linuxfreak enlightened us with:

How about sending an ICMP echo packet to your broadcast address and
checking which hosts send a reply

Won't work on all boxes. Windows boxes ignore broadcast pings, for
example.

I'd go for a call to "nmap -sP" instead, and filter it's output.

Sybren

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[gene tani]

Hi Sandeep,

i didn't see where you said if these hosts you want to ping are on your
internal network, or beyond your gateway. Probably the only truly
reliable way to maintain an active hosts list is to install a
ping-sending client on them, like

http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/52302

And think about possible legal ramifications of port scanning hosts or
possibly getting your IP blacklisted by a host's firewall, before you
do it.

 

[Cameron Laird]

Hi Sandeep,

i didn't see where you said if these hosts you want to ping are on your
internal network, or beyond your gateway. Probably the only truly
reliable way to maintain an active hosts list is to install a
ping-sending client on them, like

http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/52302

And think about possible legal ramifications of port scanning hosts or
possibly getting your IP blacklisted by a host's firewall, before you
do it.

Let me shift that excellent summary very slightly: it might
help to clarify what "active host" means. In some situations,
managers just want to know, "which of our Web servers respond
to requests for their top-level page?" If you're dealing with
*that* (or which mail servers are serving mail, or ...), then
it's entirely appropriate simply to perform the operation (to
request a page through HTTP, for example) in question.

 

[Marek Kubica]

Hello!

Sybren.. Does nmap is available on every systems? I tried on my linux fc4
machine in user previleage. it was not working. Does this just belongs to
superuser...

I'm not Sybren, but I think I'm able to respond.
nmap is only available if it is installed on the system, on Debian you
would need to install the package nmap first. It is not really a good idea
hoping nmap to be installed.

You can use nmap as a normal user, but some advanced scanning options are
reserved for superuser.

greets,
Marek