Re: verifying an open or closed port on an ip address

[James Fields <jvfields () tds net>]

Sorry, I lost the original posting - netcat is a great tool for what you
want.  It's kind of like using telnet to connect to a port, but it works
for both UDP and TCP ports and you can pipe commands through it. 
Versions are available for both Windows and Unix.  You can find it at
the www.atstake.com web site - poke around there for free utilities...

On Sat, 2003-08-09 at 13:30, Birl wrote:
> As it was written on Aug 7, thus ian () kingcon com spake unto security-basics...:
>
> Ian:  Date: Thu, 7 Aug 2003 13:44:58 -0400
> Ian:  From:  <ian () kingcon com>
> Ian:  To: security-basics () securityfocus com
> Ian:  Subject: verifying an open or closed port on an ip address
> Ian:
> Ian:  Hello,
> Ian:
> Ian:  I am looking for a windows compatible utility or method, preferably
> Ian:  command line, where I can verify whether a port on an ip address is
> Ian:  reachable or not.  I want to be able to do individual ports and not
> Ian:  port scans.  Say for instance I wish to verify that port 677 is
> Ian:  closed to traffic on ip address Ex. 172.16.0.1, I'm looking for a
> Ian:  utility that would do something like:
> Ian:
> Ian:  Check 172.16.0.1 port 677
> Ian:
> Ian:  and tell me whether that port was reachable.
> Ian:
> Ian:  So if I have two networks and I use this command from one I can
> Ian:  determine whether a port is reachable on another.  To determine
> Ian:  whether a security measure is failing or not.
> Ian:
> Ian:  There may be a simple way to do this...
> Ian:
> Ian:  Thanks
> Ian:  Ian
>
>
>
> I dont understand why you wouldnt portscan.
>
> You could tell nmap (or in your OS, WinNmap) to just probe a single IP's
> UDP (or TCP) port.
>
> nmap is designed to be flexable.  It's what I use when testing for a
> specific port.
>
>
> Thanks
>
>  Scott Birl                              http://concept.temple.edu/sysadmin/
>  Senior Systems Administrator            Computer Services   Temple University
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>
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-- 
James V. Fields


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