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

[Bob Overberg]

IPsec protocols ESP and AH are also common examples -- IP protocols 50 and
51

Bob Overberg
R.Overberg at ieee.org



On Thu, Sep 15, 2011 at 5:28 PM, Bryan J Smith <b.j.smith at ieee.org> wrote:

> Thanx, I was hoping I'd find someone who agreed.
>
> There are so many, common solutions aspects of exchange that do not.  Ping
> is a type of ICMP (IP protocol 1).  The type is contained in the header of
> the IP packet (layer 3) itself, and does not use a transport.  There are
> several others involved with PXEBoot'ing, which is very, very important when
> you're trying to netboot systems.  And I can state countless other, "real
> world" examples too.  And that's before I dive into security aspects.
>
> Understand I dove into this because I run into individuals at clients that
> not only think _exactly_ like this, but that one individual will undermine
> my trying to help the rest of their team.  It's one thing to get the dumb
> stare like many do when we walk into Radio Shack, that's understandable as I
> don't expect everyone to know everything, but only where their experience
> has been.  But it's not about not following, it's about _undermining_ the
> knowledge some someone is trying to share it, and help you.
>
> I've been involved with everything from IEEE subcomittees to government
> installations to 5 figures of nodes in computing and trading grids.  There
> is nothing more destructive than people talking where they don't have
> experience, and stating incorrect information.  It starts with
> over-simplification, but that's usually not bad.  Most people do web, maybe
> remote shells, and you're talking TCP segments passing back and forth
> between source and destination ports.  But I saw where it was going, and my
> assumptions proved right.  They quickly became factually incorrect.
>
> You don't have to be doing real-time, Infiniband and other exchanges to not
> have transports using ports.  There are many, common IP protocols and
> framing exchange, even some higher-level applications, that do not use
> transports with ports.  As I used as an example above, troubleshooting
> PXEboot is one area where you really need to be familiar with this,
> especially.  But I could dive into many other, real world cases.
>
>
>
>
> ----- Original Message -----
> From: Joel J. <tcepsa at gmail.com>
> Sent: Thursday, September 15, 2011 5:11 PM
>
> GGR> 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
> GGR> 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
> GGR> seen on the network, but it is still present.
>
> I'm going to have to go with Brian on this one.  For example, I
> present the humble ping application.  It communicates with another
> computer across a network, yet does not use a port.
>
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