From: "Nadav Har'El" <[EMAIL PROTECTED]>
> On Tue, Apr 09, 2002, Eli Marmor wrote about "Re: OT: Transparent Proxies
in Israel":
> > But back to the original question: Can anybody list the ISP's that
> > don't use transparent proxies, even not for ADSL users who access
> > foreign (long distance) sites?
>
> No, I never did such research. When I was connected to Netvision's ADSL
> it looked like we did not have a transparent proxy, but I'm not sure.
> In Barak's connection, I did notice a transparent proxy in place.
>

I think that even if the ISP run transparent proxy, or actually any kind of
HTTP proxy, they should query the server in any case - to see if the content
is modified. If it does, it redownloads the content, and if not, it serves
from cache. In any case, it shouldn't serve old data without checking first.

I'm connected to BezeqInt ADSL, and it looks like they do have a transparent
proxy, and it works correctly. I did some testing:

[sagi@domino sagi]$ telnet sagi.org 80
Trying 208.38.141.10...
Connected to sagi.org.
Escape character is '^]'.
GET http://sagi.org/ctest.html HTTP/1.0

HTTP/1.0 200 OK
Age: 0
Date: Tue, 09 Apr 2002 08:40:04 GMT
Content-Length: 5
Content-Type: text/html
Server: Apache/1.3.19 (Unix) PHP/4.0.6 FrontPage/5.0.2.2510
Last-Modified: Tue, 09 Apr 2002 08:46:39 GMT
ETag: "16bdf8-5-3cb2aa6f"
Via: 1.1 proxy-ptk-primary (NetCache NetApp/5.2.1R1D3)

test
Connection closed by foreign host.

Apache log: 212.179.233.155 - - [09/Apr/2002:04:47:26 -0400] "GET
/ctest.html HTTP/1.1" 200 5 "-" "-"

Change file
[sagi@domino sagi]$ telnet sagi.org 80
Trying 208.38.141.10...
Connected to sagi.org.
Escape character is '^]'.
GET http://sagi.org/ctest.html HTTP/1.0

HTTP/1.0 200 OK
Age: 0
Date: Tue, 09 Apr 2002 08:40:28 GMT
Content-Length: 7
Content-Type: text/html
Server: Apache/1.3.19 (Unix) PHP/4.0.6 FrontPage/5.0.2.2510
Last-Modified: Tue, 09 Apr 2002 08:47:39 GMT
ETag: "16bdf8-7-3cb2aaab"
Via: 1.1 proxy-ptk-primary (NetCache NetApp/5.2.1R1D3)

test 2
Connection closed by foreign host.

Apache log: 212.179.233.155 - - [09/Apr/2002:04:47:50 -0400] "GET
/ctest.html HTTP/1.1" 200 7 "-" "-"

Didn't change, trying to fetch the same file again:
[sagi@domino sagi]$ telnet sagi.org 80
Trying 208.38.141.10...
Connected to sagi.org.
Escape character is '^]'.
GET http://sagi.org/ctest.html HTTP/1.0

HTTP/1.0 200 OK
Age: 0
Accept-Ranges: bytes
Date: Tue, 09 Apr 2002 08:40:56 GMT
Content-Length: 7
Content-Type: text/html
Server: Apache/1.3.19 (Unix) PHP/4.0.6 FrontPage/5.0.2.2510
Last-Modified: Tue, 09 Apr 2002 08:47:39 GMT
ETag: "16bdf8-7-3cb2aaab"
Via: 1.1 proxy-ptk-primary (NetCache NetApp/5.2.1R1D3)

test 2
Connection closed by foreign host.
[sagi@domino sagi]$

Apache log: 212.179.233.155 - - [09/Apr/2002:04:48:18 -0400] "GET
/ctest.html HTTP/1.1" 304 - "-" "-"

As you can see, it contacted the server anyway, to see if the data was
modified. Only after getting 304 header it served the content from cache..

Sagi



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