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netter router fuer dos

Hab nicht gesehen, ob das durchgekommen ist. Und es ist auch kein
Proxy, also nichts um vernuenftig gemeinsames Klicken im Web zu 
ermoeglichen, sowas solls allerdings fuer Windows geben.
Gemeinsames Klicken im Computerlabor via AOL.

Fand den File aber ganz lehrreich, Mischler ist der Autor und
@ www.mischler.com gibts das Programm:

Subject: Re: Tcp/ip & IPROUTE address Translation question
Date: 6 Dec 1996 00:25:38 GMT

>how does the IPROUTE software know which incoming packets should go to
>which internal address.

In general, by the same
(source address:source port, destination address:destination port)
tuples that would be used without translation.  The main difference
is that IPRoute chooses the external address and port for each
connection to/from the internal network, and translates the addresses
and port numbers as the packets enter and leave the router.

>I understand (atleast I think I do) that in a
>system without address translation, incoming packets are directed back
>to the right application based on the source address and port. But in
>an enviroment with address translation surely two internal user could
>assign the same port number for an external connection, and external
>site would not know anything about the source address as its been

Right.  Say user A and user B both connect to www.netscape.com's HTTPD
server (port 80).  They are running an IPRoute box with NAT configured
to assign all outgoing connections to IP address  User A's
internal source address and port is; user B's source
info is  IPRoute assigns a new external source port
to both connections on the single external IP address, let's say they
are 1597 and 1598.  So now the remote node sees the following:

User A (, www.netscape.com:80)
User B (, www.netscape.com:80)

You can see there is no problem for the remote server.  It has unique
information for each connection.  The IPRoute box won't have a problem
handling replies either because the external port numbers (destination
port numbers on replies) tell it which internal address and port should
be the true destination of each packet.

>If anyone could explain how this works, or point me in the direction
>of some info I'd be grateful.

There is a very obscure description of this in the IPRoute.txt file that
accompanies the software.  You can observe it in operation with the
"show nat <interface> status" and "show nat <interface> debug" commands.

Dave Mischler