Proxy server?

[Gary]

I've seen examples for HTTP and FTP use, but not for simply any TCP data on
any port, which is what I require. Can anyone please point me in the right
direction?

TIA

[Diez B. Roggisch]

Gary wrote:

I've seen examples for HTTP and FTP use, but not for simply any TCP data
on any port, which is what I require. Can anyone please point me in the
right direction?

For what? How to use such a thing, a transparent proxy? There is nothing to
it, just plug it between your router and the internet, that's all.

Or do you want to know how to capture all traffic using some other process,
for analysis? Use wireshark.

Diez

[Gary]

"Diez B. Roggisch" <de***@nospam.web.dewrote in message
news:6f************@mid.uni-berlin.de...

Gary wrote:

For what?

A non-transparent proxy, for anonymity purposes only.

[Diez B. Roggisch]

Gary schrieb:

"Diez B. Roggisch" <de***@nospam.web.dewrote in message
news:6f************@mid.uni-berlin.de...

>Gary wrote:

>For what?

A non-transparent proxy, for anonymity purposes only.

You can't make any TCP/IP communication run through a proxy, unless it's
transparent.

HTTP (and maybe FTP, I personally don't know) have that built-in, and of
course anything that builds upon them (SOAP, XMLRPC).
But e.g. CORBA or bittorrent or .... don't support that.

You can try and install TOR or use it. It is a transparent proxy:

http://wiki.noreply.org/noreply/TheO...ansparentProxy

Diez

[Gary]

"Diez B. Roggisch" <de***@nospam.web.dewrote in message
news:6f************@mid.uni-berlin.de...

Gary schrieb:

"Diez B. Roggisch" <de***@nospam.web.dewrote in message
news:6f************@mid.uni-berlin.de...

You can't make any TCP/IP communication run through a proxy, unless it's
transparent.

Thanks for all the info.

I'm puzzled though that a such a transaction isn't possible by rewriting the
headers. So client X connects to my PS, which passes on the data to the
target but with the header changed to indicate the PS as the original
source. The intended target responds to the PS, this is then resent to
client X with the header modified so that the transaction appears
transparent. So it's *effectively* transparent target>client but
non-transparent client>target, if you see what I mean.

Can you please explain why this wouldn't work?

Thanks,
Gary

[Heiko Wundram]

Am Mittwoch, 30. Juli 2008 13:48:08 schrieb Gary:

"Diez B. Roggisch" <de***@nospam.web.dewrote in message
news:6f************@mid.uni-berlin.de...

Gary schrieb:

"Diez B. Roggisch" <de***@nospam.web.dewrote in message
news:6f************@mid.uni-berlin.de...

You can't make any TCP/IP communication run through a proxy, unless it's
transparent.

Thanks for all the info.

This is not entirely true. There are libc-plugins (i.e. LD_PRELOAD hacks)
which use SOCKS (which is a generic proxying protocol for [TCP/]IP) to
redirect all locally originating TCP/IP traffic _which is managed through the
socket interface of the libc_ in the application that you applied the
LD_PRELOAD hack to through a specified SOCKS-proxy (this should capture
pretty much everything, except for communication originating in the
*nix-kernel itself). I seem to recall that something similar exists for
WinSock, but I wouldn't know for sure.

Check the web for documentation on setting up a SOCKS proxy, and for the
respective libc-plugins or WinSock SOCKS "hack".

If you cannot make the user use SOCKS through a means like this (in which case
there has to be no application support) or by instructing a specific
application to use a SOCKS proxy directly (which all browsers can out of the
box AFAIK), and you don't have the possibility to put yourself somewhere in
the middle by means of a transparent proxy (i.e., a firewall applicance which
does this; I seem to recall that there was some FreeBSD-based software which
basically did just this kind of transparent proxying for a network), you're
out of luck, just like Diez said.

--
Heiko Wundram