Practical Distributed Authorization for GARA
Andy Adamson and Olga KornievskaiaCenter for Information Technology Integration
University of Michigan, USA
Outline
• Background and motivation
• Security architecture of the current scheme
• Design of the authorization framework
• Modified authentication mechanism
• Video clip of the demo
• Reservation flow walk through
Background
• Grid computing is an initiative for advancement of distributed computing that enables flexible sharing of resources distributed among administrative domains
• GARA: General-purpose Architecture for Reservation and Allocation: Quality of Service reservation mechanism for different types of resources
• Project partners: University of Michigan (Physics, CITI), European Organization for Nuclear Research (CERN), Argonne National Laboratory (ANL), Merit, and others…
End to End Performance• Reliable high-speed end to end network services
are important to scientific collaborators– Video, audio, large data transfers
• Long haul networks demonstrate good performance due to overprovisioning
• The Last-mile is often a network bottleneck• Reliable end-to-end network service is achieved
by reserving network resources within end-point institution networks, coupled with the good performance of overprovisioned long haul networks.
Automated network reservation
• QoS functionality is a common feature in network hardware
• QoS configuration is currently done by hand• We address the need for an automated network
reservation system• Security of all communications is vital• Difficult security problem due to cross-domain
nature of end-to-end network resource allocation
Project based on Globus GARA• GARA is a GRID network reservation service• GARA uses the PKI based Grid Security
Infrastructure (GSI) for authentication and coarse authorization– Authentication uses long-term PK and short term
proxy credentials– Authorization is controlled by an ACL-based flat file
• Our contributions:– Fine-grained cross-domain authorization– PK credentials based on Kerberos identity– Secure web interface
Cross-domain Authorization• Use existing local group services
– Avoid replicating data and management tasks
• Group name-space shared by domains– Local administrators manage group membership as usual
• KeyNote Policy Engine makes authorization decision• Fine-grained authorization expressed in KeyNote
policy rules– Group membership– Amount of bandwidth allowed– Time/duration of reservation
Local Domain Authorization
• Local GARA contacts local group service to see what groups a user is a member of
• Group membership passed into KeyNote along with reservation request parameters
• KeyNote compares input parameters to rules• If authorized, the local GARA client:
– Packages and signs username and group membership
– Adds it to the reservation request that is forwarded to the remote site
Remote domain Authorization
• Remote GARA accepts and verifies the username/group membership from the wire
• Group membership is passed into KeyNote along with reservation request parameters
• KeyNote compares input parameters to the rules to make authorization decision
• If remote authorization fails, reservation at the previous node is cancelled.
Kerberos leveraged PKI: kx.509
BrowserUser
KCTWeb
Server
KCA
Sign my short-term key
SSL handshake(recorded)
SSL transcript
Service ticket
Web server as proxy GARA client
Local GARA
KeyNote
Remote GARA
KeyNote
Web Server
GARA client
Group Service
Router Pool
Router Pool
Signed group membership =>
Request group membership
AFS PTS or LDAP
Demonstration: UMICH to CERN
• Multiple security realms• AFS Protection Server (PTS) is used for the local
group service• MJPEG video conferencing application
– 10 MB/sec stream each way, 147ms round trip
– RTP headers record packet loss statistics
• Iperf traffic generated at each end across video and audio receiving router interface
• Cisco 6506 at UMICH, Cisco 7500 at CERN
Demonstration: UMICH to CERN
• Note high quality video and audio• Turn on Iperf traffic at one end to degrade video
and audio signal• Place a reservation in the near future (1 minute) for
a short duration (20 seconds)• Note degraded video and audio return to high
quality during the 20 second reservation, in spite of competing traffic generation
• Note degraded video and audio return at the end of the reservation
Cisco 6506
GARA ServiceAFS PTS
Group Service
Web ServerGARA Client
KCA
KCT/KDC
Browser
CITI.UMICH.EDU
ATLAS.UMICH.EDU
IGRID2002
GARA Service
Cisco 7206
KINIT
KX509 KX509
SSL
RX
GSI
GSI
TELNET
SSH
MJpeg Host
MJpeg Host
Reserved Video Conference
“Big Picture”
Any Questions?http://www.citi.umich.edu/projects/qos
Demonstration: UMICH to CERN
We demonstrated that a reservation failed if:– User not in correct group– Requested bandwidth out of bounds– Time of request is out of bounds
Future directions
• On going project extends the existing infrastructure to accommodate general web based network monitoring tools