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Conference noted::seal

Title:SEAL
Moderator:GALVIA::SMITH
Created:Mon Mar 21 1994
Last Modified:Fri Jun 06 1997
Last Successful Update:Fri Jun 06 1997
Number of topics:1989
Total number of notes:8209

1773.0. "Network Address Translation (MAX value)?" by TENNIS::KAM (AltaVista Software 714/261-4133 DTN 535.4133) Wed Feb 05 1997 03:37

The AltaVista Firewall can be configured to hide all internal host addresses 
from the external (untrusted) network. Addresses on outgoing mail messages 
are rewritten to hide host names -- typically, the host name is replaced by 
the name of the domain only.

*
* The AV Firewall maps the internal addresses to the address of the Domain
* Name at the Firewall.  What's the MAX # of addresses on the Blue Net that
* can be mapped to the Firewall Domain Name address?
* Is there any such upper-limit?
    
    	Regards,
    
T.RTitleUserPersonal
Name
DateLines
1773.1BIGUN::nessus.cao.dec.com::MayneWake up, time to dieThu Feb 06 1997 22:4812
To distill hundreds of pages of sendmail book to one line, address rewriting 
essentially works (or can be made to work) like this:

	Rewrite "From:" addresses of the form user@* to [email protected]

The maximum number of addresses is therefore anything that matches *, which is 
essentially infinite.

If you feel uneasy with this, you might want to be a bit more explicit about 
what you want.

PJDM
1773.2TENNIS::KAMAltaVista Software 714/261-4133 DTN 535.4133Sat Feb 08 1997 02:3224
    Some of our Firewall Competitors are advertising true NAT (Network
    Address Translation).  On the exterior interface of the firewall they
    can assign a pool of IP addresses e.g. 1-x.  On the Blue Net you can
    have y hosts, where y > x.  Then when a host on the blue net attempts
    to communicate through the firewall they will be assigned one of the IP
    addresses from 1-x.
    
    The AltaVista Firewall has one IP address at the exterior interface and
    all Blue net addresses get mapped to this address.
    
    "7.12. Network Address Translation
     The AltaVista Firewall for NT can be configured to hide all internal
     host addresses from the external (untrusted) network. Addresses on
     outgoing mail messages are rewritten to hide host names -- typically,
     the host name is replaced by the name of the domain only."
    
    A customer asked if it was possible to saturate the Network Address
    Translation that we do e.g., eventually a host on the Blue net wouldn't
    be mapped to the exterior IP address.
    
    This is the FUD that our Competition is spreading about us.
    
    	Regards,
    
1773.3confusion?ANNECY::HOTCHKISSTue Feb 11 1997 06:587
    why is this FUD?It's true.I think you are confusing address translation
    at the IP level with hiding mail addresses by changing them.If you want
    address translation at the IP level,then don't use our firewall - use
    either some sort of box like PIX(together with its 'features') or hide
    ALL the addresses(even illegal ones) using wired proxies(obtainable
    from our web site (but no GUI for the visually impaired ;-))
    btw - read rfc1919 too