Re: TELNET instead PING

From: Gandalf (gandalf_at_geochemsource.com)
Date: 01/26/04 

Date: Mon, 26 Jan 2004 21:31:41 +0100
To: "comp.lang.python" <python-list@python.org>

Peter Hansen wrote:

>DCK wrote:
>
>
>>Into group-archive i found most e-mails, which touches PINGing.
>>In my work i've used TELNET for testing if host is operational.
>>Sometimes, for unknown reasons, workstation doesn't respond
>>for PINGing. But in WinNT network, all hosts has a nbsession
>>listening on port 139. I always use this script instead PING
>>command (hope, will be usefull for someone :) ):
>>
>>
>
>Interesting, but why would you use TELNET for that? Telnet is
>simply one of many possible protocols, whereas you need only
>open a socket to the port to see if the host is responding.
>
>
Exactly. All you need is an open port you can check.

Note: that reason you talked about is most likely a packet filtering
firewall. A good firewall
can block PING, Telnet, Nbsession and many others. In most cases, the
best policy
is to lock everything by default and permit only the ones you really
want. Firewall
rules can include source addresses too. It is possible that a computer
do not respond
on PING and TELNET ports for you but it does for a similar request from
another
computer. I think there is no universal way to determine if a remote
host is alive or not.

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