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Home > Archive > alt.certification.network-plus > June 2003 > NAT & Proxy Server - Need Help
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NAT & Proxy Server - Need Help
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| Mark Rosenbaum 2003-06-28, 2:24 pm |
| I am studying for my N+ and am having a bit of difficulty understanding how
a NAT works, could someone please expain it and also maybe recommend a good
web site for basic and intermediate knowledge of a NAT.
Secondly, If I am not mistaken doesn't a proxy server just change the port
address that information is sent out on in layer 7 of the OSI model? Thing
is I don't understand why you would what to change the port number.
Thanks for the help
Mark Rosenbuam
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| 1. NAT - because there are so many computers out there connected to various
networks there are just not enough IP addresses for everyone, so we use NAT
Network Address Translation to change an external IP address to an internal
one (private).
EG.
Your company has an IP address of say 210.86.50.121 and you have 38
workstations on your internal network, then you could use nat to address
them 192.168.1.2 to 192.168.1.39. Each of these workstations would be
connected to the ouside world as 210.86.50.121 and when a message was
returned to them the NAT server would know which workstation to send the
message to. If you were someone on the internet and you pinged someone you
recieved a message form you would get 210.86.50.121 - the NAT server.
2. Proxy - This is done mostly as a security measure. Take it that HTTP
uses port 80, so when you ping an address it would look like
210.86.50.121:80 - that is the external address to the Proxy server. The
proxy server then convert this to say 8080 (a very common one) and that is
the address that the local workstations would connect to. This is done to
hide the internal nodes to the outside - particularly useful in keeping
script kiddie hackers out of ones network.
I hope that explains your questions in a manner you understand. I could go
a little more in-depth, but that is not necessary for Net+, and besides
there are a few whizzards out there who could probably explain it in betetr
terms.
--
RussS
MCP W2K Pro & Server, A+, Net+
http://www.techexams.net/
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>What is the significancy of the IP address 192.168.1.X? Do you
always use this IP address for NAT? I've noticed it used on other
systems, too.
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| Dave Watson 2003-06-30, 6:24 am |
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"pez74" <pzelonis74@yahoo.com> wrote in message
news:cc5ce92a.0306300127.61c88e1f@posting.google.com...
> >
> >What is the significancy of the IP address 192.168.1.X? Do you
> always use this IP address for NAT? I've noticed it used on other
> systems, too.
Hey, That's my IP address. Give it me back right now before I report you to
your ISP.
Dave.
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| 192.168.1. is just a common address that is the default for many different
brand switches.
IANA reserved 4 address ranges to be used in private networks, these
addresses won't appear on the Internet avoiding IP address conflicts:
- 10.0.0.0 through 10.255.255.255
- 172.16.0.0 through 172.31.255.255
- 192.168.0.0 through 192.168.255.255
- 169.254.0.1 through 169.254.255.254 (reserved for Automatic Private IP
Addressing)
--
RussS
MCP W2K Pro & Server, A+, Net+
http://www.techexams.net/
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