[Opensim-dev] [REX] [Fwd: User Authentication]
Charles Krinke
cfk at pacbell.net
Tue Feb 24 00:02:59 UTC 2009
Well, I suppose that since we can discern which viewer logs in via the UserServer, we can allow additional features for some viewers that dont exist for others.
Dont know if that simplifies or complicates the problem, however.
Charles
________________________________
From: Diva Canto <diva at metaverseink.com>
To: opensim-dev at lists.berlios.de
Sent: Monday, February 23, 2009 3:52:29 PM
Subject: Re: [Opensim-dev] [REX] [Fwd: User Authentication]
"However, this would currently have to happen purely as communication
between backend services since we can't change the viewer."
This doesn't solve the man-in-the-middle problem in OSGrid itself,
which needs to be solved too, urgently.
I think my proposal does.
Crista
Hurliman, John wrote:
A RADIUS server is a solution to the problem of authentication. OpenID is a solution for federated identity, and plays nicely with any authentication solution you want to use. I think the description of this particular problem is closer to identity verification across administrative domains than defining a common login protocol, so the OpenID + token systems sound like the right approach. However, this would currently have to happen purely as communication between backend services since we can't change the viewer. A possible flow might be:
(OSGrid)->(UCI) "User http://www.osgrid.org/users/Charles_Krinke is teleporting to you. His token is abcdef"
(UCI)->(http://www.osgrid.org/users/Charles_Krinke) "I have the token abcdef, is that a valid session token for Charles?"
(UCI)<-(http://www.osgrid.org/users/Charles_Krinke) "Yes it is"
(OSGrid)<-(UCI) "That worked, thanks. Teleport is finished"
Notice that Charles happens to have his identity at OSGrid, but that's not a requirement of the exchange. It could just as easily been an identity from another grid, which will be useful for teleporting from UCI to ScienceSim.
John
-----Original Message-----
From: opensim-dev-bounces at lists.berlios.de [mailto:opensim-dev-
bounces at lists.berlios.de] On Behalf Of Mark Malewski
Sent: Monday, February 23, 2009 3:04 PM
To: Opensim-dev at lists.berlios.de
Subject: Re: [Opensim-dev] [REX] [Fwd: User Authentication]
Crista,
The bottom line question in my email, phrased in OpenID terminology,
is whether we
can use the Viewer's IP address as the token.
My question is, would you really want to use the Viewer's IP address as
the token? What IP address would it specifically use?
If a user were on an internal LAN, would it use the 192.168.1.x IP
address (local internal LAN address) or 10.x.x.x? or 172.x.x.x?
Or would it use the external routable IP address (from the ISP)? If
that were the case, then wouldn't 2 viewers that are accessing a server
>from the same location (for example a library, or school, or
work/office) where multiple computers on the same internal LAN would try
to connect to an external grid server, then wouldn't the viewer's all
have the same IP address?
Keep in mind, that most users are using NAT behind their firewall, so
what IP address would you even use for the token?
A better address would be the hostname address (hostname at domain.com).
This way each and every machine would always hava a unique hostname, and
it's tied to a specifc domain (whether it's an internal domain, a LAN,
or even the WAN/ISP domain name given by your local ISP, such as a local
comcast user:
hostname at be-70-ar01.area1.il.chicago.comcast.net
It might make more sense to use hostname instead of an IP address. So
maybe use the machine's full FQDN hostname as the token?
I still think a RADIUS server would be the best bet (the solution I
described in the message below), as the best possible longterm solution
to this problem.
We would probably need to create some type of "RADIUS" module for
OpenSim.
Mark
On Mon, Feb 23, 2009 at 3:29 PM, Mark Malewski <mark.malewski at gmail.com>
wrote:
On Mon, Feb 23, 2009 at 3:28 PM, Mark Malewski
<mark.malewski at gmail.com> wrote:
Crista,
Sounds like you are on the right track. Sounds like a very
"logical" process, but why not use something like 802.1x/EAP?
> So, what can we do to detect the legitimacy of agents?
Instead of a "Finnish Magic", why not use 802.1x and use a
RADIUS server for standard authentication?
Using simple 802.1x, the authenticator sends an "EAP-
Request/Identity" packet to the supplicant as soon as it detects that
the link is active (the user has associated with the grid/radius
server).
1. The supplicant sends an "EAP-Response/Identity" packet
to the authenticator, which is then passed on to the authentication
(RADIUS) server.
2. The authentication server sends back a challenge to
the authenticator, such as with a token password system. The
authenticator unpacks this from IP and repackages it into EAPOL and
sends it to the supplicant. Different authentication methods will vary
this message and the total number of messages. EAP supports client-only
authentication and strong mutual authentication. Only strong mutual
authentication is considered appropriate for the virtual world case.
3. The supplicant responds to the challenge via the
authenticator and passes the response onto the authentication server.
4. If the supplicant provides proper identity, the
authentication server responds with a success message, which is then
passed onto the supplicant. The authenticator now allows access to the
LAN- - possibly restricted based on attributes that came back from the
authentication server. For example, the authenticator might switch the
supplicant to a particular virtual LAN or install a set of firewall
rules.
802.1x is a standard, and many wireless LAN vendors have
latched onto 802.1x standard to help authenticate and secure both wired
and wireless LANs. The greatest feature of 802.1x is interoperability.
It would seem to make sense to just use 802.1x
authentication, EAP is supposed to head off proprietary authentication
systems and let everything from passwords to challenge-response tokens
and public-key infrastructure certificates all work smoothly.
Why not just use a standard RADIUS server as the
authentication server? With 802.1x, the user or client that wants to be
authenticated would be called a "supplicant". The actual server doing
the authentication (typically a RADIUS server) is called the
authentication server. The device in between (such as a wireless access
point, or any region/grid server) is called the "authenticator". One of
the key points is that the authenticator can be simple and dumb, all of
the "brains" have to be in the supplicant and the authentication server.
Each Grid could run their own separate RADIUS server, and
user groups could be setup to allow users to "hypergrid" between grids
(securely). [By setting up REALMS between Grids]
Each grid would be responsible for checking the "legitimacy"
of it's users (via E-mail confirmation, etc.) and if any user was "up to
no good" then their user ID can be disabled, and their IP address can be
blocked (by the RADIUS server).
http://freeradius.org/
Using a standard FreeRADIUS server would make it extremely
easy for Grid Administrators to Administer User accounts. RADIUS would
provide centralized access, authentication and accounting management for
users of the Grid.
http://en.wikipedia.org/wiki/RADIUS
If someone attempted to "hijack" a secure session, the
RADIUS server checks that the information is correct using
authentication schemes like PAP, CHAP or EAP. The RADIUS server than
returns one of three responses ("Yea", "Nay", or "Challenge").
The "Access Challenge" requests additional information from
the user (such as a secondary password, or a PIN number, mother's maiden
name, secret password, or a token or even a secureID card, biometrics,
etc.)
Similar to how a web-based online banking system (like Bank
of America) works. If you are using the same computer all the time, it
only asks for your username and password. If you attempt to login from
a new or different computer, then it kicks back an Access Challenge, and
asks you for additional information (like a secret password, or a PIN,
or to verify your mother's maiden name, or any of several challenge
passwords that only the actual user would know).
If the Challenge is successful, then the secure tunnel is
established between the user machine and the RADIUS server (and access
credentials are completely hidden).
By using RADIUS, we could also grant users access by groups.
There could be an "Administrators" groups setup, and "Moderator" groups,
and "Peace Keepers" groups, and various groups with certain permissions
setup.
Also certain information is stored in the RADIUS server (IP
address of the user, maximum length that the user may remain connected,
an access list, priority queue or other restrictions on a user's access,
VLAN parameters, QoS parameters, etc.)
RADIUS is commonly used to facilitate roaming between ISPs,
for example by companies which provide a single global set of
credentials that are usable on many public networks. RADIUS facilitates
this by the use of realms, which identify where the RADIUS server should
forward the AAA requests for processing.
A realm is commonly appended to a user's user name and
delimited with an '@' sign, resembling an email address domain name.
This is known a postfix notation for the realm. Another common usage is
prefix notation, which involves prepending the realm to the username and
using '\' as a delimiter. Modern RADIUS servers allow any character to
be used as a realm delimiter, although in practice '@' and '\' are
usually used.
Realms can also be compounded using both prefix and postfix
notation, to allow for complicated roaming scenarios; for example,
somedomain.com <http://somedomain.com/> \username at anotherdomain.com
could be a valid username with two realms.
Although realms often resemble email domains, it is
important to note that realms are in fact arbitrary text and need not
contain real domain names.
So users from different Grids could roam freely between
"partnering" Grid servers using realms.
Proxy operations
When a RADIUS server receives an AAA request for a user name
containing a realm, the server will reference a table of configured
realms. If the realm is known, the server will then proxy the request to
the configured home server for that domain. The behaviour of the
proxying server regarding the removal of the realm from the request
("stripping") is configuration-dependent on most servers. In addition,
the proxying server can be configured to add, remove or rewrite AAA
requests when they are proxied.
I believe the first step would be to get a RADIUS server
setup and working, and then work on setting up two grids together (using
REALM between the two RADIUS servers) and then once this could be done,
then later additional grids could be "trusted" and allowed onto the
network. So users could roam freely between the "trusted grids".
If a user was reported to the Grid Owner (as being an
"abusive user") then the Grid owner would suspend that user's account,
and send an "abuse notification" to the Grid Owner (that the user has
violated the Terms of Service for the Grid). Basically just "pull the
plug" on that user's account, and kick them off the grid, and ban their
computer & IP address.
It would make it extremely easy for "policing" the Grid, and
any users that want "Secure Inter-Grid" handshakes would just join the
REALM network.
Mark
P.S. If you need some help with this, I'm sure we can sit
down and discuss it a bit, and set something up as a "demo" grid as to
how this could be done. Then later other Grids (like OS Grid, and
various others) could join the REALM grid network.
On Mon, Feb 23, 2009 at 2:19 PM, Toni Alatalo
<antont at kyperjokki.fi> wrote:
this kinda sounds like trying to achieve what rexauth
does, no?
perhaps someone could write how it is w.r.t to that
case? i might be
able, but too tired now and probably busy tomorrow.
also John Hurliman is planning new auth stuff with
openid and some
openid related token thing (i forgot the name) which
is basically 'same
as rexauth but standards instead of Finnish magic',
like he said the
other day :) .. so perhaps he replies his plan there,
seems to be online
at least.
~Toni
--~--~---------~--~----~------------~-------~--~----~
this list: http://groups.google.com/group/realxtend
realXtend home page: http://www.realxtend.org/
-~----------~----~----~----~------~----~------~--~---
Hi,
I'm about to start tightening the ropes for the
Hypergrid in order to
make it safer, and also make safer some loose ends of
OpenSim without
HG, and I would appreciate feedback on this.
The first issue that needs to be addressed is the
issue of user
authentication. The regions need to be able to verify
that the agent
that claims to be representing
Charles.Krinke at osgrid.org is, indeed,
representing Charles.Krinke at osgrid.org. (As you know,
right now this
is... err... a bit overlooked... *coughs*... and not
just in the HG...
*more coughs*).
Having looked at OpenID, I came to the conclusion that
it's not enough
to know that osgrid.org <http://osgrid.org/> has a
user named "Charles Krinke", and we
certainly don't want Charles to be constantly typing
his password
everytime he moves; the region needs to know that this
user is already
logged in to the system AND the region also needs to
know that the agent
that is representing this user is a legitimate agent.
OK, so the part about being logged in is easy; the
user server already
knows that, to some approximation.
However, the part about the agent being legitimate is
a bit more tricky.
Here's the bad thing that can happen: Charles logs in
to OSgrid, and TPs
to this intriguing region called "Sports Illuminated
Swimming Suite
Edition". That region happens to be up to no good. It
grabs Charles
current notion of identity (all the current
identifiers we use), it
crashes Charles' viewer so that the user server never
knows about it,
and proceeds to impersonate Charles using all those
stolen identifiers;
for example, it can go back to Charles's regions and
erase them
completely pretending to be Charles.
So, what can we do to detect the legitimacy of agents?
Having scratched my head over this, I came to the
conclusion that the
most promising element that can be used to identify
agents is the
Viewer's EndPoint. This is what happens down in the
LLUDPServer (I'm
sure something similar happens in other viewers'
packet handlers):
if (packet != null)
{
if (packet.Type ==
PacketType.UseCircuitCode)
AddNewClient((UseCircuitCodePacket)packet, epSender,
epProxy);
else
ProcessInPacket(packet, epSender);
}
The EndPoint epSender comes directly from the socket
and I'm assuming it
can't be faked, at least the IP part. Is this correct?
This is a
critical assumption.
So, back to the "Sports Illuminated" scenario: that
sim would then try
to launch an agent at Charles' region. It can fake
everything except
being Charles' viewer machine. When Charles' region
does that code
above, it asks the User server for authentication of
an agent with all
those identifiers and the given EndPoint, and the User
server tells back
that Charles wasn't using that EndPoint to start with,
so the
authentication fails, and an alarm is rang.
Thoughts?
Crista
Disclaimer: I'm not an expert in security, I'm just
using my brain in
context.
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