On 4 Jun 2002, at 22:38, AMD950 wrote:

> Question: why is it that when utilizing a proxy server, and
> checking my IP online, some sites reports the proxy server's
> address, yet others return my true IP?  TIA
>
> Ian Carmichael

  In general, a proxy server receives requests from your machine, and
re-issues them with itself as originator.  In practice, this has to
cope with two quirks:

1.  If your request is addressed to the proxy server, there needs to
be some way for your client software to specify what remote address
the proxy should re-issue the request to.  This often means that
either the client must use a different protocol to talk to the proxy
than if it was going direct, or that the client must think the proxy
is just a router/gateway and not know that it is a proxy.

2.  Some protocols -- especially those that are encoded or encrypted -
- carry the origin IP address within the protocol data, as well as in
the IP traffic headers.  Most proxy implementations that pretend to
be gateways (see #1) don't know about internal details of specific
protocols.  They can change the packet headers to show the proxy as
the origin, but the real origin address is still present in the
protocol data.

David Gillett

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