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From <oh...@cox.net>
Subject Re: Do any of the Tomcat LDAP-type realms support "no password" authentication?
Date Fri, 02 Dec 2011 01:54:48 GMT

---- "André Warnier" <aw@ice-sa.com> wrote: 
> ohaya@cox.net wrote:
> > ---- "André Warnier" <aw@ice-sa.com> wrote: 
> >> ohaya@cox.net wrote:
> >>> Hi,
> >>>
> >>> I'm new here, and hope that someone can help.
> >>>
> >>> I was wondering if any of the LDAP-type realms (e.g., JNDIRealm, etc.) support
an authentication mode where no password or credentials are required?  In other words, where
just a userID/username is presented, and if that userID/username is present in the LDAP, then
the user gets authenticated?
> >>>
> >> You have to be VERY specific here about what you mean, because this is a very
delicate area.
> >>
> >> If you mean : "does there exist any way by which Tomcat can authenticate a user,
without 
> >> forcing this user to go through a login dialog with userid and password ?"
> >> then the answer is : yes, several (*).  But the applicability of each depends
very much on 
> >> the exact circumstances.
> >>
> >> If you mean : "does there exist any /standard/ authentication mechanism in Tomcat
whereby, 
> >> /with/ a login dialog, the user could be authenticated without providing a password,

> >> although the authentication back-end (e.g. LDAP) has a non-empty password registered
for 
> >> that user ?"
> >> then the answer is no, definitely.  Because such a mechanism would be a HUGE
security 
> >> hole, so it is certainly not provided as any standard authentication framework.
> >> (which does not mean that you could not invent your own mechanism).
> >>
> >> Also, when you are mentioning LDAP, do you really mean the standard LDAP (which
is just 
> >> basically a database, and is not per se an "authentication mechanism"), or do
you mean 
> >> "Windows domain authentication, backed up by an Active Directory server" ?
> >> Or something else ?
> >>
> >> There is so much variation possible here, that it may be better to describe
what you want 
> >> to achieve really, rather than asking questions about this or that mechanism
right away.
> >>
> >>
> >> (*) for example, look here :
> >> http://tomcat.apache.org/tomcat-7.0-doc/windows-auth-howto.html
> >> http://waffle.codeplex.com/
> >> http://www.ioplex.com/jespa.html
> >>
> > 
> > 
> > Hi Andre,
> > 
> > Sorry.  I should have been clearer in my explanation and my question, so let me
try again.
> > 
> > Our configuration has an Apache in front of the Tomcat, with the Apache reverse-proxying
(using mod_proxy, for now) to the Tomcat.
> > 
> > In the Apache proxy, we do client-authenticated certificate authentication, and
we also have a web agent/module that authenticates the user into a commercial SSO product.
 After the user is authenticated, the requests that go to/get proxied to the Tomcat have some
HTTP headers, including a header containing the userID of the user that got authenticated
by the SSO product.
> > 
> > I've been working on Tomcat valve that does "ID assertion", i.e., when the code
in my valve sees the HTTP header with the authenticated userID, it "asserts" the user into
Tomcat.  
> > 
> > Specifically,  my valve code calls org.apache.catalina.connector.Request.setUserPrincipal(getPrincipal(paramRequest)),
where "paramRequest" is the org.apache.catalina.connector.Request object.
> > 
> > 
> > When I posted my message, I had just started on my valve code.  As I said, I'm kind
of new to Tomcat security, but at that time, I *thought* that after my valve did the setUserPrincipal(),
that the user had to somehow be authenticated into the Tomcat realm (i.e., that the asserted
userID had to actually exist in the Tomcat realm).
> > 
> > 
> > I've since gotten an initial version of my valve code kind of working, but I'm still
a little.  
> > 
> > I can get the userID from the request header and call the setUserPrincipal() in
the valve code successfully, and from some test JSP pages I use, I can see that when the JSP
calls request.getUserPrincipal(), it appears to return the asserted user.
> > 
> > 
> > The thing that is puzzling me is that, on my test Tomcat, I just have the default
realm (the one that uses tomcat-user.xml for the user base), with only the default set of
dummy users.
> > 
> > 
> > And yet, when I test with my valve and the test JSP, it appears that everything
just works, even when the userID that I assert is not in the Tomcat realm!
> > 
> > 
> > For example, I guess in the default realm, there's only a comple of users (tomcat,
etc.), but if I send a request into the Tomcat with a header with a userID of "foobar" (and
even though there is no user "foobar" in the Tomcat realm), things seem to work ok, i.e.,
my JSP displays "foobar" for request.getUserPrincipal().
> > 
> > 
> > Having said all of that, I guess that my question has changed somewhat.  Specifically,
now I'm wondering:  With what I described above, and with my valve as described above, does
the asserted user NOT have to be in the Tomcat realm at all?
> > 
> > 
> > It's almost like, with Tomcat, when my valve code calls setUserPrincipal(), Tomcat
doesn't "care" whether the user that I'm asserting actually exists or doesn't exist in the
Tomcat realm?
> > 
> > 
> > Again, as I said, I'm new, so I may  (and probably am) misunderstanding something
about how Tomcat security works...
> > 
> > 
> > Sorry for the longish post, but I hope that things are clearer now?
> > 
> 
> Better a long and clear post, than a short and obscure one.
> 
> Two things :
> 
> I am not really a Tomcat expert, and this will need to be corroborated by one of them,
but 
> it seems that I remember a not-too-long-ago thread in this same forum, in which it came

> out that if there is already a user-id known to Tomcat, it will not even bother to run
its 
> own authentication code.  That is said in non-expert terms, but I'm sure someone here
will 
> correct that if need be.
> 
> The other thing is that you may be doing a lot of work for nothing.
> If you would use either one of the mod_proxy_ajp or the mod_jk Apache module as a 
> connector to Tomcat, then this connector will automatically pass the authenticated Apache

> user to Tomcat with every request, and you would not need your Valve.
> Have a look at the TomcatAJP <Connector> description, attribute "tomcatAuthentication".
> http://tomcat.apache.org/tomcat-7.0-doc/config/ajp.html
> 
> This being said, make sure that the connection between Apache and Tomcat is reasonably

> secure (for example, within the same host or over an internal network), because the AJP

> protocol (although in part binary) is not itself encrypted.
> No user password is passed over it (only the user-id), but a hacker could in theory 
> intercept the packets, and replace one user-id by another.
> 


Hi Andre,

Thanks for that info re. AJP.  I will definitely take a look (test) that, as even if I/we
pursue the valve I'm working on, it'd be a nice thing to have as an option (e.g., if someone
doesn't want to use mod_ajp, they could use my valve, but if they use mod_ajp, then they wouldn't
need the valve!

If you can remember, can you either provide a link or maybe the subject for that thread you
referenced?  I'd be very interested in reviewing it.

Thanks again for all the great info!

Jim

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