Q: Does This make sense? A: Probably not. NetWebClient & Temp Internet Files

[BColladay]

We use NetWebClient to access a web service to process Credit Cards. We had a client recently that was getting an internet connectivity issue fro Credit Card Processing on some machines.  I had them try the same web service, from the same machine from Internet Exploder and it worked fine.

Perplexed...I had them run WireShark to see the traffic, normal traffic from the browser, from the NetWebClient process they got the message Cache Access Denied.  Ok great! an error.

They have an internet content filter in place so we contacted them, they said, "not our error" but they said to try cleaning out the Temporary internet files cache and associated files...knowing this wouldn't work, I tried it.  For some reason it worked...any idea why this would work with nettalk?

[Bruce]

my guess is that they're running a proxy somewhere which is blocking the traffic from the WebClient (not sure why). Using it from IE "opened" the proxy, whereafter the WebClient worked. I don't think the clearing-cache would have had anything to do with it. My guess is that the WebClient may stop working after a bit.

cheers
Bruce

[BColladay]

Actually I was misinformed, it still doesn't work, what he was telling me was that he turned of the proxy to make it work.  He added the domain of the web service to the whitelist on the proxy and it is still not working.

So it stands that on the same machine you can access the web service with an IE or any browser, but if you run our application using WebClient it gets the Access denied error from the proxy.

On What planet does this make sense?  (BTW this is NT 4)  they haven't upgraded to our latest version.

[Bruce]

Hi Ben,

Ok, this actually does make some sense - more than the last report.

my guess is
a) the proxy requires authentication. (Which NT does automatically using the IE settings).

b) your program uses a user-agent header which identifies it as IE6. (This has changed in 5.22 to something more recent - Chrome I think.)

c) because your program identifies itself as IE, the proxy attempts "NTLM" Authentication (which pretty much only Microsoft support). NetTalk supports Basic authentication (and in NT5 Digest authentication as well).

One solution worthy of effort - set the web._userAgent string before doing the POST or FETCH. for example;

  web._UserAgent = 'Mozilla/5.0 (Windows; U; Windows NT 6.0; en-US) AppleWebKit/534.16 (KHTML, like Gecko) Chrome/10.0.648.204 Safari/534.16' ! chrome

or

  web._UserAgent = 'Mozilla/5.0 (Windows; U; Windows NT 6.0; en-US; rv:1.9.2.16) Gecko/20110319 Firefox/3.6.16 ( .NET CLR 3.5.30729; .NET4.0C)' ! firefox 3.6

Cheers
Bruce