2 evolution of scada

8/8/2019 2 Evolution of Scada

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Enbridge SCADA

Terminals

Transition from locally controlled on-site system to remote controlArcom Director RTU

MainlineRemote ControlledMicroVAX RTU


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The RTU Replacement Project


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LiveWIRE Design Issues

1. Achieving determinism using non-

deterministic networks2. Securing SCADA communications3. Maintaining connectivity in the face of network failures


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1. Determinism

Why SCADA data is special

No steering now, is much better thanperfect steering at some random futuremoment.Reliable failure


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Determinism - without a doubt

Operator needs a clear picture of the remote

process During absence of information - what

probably happened?


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Determinism - without delay

TCP/IP inserts arbitrary buffering, retries,

and delays Ever been unsure of whether a web siteis responding?


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Determinism - Best Effort

IP networks can be deterministic:

VOIP (Voice Over IP), RTP (Real TimeProtocol)Unfortunately, we couldnt find apackaged solution ...


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Determinism - LiveWIRE

UDP packet ageing

stale windowBlock vs Stream Communication

efficient compression and encryption blocksGuaranteed Order vs Guaranteed Delivery

delivered in order, or not at all


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2. Security

Networks allow higher level attacks

Firewalls - Avoid the Fortress mentalityAvoid software monoculturePrepare every node as if it is on the openInternet


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Security - Authentication

Key exchange and session management

sshPublic key encryptionShared key encryption

AuthenticationReplay AttacksData Integrity


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Security - LiveWIRE

Bandwidth Efficiency

Forward Error CorrectionEncoding for CorruptionInterleaving for Loss


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Discard RS parity symbolsand Decrypt Message

A2eRg#g78

Message to send (& sequence )

AHello, World!Encrypted Message (Rijndael)

A*4Gh&3aq

Compressed (Zlib)

A2eRg#g78

Reed-Solomon Encoded

A*4Gh Z@&3aq R1

Interleaved &Packetized

A1 *&4A2 3Ga

A3 hq Z

A4 R@1

A5 * ZaA6 4 @q

Extras

A7 G&R

A8 h3 1

A9 *h @

Encrypt Headers(Rijndael) andTransmit

^7 *&4

(T 3GaUu hq Z

7@R@1

8* * Za

Tw 4 @q

HeadersDecrypted

A3 hq ZA2 3 Xa

A1 *&4

?? 4 @qA5 * Za

Packets De-interleaved

A*4 Xh Z_ &3a_ R1

RS Error Correction; Extrapackets requested!

A*4 Xh Z_ &3aq R1

Extra packets received

A*4 Xh Z@&3aq R1

RS Decoding succeeds

A*4Gh Z@&3aq R1 Uncompress original message

AHello, World!

Lose, corrupt,and reorder intransit

Uu hq Z(T 3 Xa

^7 *&4

Tq 4 @q8* * Za

7@R@1

Forward Error Correction


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3. Connectivity

One-to-One

TCP/IPOne-to-Many

UDP/IP multicast


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Connectivity - LiveWIRE

Connectionless Multicast

Peer-to-Peer LiveWIRE ApplicationsDynamic RoutingRedundancy


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Scan Task

Scan Task

Procys Backups (Site 2)

Procys Primaries (Site 1)

Scan Task

Scan Task

Router

Router

Router

Frame Relay

Director

Router

Router

Command transmitted viaprimary route

Router

Router

Gig. Ethernet

ALARM()?

Dialer

Dialer

LiveWIRE Command


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Scan Task

Scan Task



Scan Task

Scan Task

Router

Router

Router

Frame Relay

Director

Router

Router

Router

Router

Gig. Ethernet

Dialer

Dialer

ALARM()OK

Command is retransmitted, andmulticast RBE data repeated,

only in case of Procys databasedetecting missing command

status!

Command transmitted viaprimary route

Router

LiveWIRE Reply


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Scan Task

Scan Task



Scan Task

Scan Task

Router

Router

Router

Frame Relay

Director

Router

Router

Router

Router

Gig. Ethernet

ALARM()?

Dialer

Dialer

Command transmitted viaprimary route is lost!

Command via WAN Route Lost


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Scan Task

Scan Task



Scan Task

Scan Task

Router

Router

Router

Frame Relay

Director

Router

Router

Router

Router

Gig. Ethernet

ALARM()?

Dialer

Dialer

After extra packets also lost,Dialup route activated, too

Command via Dialup Route


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Scan Task

Scan Task


Scan Task

Scan Task

Router

Router

Router

Frame Relay

Director

Router

Router

Router

Gig. Ethernet

ALARM()

Dialer

Dialer

After extra packets also lost,Dialup route activated, too

Commands and RBE data sentvia WAN and Dialup routes, until

Procys database alarmsautomatically detect when

outage ends.

Router

OK

RBE via Multiple Routes


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Conclusions

A modular foundation is a key element of

developing a SCADA system that is capableof evolving.It is evident after implementing theLiveWIRE project that securityenhancements will continue to play a majorrole in defining the future direction of allSCADA systems.


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Questions ?

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