[CALUG] DoD/OSI Layer 2, 3 and 4 in the real world -- WAS: open ports

[Rajiv Gunja]

Sorry Bryan. I cannot accept your answer.

GGR> So, irrespective of the application, everything communicating
GGR> over the network has a port address.

BJS> This is _false_.  Not trying to be anal here, but understand my initial
response was hoping to avoid the mega-oversimplification that I'm BJS>
seeing too often.  I was afraid it would go here.

Yes, every application that talks over the network or within the OS itself
has a port, it may be a temporary port, but it is present. In fact when 1
app talks to another app within the same server/pc, a port is opened for
communication. It may not be seen on the network, but it is still present.

About using tcpdump/snoop(solaris) over netstat. True netstat gives network
information, it is a good step to get on to learn about network traffic. But
for running it on a PC, it does not matter (since we are all behind a router
at home).

Also, to learn something, we need to simply stuff first, else we will drive
away folks who want to learn. If we make things sound like brain surgery,
then no one will want to learn about subjects.


--
Rajiv G Gunja
Blog: http://ossrocks.blogspot.com


On Thu, Sep 15, 2011 at 16:22, Bryan J Smith <b.j.smith at ieee.org> wrote:

> > So, irrespective of the application, everything communicating
> > over the network has a port address.
>
> This is _false_.  Not trying to be anal here, but understand my initial
> response was hoping to avoid the mega-oversimplification that I'm seeing too
> often.  I was afraid it would go here.
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