Chad Waters on 29 Jun 2009 18:32:01 -0700

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Re: [PLUG] Find Open Ports

On Mon, Jun 29, 2009 at 9:07 PM, Casey Bralla<X> wrote:
> My employer is very aggressive in closing off ports.  This makes it hard for me
> to access my home network from work.  Luckily, port 23 is open so I can ssh
> in, and of course, port 80 is left alone.
> However, I've got several special web pages that run on computers behind my
> firewall.  I access them through port forwarding to non-standard ports (such as
> 81 & 82).
> Unfortunately, since my employer blocks these ports, I can't use them.   I do
> have unlimited discretion, however, in assigning my programs to whatever port
> I desire.
> So....  if I knew which ports were NOT blocked, I could use those.
> BUT...  How do I check to see if what ports are available?
> So far, I've been able to come up with 2 ideas:  1) scan every port, and 2)
> try ports manually one at a time.
> I could run a portscan on my portable, but that would undoubtedly raise all
> kinds of alarms.  Also, I'd have to be sure I was connecting to something that
> had those ports active.
> Does anybody have any suggestions on how to test to see if a series of ports
> is not filtered, or have a suggestion of ports that I could test manually
> through trial and error?

1) ssh typically listens on tcp 22. telnet is tcp 23.

2)If you did that on my network, I probably would have your switchport
admined down before you finished your scan.
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