What is NAT? - Networking

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Thread: What is NAT?

  1. What is NAT?

    Can someone please (without asking me to Google) explain simply and
    plainly what NAT is?

    Is it, basically, the mechanism that my router uses to forward TCP or
    UDP packets that come in to my router from the ISP to a specific machine
    on my internal network (and vice-versa)?
    --
    % Randy Yates % "With time with what you've learned,
    %% Fuquay-Varina, NC % they'll kiss the ground you walk
    %%% 919-577-9882 % upon."
    %%%% % '21st Century Man', *Time*, ELO
    http://home.earthlink.net/~yatescr

  2. Re: What is NAT?

    On 07/23/2007 05:26 PM, Randy Yates wrote:
    > Can someone please (without asking me to Google) explain simply and
    > plainly what NAT is?


    But, why would anyone over here will do your homework? What the hell do
    we expect you will do by knowing it, when you already are reluctant to
    learn and, or use Google?

    > Is it, basically, the mechanism that my router uses to forward TCP or
    > UDP packets that come in to my router from the ISP to a specific machine
    > on my internal network (and vice-versa)?


    Yep, almost yes; let me correct s/forward/translate/ or transpose the
    packets.

    BTW, here at
    http://www.netfilter.org/documentati...O-2.html#ss2.1 is
    a nice page about [S|D]NAT.

    --
    Dr Balwinder S "bsd" Dheeman Registered Linux User: #229709
    Anu'z Linux@HOME Machines: #168573, 170593, 259192
    Chandigarh, UT, 160062, India Gentoo, Fedora, Debian/FreeBSD/XP
    Home: http://cto.homelinux.net/~bsd/ Visit: http://counter.li.org/

  3. Re: What is NAT?

    On Mon, 23 Jul 2007, in the Usenet newsgroup comp.os.linux.networking, in
    article , Randy Yates wrote:

    >Can someone please (without asking me to Google) explain simply and
    >plainly what NAT is?


    Well, let's see... it's going on 12:40 MST, or almost 8 hours since
    you posted the "please google for me" request - and hitting that
    search engine would have provided the answer in a few seconds. But as
    you don't want to google, here's another suggestion:

    [compton /usr/share/HOWTO]$ zgrep -wl NAT N*
    NET3-4-HOWTO.gz
    NetMeeting-HOWTO.gz
    Networking-Overview-HOWTO.gz
    [compton /usr/share/HOWTO]$

    I know - that's to hard as well. Try this then:

    http://www.netfilter.org/documentation/HOWTO/

    [TXT] NAT-HOWTO.txt 24-Dec-2006 16:06 25K
    [TXT] netfilter-double-nat-HOWTO.txt 24-Dec-2006 16:06 9.4K
    [TXT] netfilter-extensions-HOWTO.txt 24-Dec-2006 16:06 79K
    [TXT] netfilter-hacking-HOWTO.txt 24-Dec-2006 16:06 84K
    [TXT] netfilter-mirror-HOWTO.txt 24-Dec-2006 16:06 8.1K
    [TXT] networking-concepts-HOWTO.txt 24-Dec-2006 16:06 28K
    [TXT] packet-filtering-HOWTO.txt 24-Dec-2006 16:06 52K

    >Is it, basically, the mechanism that my router uses to forward TCP or
    >UDP packets that come in to my router from the ISP to a specific machine
    >on my internal network (and vice-versa)?


    Network Address Translation - works at the IP level. Your router replaces
    your local address with it's own, BUT ONLY IN THE IP HEADERS. Your local
    address could still be in application level data.

    Old guy

  4. Re: What is NAT?

    > Can someone please (without asking me to Google) explain simply and
    > plainly what NAT is?


    Google is no good for that kind of thing. Try wikipedia instead:

    http://en.wikipedia.org/wiki/Network...ss_translation


    -- Stefan

  5. Re: What is NAT?

    Randy Yates wrote:

    >> If you want help from the people you call ****heads,

    >
    > No, I don't.


    Only if you actually want help.

    If you're just here trolling - you will be ignored - eventually.

  6. Re: What is NAT?

    Randy Yates wrote:
    > Can someone please (without asking me to Google) explain simply and
    > plainly what NAT is?
    >
    > Is it, basically, the mechanism that my router uses to forward TCP or
    > UDP packets that come in to my router from the ISP to a specific machine
    > on my internal network (and vice-versa)?


    Not really, although NAT is typically used in a router for that purpose.

    NAT is an acronym for "Network Address Translation". With NAT, individual
    nodes can have different IP addresses on one side of a router than they have
    on the other side.

    It is simply the mapping of an IP address to a new IP address.

    --
    Lew Pitcher

    Master Codewright & JOAT-in-training | Registered Linux User #112576
    http://pitcher.digitalfreehold.ca/ | GPG public key available by request
    ---------- Slackware - Because I know what I'm doing. ------


  7. Re: What is NAT?

    On 24 jul, 02:57, Lew Pitcher wrote:
    > Randy Yates wrote:
    > > Can someone please (without asking me to Google) explain simply and
    > > plainly what NAT is?

    >
    > > Is it, basically, the mechanism that my router uses to forward TCP or
    > > UDP packets that come in to my router from the ISP to a specific machine
    > > on my internal network (and vice-versa)?

    >
    > Not really, although NAT is typically used in a router for that purpose.
    >
    > NAT is an acronym for "Network Address Translation". With NAT, individual
    > nodes can have different IP addresses on one side of a router than they have
    > on the other side.
    >
    > It is simply the mapping of an IP address to a new IP address.
    >
    > --
    > Lew Pitcher
    >
    > Master Codewright & JOAT-in-training | Registered Linux User #112576http://pitcher.digitalfreehold.ca/ | GPG public key available by request
    > ---------- Slackware - Because I know what I'm doing. ------


    in google:
    define: NAT
    http://www.google.com/search?q=defin...-US:unofficial

    You get a list of short explanations of the term you are looking for,
    and tons of links if you want more detailed info. It takes about 2
    minutes and you can dig as deep as you want... don't know if the
    define stuff works with other search engines.

    Since you don't like to use google, I paste the top 4:

    # In computer networking, network address translation (NAT, also known
    as network masquerading or IP-masquerading) is a technique in which
    the source and/or destination addresses of IP packets are rewritten as
    they pass through a router or firewall. It is most commonly used to
    enable multiple hosts on a private network to access the Internet
    using a single public IP address. According to specifications, routers
    should not act in this way, but it is a convenient and widely-used
    technique. ...
    en.wikipedia.org/wiki/NAT

    # An Internet standard that enables a local-area network (LAN) to use
    one set of IP addresses for internal traffic usually private addresses
    and a second set of public addresses for external traffic. A NAT box/
    router/firewall is located where the LAN meets the Internet makes all
    necessary IP address translations.
    dedicated.sbcis.sbc.com/NDWS/faq/terms.jsp

    # Network Address Translation (NAT) is the translation of an Internet
    Protocol (IP) address used within one network to a different IP
    address known within another network. One network is designated as the
    inside network and the other is the outside.
    www.streamium.com/support/glossary.cfm

    # (Network Address Translation). A networking protocol that allows
    network of private IP address to be set up using a single real IP
    address. Using NAT, a local area network (LAN) can be set up with no
    special configuration of the Internet connection. To the Internet, the
    network looks like one computer, but on the LAN, each computer has its
    own internal IP address.
    www.indra.com/support/glossary.html


  8. Re: What is NAT?

    On Mon, 23 Jul 2007 15:58:06 -0400, Randy Yates rearranged some electrons
    to form:

    >
    > PS: There are reasons other than laziness not to use Google.


    Like what? Concerned that your instructor might recognize that you copied
    something from a Google hit to answer your homework question? However, if
    you're trying to learn something, I would recommend in the future that you
    leave the attitude at the door.

    Not only are you alienating the people you insulted, but the rest of the
    people that read this newsgroup. One of us may have the answer for your
    next homework assignment, but we may be relucutant to give it to you.


    --
    David M (dmacchiarolo)


  9. Re: What is NAT?

    On 2007-07-24, Tim Southerwood wrote:
    >
    > I can use Google in northern China up near the Mongolian border. Are you
    > trying to tell us that New Carolina isn't that advanced yet?


    I'm guessing it's North Carolina, not New.

    --keith

    --
    kkeller-usenet@wombat.san-francisco.ca.us
    (try just my userid to email me)
    AOLSFAQ=http://www.therockgarden.ca/aolsfaq.txt
    see X- headers for PGP signature information


  10. Re: What is NAT?

    Keith Keller wrote:

    > On 2007-07-24, Tim Southerwood wrote:
    >>
    >> I can use Google in northern China up near the Mongolian border. Are you
    >> trying to tell us that New Carolina isn't that advanced yet?

    >
    > I'm guessing it's North Carolina, not New.
    >
    > --keith
    >


    Sorry - I'm English ;->

    For some reason, our school geography lessons concentrated on S.America and
    rarely touched on the USA...



  11. Re: What is NAT?

    On Tue, 24 Jul 2007 16:00:16 +0100, Tim Southerwood wrote:

    > Keith Keller wrote:


    >> I'm guessing it's North Carolina, not New.


    > Sorry - I'm English ;->
    >
    > For some reason, our school geography lessons concentrated on S.America and
    > rarely touched on the USA...


    That's alright. We colonials were only good for paying taxes to the crown
    anyway ;-)


  12. Re: What is NAT?

    On Jul 23, 4:56 am, Randy Yates wrote:
    > Can someone please (without asking me to Google) explain simply and
    > plainly what NAT is?
    >
    > Is it, basically, the mechanism that my router uses to forward TCP or
    > UDP packets that come in to my router from the ISP to a specific machine
    > on my internal network (and vice-versa)?


    My son knew, from before the age of seven, that you don't ask someone
    what the definition of a word is while a dictionary is sitting right
    there on your table. What the hell is wrong with you?

    DS


  13. Re: What is NAT?

    David Schwartz writes:

    >On Jul 23, 4:56 am, Randy Yates wrote:
    >> Can someone please (without asking me to Google) explain simply and
    >> plainly what NAT is?
    >>
    >> Is it, basically, the mechanism that my router uses to forward TCP or
    >> UDP packets that come in to my router from the ISP to a specific machine
    >> on my internal network (and vice-versa)?


    >My son knew, from before the age of seven, that you don't ask someone
    >what the definition of a word is while a dictionary is sitting right
    >there on your table. What the hell is wrong with you?


    My complete Oxford English Dictionary--the largest and most complete
    dictionary of the english language-- has no such definition.
    Are you sure that your advice is worth a pile of dead gnats?

    Anyway to answer the original question, NAT is an acronym for Network
    Address Translation-- the router takes a packet from your machine with its
    internal address ( say 192.168.0.2, port number 80) and translates it to
    the address of the router itself ( 142.56.98.7) with a high port number (
    way 3080) and remembers that that port is associated with port 80 on
    192.168.0.2.

    t is a way of having the router with its external address pretend to be any
    one of the machines on the inside network.

    >DS



  14. Re: What is NAT?

    Unruh writes:
    > [...]
    > Anyway to answer the original question, NAT is an acronym for Network
    > Address Translation-- the router takes a packet from your machine with its
    > internal address ( say 192.168.0.2, port number 80) and translates it to
    > the address of the router itself ( 142.56.98.7) with a high port number (
    > way 3080) and remembers that that port is associated with port 80 on
    > 192.168.0.2.
    >
    > t is a way of having the router with its external address pretend to be any
    > one of the machines on the inside network.


    As with many names/acronyms, it sounds more intimidating than it
    really is.

    Thank you. I appreciate your sane, simple, informative response.
    --
    % Randy Yates % "Watching all the days go by...
    %% Fuquay-Varina, NC % Who are you and who am I?"
    %%% 919-577-9882 % 'Mission (A World Record)',
    %%%% % *A New World Record*, ELO
    http://home.earthlink.net/~yatescr

  15. Re: What is NAT?

    On Wed, 25 Jul 2007 18:15:54 +0000, Unruh wrote:

    >>My son knew, from before the age of seven, that you don't ask someone
    >>what the definition of a word is while a dictionary is sitting right
    >>there on your table. What the hell is wrong with you?

    >
    > My complete Oxford English Dictionary--the largest and most complete
    > dictionary of the english language-- has no such definition.
    > Are you sure that your advice is worth a pile of dead gnats?


    I think he was referring to wikipedia or google, or other computer
    accessible dictionary type stuff.

    sf

  16. Re: What is NAT?

    jellybean stonerfish writes:

    >On Wed, 25 Jul 2007 18:15:54 +0000, Unruh wrote:


    >>>My son knew, from before the age of seven, that you don't ask someone
    >>>what the definition of a word is while a dictionary is sitting right
    >>>there on your table. What the hell is wrong with you?

    >>
    >> My complete Oxford English Dictionary--the largest and most complete
    >> dictionary of the english language-- has no such definition.
    >> Are you sure that your advice is worth a pile of dead gnats?


    >I think he was referring to wikipedia or google, or other computer
    >accessible dictionary type stuff.


    I was pointing out to him that he was being stupid, rude, insulting and
    wrong. And neither wikipedia, google or other computer accessible
    dictionary type stuff are "a dictionary sitting right there on your table"



    >sf


  17. Re: What is NAT?

    Hello,

    Unruh wrote :
    >
    > Anyway to answer the original question, NAT is an acronym for Network
    > Address Translation-- the router takes a packet from your machine with its
    > internal address ( say 192.168.0.2, port number 80) and translates it to
    > the address of the router itself ( 142.56.98.7) with a high port number (
    > way 3080) and remembers that that port is associated with port 80 on
    > 192.168.0.2.
    >
    > it is a way of having the router with its external address pretend to be any
    > one of the machines on the inside network.


    What you describe is actually masquerading, which is only one - and
    probably the most common - of the many variations of NAT. Another common
    variation is "port forwarding", which changes the destination address
    according to the destination protocol and port. At large, NAT is any
    processing that takes a packet and changes its original source and/or
    destination address with whatever new address. Neither the original
    destination address nor the new source address need to belong to the NAT
    device.

    PS to the OP : how is this question specific to Linux ?

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