which port is beeing used with get URL?

Trevor DeVore lists at mangomultimedia.com
Sat May 20 05:55:50 EDT 2017

On Fri, May 19, 2017 at 3:40 AM, Tiemo Hollmann TB via use-livecode <
use-livecode at lists.runrev.com> wrote:

> LC6 and 8. Again and again I have customers, where my program doesn't gets
> an internet connection with standard "put URL foo into res". This happens
> only at "institutional customers" with "bigger" networks, obviously with
> proxy servers, firewalls, etc. On "private" PCs I never happen this. The
> user can setup the proxy credentials in my program, that is ok for some
> customers. At other customers my program still doesn't gets access to the
> internet and often the admin of the customer doesn't find the reason what
> is
> blocking my program. Usually most firewalls pop up with a request, if they
> are blocking a new program, but in these cases the firewalls keep silent,
> so
> it is hard to find the reason.
> ...
> Are there any ideas from your experience, what and how to check for to find
> the blocking factor in a customer network?

Over the years I've had to use lots of logging and error reporting in order
to get to the bottom of internet issues. I have a way for users to turn on
logging and all of the ulLogIt messages that liburl generates are logged to
a file (just intercept it in a frontscript).

In the current version of libUrl I'm aware of two major issues that can
affect users on a corporate network -

1. If the network uses a proxy server for HTTPS traffic then the CONNECT
protocol will be used. libURL swallows up the headers you send along with
your URL, however. If your url request requires headers, it is using the
https protocol, and the request is going through a proxy then the request
will fail.

2. If the network requires NTLM authentication then the request will fail.
When I've used libURL in the past I had an external that Altuit provided
years ago. tsNet has NTLM built in and I recently switched to tsNet because
of [1]. The current version of tsNet doesn't pick up proxy information on
some platforms and doesn't report 40x errors the same way as libUrl but
those issues have been addressed for the next release.

It may also be that the IT department has to whitelist the domains that our
desktop app is trying to connect. I provide a help document for my app that
tells IT departments the domains that the app connects to.

Trevor DeVore

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