Compression TCP/IP

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Where in the TCP/IP protocol stack does compression occur?


Regards,

Ben

[bare with me... there is a link to security]




Re: Compression TCP/IP
bensmyth wrote:

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http://userpages.umbc.edu/~jack/ifsm498/tcpip-intro.html

Excerpt:-


        OSI Protocol Stack

    7. Application   -- End user services such as email.
    6. Presentation  -- Data problems and data compression
    5. Session       -- Authenication and authorization
    4. Transport     -- Gaurentee end-to-end delivery of packets
    3. Network       -- Packet routing
    2. Data Link     -- Transmit and receive packets
    1. Physical      -- The cable or physical connection itself.

             TCP/IP Protocol Stack.

    5. Application   -- Authenication, compression, and end user services.
    4. Transport     -- Handles the flow of data between systems and
                        provides access to the network for applications via
                        the (BSD socket library)
    3. Network       -- Packet  routing
    2. Link          -- Kernel OS/device driver interface to the network
                        interface on the computer.



 > [bare with me... there is a link to security]

Quite happy to bear with you but you do not want to see me with my
clothes off ;-)


Re: Compression TCP/IP
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That would assume the end-user applications were aware of data compression. What
if this wasn't the case? Would compression not occur?

On aside, I believe there is an error..... `Network,' should read `internet,'
not to be confused with Internet.


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;-) Will watch my typing in future.....




Re: Compression TCP/IP
Mike wrote:
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When you talk about TCP/IP stack you normally are not talking
about the Application level. Just the Transport level. That's
why I say there's no compression in the TCP/IP stack, because
the Application level don't use to be considered part of the
TCP/IP stack.

Regards.

--

Jose Maria Lopez Hernandez
Director Tecnico de bgSEC
jkerouac@bgsec.com
bgSEC Seguridad y Consultoria de Sistemas Informaticos
http://www.bgsec.com
ESPAŅA

The only people for me are the mad ones -- the ones who are mad to live,
mad to talk, mad to be saved, desirous of everything at the same time,
the ones who never yawn or say a commonplace thing, but burn, burn, burn
like fabulous yellow Roman candles.
                 -- Jack Kerouac, "On the Road"


Re: Compression TCP/IP
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With a dial-up connection (and certain others), the link layer is PPP:
   (ftp://ftp.rfc-editor.org/in-notes/std/std51.txt ).
PPP includes a limited form of compression.

Why is this of interest, anyhow?


Re: Compression TCP/IP
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I'm currently examining IPsec.

If encryption is used, then compression is not possible.

I'm also interested in any potential performance gains (smaller packets ->
faster [IPsec] encryption... but at what overhead? Smaller packers should also
improve performance elsewhere)


Regards,

Ben




Re: Compression TCP/IP
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You compress the data before you encrypt it.

  compress                    decompress
      encrypt               decrypt
          send()  ----->  recv()



Re: Compression TCP/IP
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Sorry, I thought I had already implied that in my last post.

Yes, it is possible. BUT, can performance gains be achieved by doing it?

(Security is also increased by compressing then encrypting)




Re: Compression TCP/IP
Jay wrote:
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If you consider that part of the TCP/IP stack is right.

Regards.

--

Jose Maria Lopez Hernandez
Director Tecnico de bgSEC
jkerouac@bgsec.com
bgSEC Seguridad y Consultoria de Sistemas Informaticos
http://www.bgsec.com
ESPAŅA

The only people for me are the mad ones -- the ones who are mad to live,
mad to talk, mad to be saved, desirous of everything at the same time,
the ones who never yawn or say a commonplace thing, but burn, burn, burn
like fabulous yellow Roman candles.
                 -- Jack Kerouac, "On the Road"


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