[jcifs] Java applet and NTLM proxy authentication
aw at ice-sa.com
Fri Feb 27 17:44:09 GMT 2009
I posted this before on the Tomcat list without too much success.
I hope this is a better place.
As a preamble, I am by now fairly versed in Tomcat Java server-side NTLM
authentication (à la jCIFS/Jespa), but this is another animal : it's on
the browser side.
In our application, we have a html form allowing users to upload several
files together, as a "collection", to a webserver. The html form itself
contains some descriptive text input fields; the multiple file-upload is
provided by a Java applet embedded in the page, which allows users to
select local workstation files which should be uploaded to the server as
a set, together with the static form input fields values. It is this
applet (not the html form) which actually does the HTTP POST-ing to the
server of the files, one file/one POST at a time, each POST containing
one file plus a copy of the html input field values.
To make the POST, the applet picks up from the browser the proxy
settings if any, and uses them when it creates its own HTTP connection
to the server, via the org.apache.commons.httpclient.* packages
(HttpClient, method.* etc..).
It all works fine using IE and Firefox, whether the browser/customer is
behind a corporate proxy or not.
Only in one recent case, it does not.
In that particular case, the browser is IE, and the users are behind a
corporate outgoing proxy server which requires NTLM authentication on
the part of the client.
The browser is of course NTLM-authenticated with this proxy, since
otherwise it could never go through the proxy and fetch our html form in
the first place.
However, when the applet later tries to do a POST to the same server
whence the form came from, it receives a 401 response back from the
proxy. This 401 response tells the client (in this case the applet),
that it must authenticate via the NTLM method.
Unfortunately, the Java applet and its HttpClient do not seem to
magically pick up the containing browser's credentials and to
automatically add them to the POST request they are doing to the same
webserver, which I would have considered nifty. Sigh.
So now the question is : what do I have to do to my applet, that it
would authenticate properly to that proxy, using the NTLM credentials of
the browser it is living inside of, or using the credentials of the
workstation in which the containing browser lives ?
Secondary question : is this even possible ?
If anyone is sufficiently interested, there is a web demo site where
this can all be seen, and if you happen to be behind one such proxy
requiring NTLM authentication, you can also see (in the browser's Java
console) in detail what happens.
Thankful in advance for any hints about where to start looking,
As complementary information to my own questions above, I have already
read the document located here :
However, that does not seem to fit the bill, in the sense that the
method outlined there (using the jCIFS library) requires finally a call
like this :
new AuthScope("myserver", -1),
new NTCredentials("username", "password", "MYSERVER", "MYDOMAIN"));
which implies seemingly that I would have to present an authentication
dialog to the user and ask them to enter their user-id and password,
then submit these to the NTCredentials constructor.
This is marketing-wise impossible, since the user (via his IE browser)
is already authenticated in his own Windows/NTLM domain (and to the
proxy), and furthermore he is so transparently. It would thus be
impossible for me to "sell" the idea that they need to re-enter their
credentials just to use this facet of the application.
(I am also not quite sure how I would get the "DOMAIN" information from
within my applet.)
(It is also quite impossible to sell to the security people, that I
would, in my applet, be able to get hold of the user's password for
their domain account).
What I would like is some method by which the Java applet can pick up
this information from the browser it is running inside of, since that
browser /is/ already authenticated.
If that is impossible, I am afraid that instead of using the Java applet
to do both the local file selection and the POST submission to the
server, I'll have to merely do the file selection, pass the list back to
submission via an XMLHttpRequest at that level (supposing of course that
this object, at least under IE, allows for NTLM authentication; but I
think it does, or should).
Also maybe to dampen some ideas, I don't think I can sell to my customer
a 3-digit $ license for each of their workstations..
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