CS 111

Scribe Note – 12/03/2009

By HoJung Hwang, Wei Wong

Mainframes – 1960s

Data-intesive

Data optimization

Reliability

Clusters 1990s

Beawulf

SGE (SUN GRID ENGINE)

IP Network

Can be heterogeneous (x86-64 is typical)

Clouds

“Clusters of Cluster”

Who controls the cloud? Security

Who pays? Resource Management

(Political Issue) (technical issues)

Amazon EC2

Globus

Cloud Advantages over clusters/grids

- Short-Term Commitment (capital investment savings)

- Pay as you go

- Can grow quickly as needed (fast scaling) – varying demand

Cloud Disadvantages

- Money ->” it all depends” – run the numbers vs. clusters

- Privacy – data confidentiality

Encrypt data to & from the cloud

- Network latency

- Data transfer bottleneck

archiving

sneakernet style technology

- Bugs (hard ones that crap up as you scale unsolved problems (if solving it cheaply)

[Conservatism is in order]

- Other security – Dos attack

Physical attack

- Overload risk

multiple suppliers

societal risk

overload of data access-often biggest problem

Scalable storage

Vendor Lock-In

Software Licensing Big Bucks problem (licensing formulas)

Free software

(Problem : you take linux run it in cloud, don’t distribute it)

- Security Again

- Simpler, easy to manage/understand

- Prohibit “bad” accesses accurately

- Allow “good” accesses accurately

Traditional Unix Origianl Unix

Ex) rwx rwx rwx User had 1 group

User group other BDS multiple groups

I can’t run CS111 on dept servers because only root can create groups

ACLs Access Control Lists

Owner of a resource can specify access list

List of principals & their accesses

$getfacl (simple ACL) $setfacl

user::rwx

group::r-x

other::r-x

ACL key idea

Make sure default ACLs are fight when a resource is created

$ Sudo

#cd /bad/gu

#ls

Role-Based Access Control (RBAC)

e.g. backup

power off

change grades

For each user: which roles can they assume?

Mechanisms for enforcing access control

- ACLs etc.. each resource has an ACL (controlled by OS) attached to it

all access mediated by OS (syscall)

- Capabilities: each principal has a “RCL” set of capabilities

Trusted Software

From an O.S. viewpoint: OS don’t trust apps because they don’t trust users and apps run on behalf of users (principals)

Setuid(10976): only root can do it

Setuid program

Which programs do we trust? =>as few and as small as possible

How can we trust login? Cryptographic checksum of program

How does vendor trust login? Login.c ->login.o

gcc.c if compling login.c then generate buggy code / if compling gcc then generate buggy code