Detecting computers on network

[Sandeep Arya]

Hello dear

I had sent my earlier queries regarding same topic. However just to be more
specific this time..

I just wann try to detect that if there are some ip address in a list of
some ip address alive or not.

How can i do this?

Shall i try to connect them and check that my connection is working or not?
If working than means alive .... (connection based)

SHalle i send some buffer value (whatever) to socket using sendto(...) and
then checking for return value? (Connectionless )

Well for me it doesnot matter that i should have connection or
connectionless. . I just wannn know who are alive in my LAN?

This application will be for my computers in lan. not for maganetwork.

LAN will have just some bridges and computers.

i need to detect tham all..

however i doesnot matter that all of them replies or not. I just wann know
that atleast some of them reply. Rest i will take care of...


Sandeep

_______________ _______________ _______________ _______________ _____
NRIs, does your family in India need money urgently?
http://creative.mediaturf.net/creati...CI_NRI_ERA.htm Open an
ICICI Bank NRI savings A/c

[linuxfreak]

Re: Detecting computers on network

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

[linuxfreak]

Re: Detecting computers on network

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

[Sybren Stuvel]

Re: Detecting computers on network

linuxfreak enlightened us with:[color=blue]
> How about sending an ICMP echo packet to your broadcast address and
> checking which hosts send a reply[/color]

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
--
The problem with the world is stupidity. Not saying there should be a
capital punishment for stupidity, but why don't we just take the
safety labels off of everything and let the problem solve itself?
Frank Zappa

[Peter Tillotson]

Re: Detecting computers on network

You could use a sniffer in promiscuous mode. pypcap -- or something
like. This will record every packet seen by your network card. Whether
is will work depends on whether you are on a true braodcast network.

if a box is on and completely inactive you'll never see it, but most
boxes do something. Windows boxes positively shout about there presence :-)

baically this is pasive nmap, nmap will try to open a tcp or udp
connection on every machine. your going to generat a lot of traffic.

If you've got access to the boxes enabling ICMP and using that is the
proper way.

Sandeep Arya wrote:[color=blue]
> Hello dear
>
> I had sent my earlier queries regarding same topic. However just to be
> more specific this time..
>
> I just wann try to detect that if there are some ip address in a list of
> some ip address alive or not.
>
> How can i do this?
>
> Shall i try to connect them and check that my connection is working or
> not? If working than means alive .... (connection based)
>
> SHalle i send some buffer value (whatever) to socket using sendto(...)
> and then checking for return value? (Connectionless )
>
> Well for me it doesnot matter that i should have connection or
> connectionless. . I just wannn know who are alive in my LAN?
>
> This application will be for my computers in lan. not for maganetwork.
>
> LAN will have just some bridges and computers.
>
> i need to detect tham all..
>
> however i doesnot matter that all of them replies or not. I just wann
> know that atleast some of them reply. Rest i will take care of...
>
>
> Sandeep
>
> _______________ _______________ _______________ _______________ _____
> NRIs, does your family in India need money urgently?
> http://creative.mediaturf.net/creati...CI_NRI_ERA.htm Open
> an ICICI Bank NRI savings A/c
>[/color]

[Sybren Stuvel]

Re: Detecting computers on network

Peter Tillotson enlightened us with:[color=blue]
> You could use a sniffer in promiscuous mode. pypcap -- or something
> like. This will record every packet seen by your network card.
> Whether is will work depends on whether you are on a true braodcast
> network.[/color]

That's not going to work on a switched network, which most modern
networks are.
[color=blue]
> Windows boxes positively shout about there presence :-)[/color]

Definitely true.
[color=blue]
> baically this is pasive nmap, nmap will try to open a tcp or udp
> connection on every machine. your going to generat a lot of
> traffic.[/color]

Not if you tell it to use ICMP pings only.

Sybren
--
The problem with the world is stupidity. Not saying there should be a
capital punishment for stupidity, but why don't we just take the
safety labels off of everything and let the problem solve itself?
Frank Zappa