Access control and markup languages

Organizations need a way to control how their information is used internally within their applications. Extensible Markup Language (XML) is the standard that provides the meta data structures to allow this expression of data. Organizations need to be able to communicate their information, and since XML is a global standard, as long as they both follow the XML rules, they can exchange data back and forth.Users on the sender’s side need to be able to access services on the receiver’s side, which the Service Provisioning Markup Language (SPML) provides. The receiving side needs to make sure the user who is making the request is properly authenticated by the sending company before allowing access to the requested service, which is provided by the Security Assertion Markup Language (SAML). To ensure that the sending and receiving companies follow the same security rules, they must follow the same security policies, which is the functionality that the extensible Access Control Markup Language (XACML) provides.

Simple Object Access Protocol, is a protocol specification for exchanging structured information in the implementation of Web Services in computer networks. It relies on Extensible Markup Language (XML) for its message format, and usually relies on other Application Layer protocols, most notably Remote Procedure Call (RPC) and Hypertext Transfer Protocol (HTTP), for message negotiation and transmission.

This XML based protocol consists of three parts: an envelope(which defines what is in the message and how to process it),header and body.

   
 
   
 

Access control

Access control is what subject can control what objects and what type of commands and operations they can carry out.

Access control categories:

• Administrative controls (personal controls, Supervisory structure, security awareness training, testing)
• Physical controls ( Network segregation, Perimeter Security, Computer controls, work area separation, cabling, control zones)
• Technical controls (System access, network architecture, Network access, encryption and protocols, auditing)

Access control types

• Preventive - keep undesirable events form happening
• Detective - identify undesirable events that have taken place
• Corrective - correct undesirable events that have taken place
• Deterrent - Discourage security violations form taking place (we are serious about security "Beware of dogs")
• Recovery - Restore resources and capabilities after a violation or accident
• Compensation - provide alternatives to other controls (based on cost/benefit analysis)

Process of getting access in to the system

• Identification - publicly known information but shouldn't be descriptive(username, userID)
• Authentication - Something you know(password,pin),something you have(smartcard,token) and something you are(biometrics). Strong authentication is two of authentication components.
• Authorization - ACL
• Accountability

It is important to asses the your passwords by trying to crack the password your self using the tools available. Password can be cracked using dictionary attack and exhaustive attacks.Rainbow table make password cracking easier by machining hash values. As solution for this we can use one time passwords with a authentication server(challenge response authentication).

Smart cards are good method of authentication.There are two types of smart cards, contact and contact(in/out chip) less(small antenna inside). Fault generation is one of the attack against smart card. Fault generation is manipulating the something outside the card(reader) to get into the data in smart card. Then there are software attacks exploiting the software flaws inside the card. Side channel attack means we are not doing anything to the card, just watch and gather information(gathering radiation, time it took to authenticate).Micro probing is connecting to the circuits directing by peeling of the chip on the card.

Data classification and clearance

Data classification is really important in the industry. There are lot of news in security leakages due to poor data classification.In the military data classification and clearance has higher importance. In military they classify data as unclassified data, confidential data, secret data and top secret data. why we don't call all the data top secret and consider it done. If we do so we waste cost in putting unnecessary security measures and waste lot of man power in managing them. So it is really important to design data classification model appropriate to our industry.Also it is important to define the security clearance.we have to define who are the data owners, what are their responsibilities and data classification in the organization. To start we should build a security policy which outline everything that we decided upon.Then we have our procedures, guidelines and standards to define it further.

Too many classification levels are impractical and add confusion. Too few classification levels gives the perception of little value and use. And there should be no overlap between classification levels.It is very common that lot of companies have three classification levels.Also we should follow a standardize approach for our information classification criteria.

Weakest link in security is people.That's why employ management is really important when you look in at enterprise security.80% of threat are internal and 20% are external(80/20 rule).People make mistakes.Policies should enforce in recruiting people, firing people and security training.

Hiring and Firing procedures:

Pre employment

• Background check
• security clearance
• Credit check
• drug screening

Termination procedures:

• Complete an exit interview (review non-disclosure agreement)
• Individual must surrender ID, keys and company assets
• User's accounts must be disabled

Want to be a Database administrator

A personal database is typically maintained by the individual who owns it and uses it. However, corporate or enterprise-wide databases are typically important enough and complex enough that the task of designing and maintaining the database is entrusted to a professional, called the database administrator (DBA).

The DBA is responsible for many critical tasks:

• Design of the Conceptual and Physical Schemas - Based on the user's requirment, the DBA must design the conceptual schema (decide what relations to store) and the physical schema (decide how to store them).
• Security and Authorization: The DBA is responsible for ensuring that unauthorized data access is not permitted
• Data Availability and Recovery from Failures: The DBA must take steps to ensure that if the system fails, users can continue to access as much of the uncorrupted data as possible.DBA is responsible for implementing procedures to back up the data periodically and maintain logs of system activity (to facilitate recovery from a crash).
• Database Tuning: Users' needs are likely to evolve with time. The DBA is responsible for modifying the database, in particular the conceptual and physical schemas, to ensure adequate performance as requirements change.

Features of DBMS

A very important advantage of using a DBMS is that it offers data independence.Application programs are insulated from changes in the way the data is structured and stored.users can be shielded from changes in the logical structure of the data, or changes in the choice of relations to be stored. This property is called logical data independence.the conceptual schema insulates users from changes in physical storage details. This property is referred to as physical data independence.

A DBMS provides a specialized language, called the query language, in which queries can be posed.

Query languages:

• Relational calculus- based on mathematical logic, and queries in this language have an intuitive, precise meaning. 
• Relational algebra-based on a collection of operators for manipulating relations

A DBMS enables users to create, modify, and query data through a data manipulation language (DML). Thus, the query language is only one part of the DML, which also provides constructs to insert, delete, and modify data. Let's discuss the DML features of SQL in a later blog post.

An important task of a DBMS is to schedule concurrent accesses to data so that each user can safely ignore the fact that others are accessing the data concurrently.A locking protocol is a set of rules to be followed by each transaction.A lock is a mechanism used to control access to database objects.Two kinds of locks are commonly supported by a DBMS: 

• Shared locks on an object can be held by two different transactions at the same time
• Exclusive lock on an object ensures that no other transactions hold any lock on this object

A DBMS must ensure that the changes made by incomplete transactions(system interruption,crashes) are removed from the database.To do so, the DBMS maintains a log of all writes to the database.A crucial property of the log is that each write action must be recorded in the log (on disk) before the corresponding change is reflected in the database itself.This property is called Write-Ahead Log, or WAL.

Introduction to Database

What is a database? A database is a collection of structured data. A database captures an abstract representation of the domain of an application.

• Typically organized as “records” called as entities
• and relationships between records

A DBMS is a (usually complex) piece of software that sits in front of a collection of data, and mediates applications accesses to the data, guaranteeing many properties about the data and the accesses.A data model is a collection of high-level data description constructs that hide many low-level storage details. A DBMS allows a user to define the data to be stored in terms of a data model. Most database management systems today are based on the relational data model.A widely used semantic data model called the entity-relationship (ER) model allows us to pictorially denote entities and the relationships among them.

A description of data in terms of a data model is called a schema.In the relational model, the schema for a relation specifies its name, the name of each field (or attribute or column), and the type of each field.

In addition to the relational data model (which is used in numerous systems, including IBM's DB2, Informix, Oracle, Sybase, Microsoft's Access, FoxBase, Paradox, Tandem, and Teradata), other important data models include ,

• Hierarchical model (e.g., used in IBM's IMS DBMS)
• Network model (e.g., used in IDS and IDMS)
• Object-oriented model (e.g., used in Objectstore and Versant)
• Object-relational model (e.g., used in DBMS products from IBM, Informix, ObjectStore, Oracle, Versant, and others).

The database description consists of a schema at each of these three levels of abstraction:  

• Conceptual Schema : Describes the stored data in terms of the data model of the DBMS.Describes all relations that are stored in the database
• Physical Schema : specifies additional storage details.summarizes how the relations described in the conceptual schema are actually stored on secondary storage devices such as disks.
• External Schema :allows data access to be customized (and authorized) at the level of individual users or groups of users

A data definition language (DDL) is used to define the external and coneeptual schemas (SQL is a well known DDL).The process of arriving at a good physical schema is called physical database design.The process of arriving at a good conceptual schema is called conceptual database esign.

Enterprise security architecture

Layered approach : provide layers of defense that the attacker has to break before accessing an asset

Industries follow this approach and then think their system is secure. But they forget that the remote access and wireless network doesn't have enough layers in position. Security requirement can be identified as functional requirements and assurance requirements.Organization choose to be certified against the BS7799 standard to provide confidence to their customer base and partners. That is why industries make effort to comply with these standards.

Sometime numbering of the IT security standards are confusing.BS7799 security standard has two parts. After ISO took BS7799 under their wings, they introduced their own numbering.

BS7799 part 1 - ISO17799 outlines control objectives and a range of controls that can be used to meet those objectives
BS7799 part 2 - ISO27001 outlines how a security program can be setup and maintained.

COBIT defines the method of building the IT inf structure. COBIT is control objective for information related technology.this is not just about security.COBIT is a whole structure how to set up IT infrastructure. In COBIT there are four domains ;

1. Planning and Organization
2. Acquisition and implementation
3. delivery and support
4. Monitoring

In security we are just looking at the delivery and support domain.COBIT is great but it is really time consuming to implement.For security professional there are special things to learn form COBIT

• Management of IT security
• IT security plan
• Identity management
• User account management
• Security testing,surveillance and monitoring

Whole point of COBIT is keep IT alignment with business.It has performance indicators and define goals.COBIT is a very high level approach to the information security. That's how the auditors look at. They look at the control objective and check whether the control is in place.

security governance is that security is controlled by not just IT but with board members and senior management.Everybody who suppose to be involved should involve in the security.Security policy, standards, baseline, guideline and procedures have to act together to realize strong security.

Data owner is the person who responsible for protecting the data.custodian usually the IT department to the actual security setup to make sure it meet that protection level.

Risk management

Risk management is difficult because we are looking at the future. Most of the time enterprises have the question, "what is acceptable risk level". They have to comply with the regulations, look at their assets that they have to protect, asses the importance of their assets to understand their sufficient security level. How much enough security is a cost benefit balance.

(1) Planing the risk management:

• Identify Teams
• Identify Scope
• Identify Methods (Qualitative and quantitative)
• Identify tools
• Understand acceptable risk level

every company has a different risk appetite.That means how much risk they are willing to take.acceptable risk level has to be set in the enterprise. business derives are going to help define the acceptable risk level and the management has to set the level. Team is just bring the information to the management.But this is very abstract. Then we define security policies. Security policies should reflect the acceptable risk level in the system.

(2) Collect Information:

• Identify Assets
• Assign value to assets
• Identify vulnerability and threats
• Calculate risks
• Cost/benefit analysis
• Uncertainty analysis

Collecting information is a time consuming process.it is really important to identify the assets that are to be protected.There are tangible(hardware) and intangible(data, reputation) assets. Intangible assets are harder to protect. how to assign a value to an assets?Have to determine the cost, adversary, reliability and criticallily.We have to consider if something happen to a specific asset what will cost to the company in near term and long term.
We have to determine the type of analysis we are going to carried out. whether it is qualitative or quantitative is depends on the requirement of the company. managers like to see quantitative analysis. Quantitative has do with monetary values and qualitative is opinion based.

Qualitative analysis is commonly used in the industry.Experts will rate the level of risk.If we defines levels according to the probability of occurrence vs consequences of occurrence, there are levels like minor risks,high incidence risks, contingency risks and significant risks. we have to address the significant risk first and then the rest.

Single Loss expectancy (SLE) = Asset value x exposure factor

Exposure factor is the percentage of the damage that we think take place if the vulnerability is exploited. We look at one asset and one threat, then we calculate the cost impact of this on the company.

Probability of something to take place, we call it Annual rate of occurrence (ARO). ARO is number of expected incidents annually. ARO is annual metric. once year means ARM is 1.0.

Annual loss expectancy (ALE) = SLE x ARO

ALE is the potential loos that company can be gone through.This is how we determine which risk we correct first. This help us to categorize the treats and define the road map and budget allocation.

Purely quantitative analysis can't take place, but purely qualitative analysis can. We can be exact on the values that will happen in the future. That is why most of the industries choose qualitative analysis over quantitative analysis.

Losses can be potential or delayed.We have to look at what are the potential losses and what the delayed loses. Potential means what will happen quickly.Incident of a virus attack, the potential loss will be the inaccessibility of server. And the delayed loss will be loss of reputation.

cost/benefit calculation for countermeasure system also depends on lot of variables.It depends on variables like cost, maintenance fee, impact on productivity and number of man powers.

Value of countermeasure = (ALE before we put the counter measure) - (ALE after putting the countermeasure) - Annual cost of the countermeasure

If this value is negative it means implementing the countermeasure is not cost beneficial.Not just cost, there are whole list of things that we have to look at in a countermeasure. Does it fall in to least privilege, is it flexible, does it provide uniform protection, is it modular in nature,does it require human intervention, does is provide auditing functionality,does it been tested and can it be tested. when when people are involved that is where mistakes are taken place.

Disadvantages of quantitative analysis are it requires large amount of preliminary work, formulas are complex and inflexible and there are no real standards on how to carry this out.In qualitative approach assigning rating values are simple, allow for flexibility in processes and reporting results and it requires less preliminary work. Disadvantages of qualitative analysis are it is subjective, it is opinion and hard to map in to the budget. But this the most used in the industry.

Following formulas are conceptual formulas and you can not put values in to those.

Total risk = Threats x vulnerability x asset value

Total risk is when we didn't put any countermeasures in place. If we act upon the vulnerability that is the residual risk.Residual risk shows that countermeasure reduced the risk but not get rid of all the threats.

Residual risk = Threats x vulnerability x asset value x control gap
(control gap = what the control can not protect against)

Total risk - Controls = Residual risk

When we showed the results of the analysis they need some confidence on the information that used for the analysis. uncertainty analysis assign the amount of trust on the information that we are using.

Management is liable to take action on the risks.Four ways to dealing with risks: mitigation, transfer, acceptance and avoidance.Management need to know what to do with the information they collected.

(3) Management's responses to identified risks:

• Risk mitigation - implement countermeasures
• Risk transfer - Third-party involvement like purchasing cyber insurance
• Risk acceptance - Informed decision, no action taken when it is not cost beneficial
• Risk avoidance - decide to stop activity

Risk acceptance:

• cost decision
• pain decision
• visibility decision

RISK MANAGEMENT

PLAN -> COLLECT INFORMATION -> DEFINE RECOMMENDATIONS

Due diligence and due care on secure systems

Standards are best practices and it is better to follow open standards to build secure systems. In interconnected systems everybody depends on others. Following open standards make the interconnection easier and leverage interoperability. Introducing propriety security systems is not the best practice. When building a secure system we should consider following control categories. 

• Administrator controls (Defining policies, Awareness training, Risk management)
• Technical controls (Routers, IDS, Encryption, Auditing)
• Physical controls (locks, security guards)

All of these categories have to work together to achieve holistic security.But in the real enterprises there are gaps between technical people and managers. Technical people complain that top management don't listen to their requests. And the managers says that they only hear the request of more money. These gaps creates vulnerabilities in the system. Technical people have to understand to make a business case according to the business drives.

Companies consider only the technology when they building security programs. They should consider technology, business process and people using them. Security people have to understand the regulations and legal requirements (Federal laws, State laws).When laws come in to agencies (regulatory bodies) they define regulations. Also security people have to understand the business drivers and the level of risk.

Due diligence and due care is important in building security systems.Due  diligence is accessing the vulnerabilities in the system and the due care is do something about it and fix the problem. Due diligence is uncovering potential dangers, carrying assessments, perform analysis on assessment data, implement risk management and researching and understanding the vulnerabilities, threats and risks.If you brought in to court because of an attack on the your enterprise security system, due diligence is your protector.

Regulation enforce industries to comply with the security. Regulations are important to prevent corruption. USA took a serious look on regulation  after the ENRON downfall.

Why Power needs montoring

Power can not store like water and gas. So power has to generate according to the demand. Power generation sense the load demand by falling frequency. We can not always direct power in a specific path, because current always follows the path of least resistance. This means power transmission and distribution has to be monitor and control through out the day. Smart grid is the solution for the most of the problem in the power control and motoring. From power generation to the power consumption transformers steps voltage up and down to efficiently deliver power to the customer. Mainly electric grid consist of power genration, power transmission and power distribution. Substations transforms voltage from high to low or reverse. Electrical power may flow through several substations form power generation plant to the consumer.

Network security for Substation automation systems

Power system reliability has achieved higher priority in equipment implementation in the power industry over the years. Power industry has paid more attention on the information structure that supports the monitoring and controlling the power system after the August 14, 2003 black out. Initial power equipment problem in 2003 blackout, on-going and cascading failures were due to problems in providing right information to the right place within the right time.

Communication protocols are one of the most critical parts of power system operations, responsible for communication between equipment and controlling them. Theses protocols rarely incorporated any security measures since these protocols were very specialized. “Security by Obscurity” has been the primary approach because only operators are allowed to control breakers from highly protected control center. With the increasing electricity market force security by obscurity is no longer a valid concept. Because the electricity market is pressuring market participants to gain any edge they can, it is all about winning bids and loosing bids. Also the older communications protocols are being replaced by standardized, well-documented protocols that are more susceptible to hackers and other security breaches.  Since power systems failure has greater scope and cost, it is obvious that the security in the power system is crucial factor.

Now there are two infrastructures to be managed in the power systems, one is power system infrastructure and the other is information infrastructure. With saying that we can see any unreliability in the information infrastructure can cause the power system unreliable. So the information system has to ensure its reliability level to provide the required reliability level in the power system.

The International Electrotechnical Commission (IEC) Technical Council (TC) 57 Power Systems Management and Associated Information Exchange is responsible for developing international standards for power system data communications protocols. IEC TC57 has developed three widely accepted protocols, and has been the source for the IEC 61850. Those three protocols are IEC 60870-5, DNP 3.0 and IEC 60870-6.

IEC 61850 protocol security

IEC61850 is an Ethernet (IEEE 802.3) based communication protocol used for control and automation of electric substations using microprocessor based Intelligent Electronic Devices (IED’s). It was developed jointly by the IEC (International Electrotechnical Commission) and the IEEE with the aim of providing a flexible and interpretable communication system which could be easily integrated into the infrastructure of existing substations.

IEC61850 is a protocol used for control and automation of substations. In substation automated by IEC 61850, the IED’s communicate via this protocol. An IED could be any measuring instrument which has a microprocessor such as a current transformer or voltage transformer or a protection device such as a relay. They are communicating peer to peer, broadcast messages and as client server. For an example if the current transformer detect over current in the line it broadcast the value to protective devices to act accordingly.

IED network within a substation contain two main busses. 

They are namely process bus and the station bus.

• Process Bus -Transfers unprocessed power system information to the processing IED’s
• Station Bus - integrates all process buses together and provides the interface to external networks. Human Machine Interfaces (HMI) are connected to the station bus.

IEC61850 has been designed considering the security aspects of the communication. The existing security mechanisms of IEC61850 are mentioned in IEC62351-4 and IEC62351-6.

These include:

• IEC62351-4 specifies the ciphers used by IEC61850 for encryption. In addition, IEC62351-6 specifies the use of Transport Layer Security (TLS).
• Security for IEC61850 profiles using VLAN’s. Partitioning of the network into VLAN’s prevent unauthorized access of IED’s outside the designated VLAN.
• Security for Simple Network Time Protocol (SNTP) via the mandatory use of the authentication algorithms of RFC2030. This prevents tampering via false time stamp packets.
• Explicit countering of man-in-the-middle attacks and tampering using the Message Authentication Code (MAC) of IEC62351-6.
• Explicit countering of replay attacks via the specialized processing state machines mentioned in IEC62351-4.

IEC 62351 - Data and communication security

IEC has published a standard for data and communication security in power systems as IEC 62351, wich includes parts 1 to 7.

·         IEC 62351-1: Data and Communication Security – Introduction

·         IEC 62351-2: Data and Communication Security – Glossary of Terms

·         IEC 62351-3: Data and Communication Security – Profiles Including TCP/IP

·         IEC 62351-4: Data and Communication Security – Profiles Including MMS

·         IEC 62351-5: Data and Communication Security – Security for IEC 60870-5 and Derivatives (i.e. DNP 3.0)

·         IEC 62351-6: Data and Communication Security – Security for IEC 61850 Profiles

·         IEC 62351-7: Data and Communication Security – Security Through Network and System Management

IEC 61850 profiles that run over TCP/IP will use IEC 62351-3, in which the primary security measures are IPSec and TLS. It specifies the use of Transport layer security (TLS) which is commonly used over the Internet for secure interactions, covering authentication, confidentiality, and integrity. IEC 62351-4 provides security for profiles that include the Manufacturing Message Specification (MMS) with TLS.

IEC 61850 also contains three protocols (GOOSE, GSE, and SMV) that are multicast datagrams and not routable, designed to run on a substation LAN or other non-routed network. The main protocol, GOOSE, is designed for protective relaying where the messages need to be transmitted within 4 milliseconds peer-to-peer between intelligent controllers. Encryption or other security measure which will affect the transmission rate is not acceptable here. So authentication is the only security measure acceptable and IEC 62351-6 provides mechanism where theses profiles can digitally sign the messages.

IEC 62351 Part 5 relates to the specialties of serial communication. Here, additional security measures are defined to especially protect the integrity of the connections. This part also specifies the key management necessary for the security measures. IEC 62351 Part 7 describes security related data objects for end-to-end network and system management (NSM) and also security problem detection. These data objects support the secure control of dedicated parts of the energy automation network. IEC 62351 Part 8 addresses the integration of role-based access control mechanisms into the whole domain of power systems.

Security in power system operation

Security requirements of power systems are different from the other industries. As an instance internet environment is vastly different form the power system environment. So it is critical to have a better understanding of the security requirements and the potential impact of the security measures on the communication requirements of the power system operations.

Security services have been developed for industries that do not have strict performance and high reliability requirements as power industries do.

• Denial of service has far more impact in the power industry than many typical internet transactions. Preventing authorized dispatcher form accessing the power system substation control has serious consequences than preventing a customer form accessing his bank account.
• Communication channels used in power system are narrow band which permitting the overhead needed for encryption and key exchange.
• In power system industries some substations and equipments are located in unmanned remote areas which makes lot of security measures are difficult to implementation
• Wireless communication are becoming used for many applications but have to be more careful in implementing in power system because the noisy electrical environment in the power substations.

 Power system security uses large variety of communication methods and performance characteristics, single security measure cannot counter all the security threats.  For instance VPNs only secure the transport level protocols, so we need additional security measures to protect the application level protocols.  In power system communication authentication plays a larger role in many security measures, because authentication of control actions is far more important than the data through encryption. Security truly is an “end-to-end” requirement to ensure authenticated access to sensitive power system equipment, reliable and timely information on equipment functioning and failures, backup of critical systems, and audit capabilities that permit reconstruction of crucial events.

GOOSE/SMV protection

GOOSE is stand for Generic Object Orientated System-wide Events. By using GOOSE with station bus communication, aims to replace the conventional hardwired logic necessary for intra-relay coordination. When IED detect an event it multicast values to notify devices which have registered to receive the data. Because this information is time critical, performance requirements are stringent. In the GOOSE communication no more than 4ms is allowed to elapse from the time an event occur to the time of message transmission.   In order to replace the conventional method of using contacts and wires, the performance of the GOOSE messaging, i.e. transfer time should be less than 3ms for a Trip GOOSE command and 20ms for a Block GOOSE command as specified in IEC 61850-5 'Communication requirements for functions and device models’. The amount of data that would be generated after the event is based on the network topology IEDs follow, number of IEDs in the network and the type of the event. We can see that in this scenario collision are quite possible, so the GOOSE messages are retransmitted multiple times by each IED.  GOOSE model groups data value in to data sets to be published. In peer to peer data value publishing GOOSE model has several attributes that can be used to control the publishing process.

GOOSE messaging is a very important in multi vendor interoperability. The purpose and the advantages of GOOSE:

• Only a single LAN cable/fibre is required instead of connecting conventional metallic wiring between protection devices or between protection devices and primary equipment. This reduces the total cost involve in building a system in substation.
• Multi vendor interoperability, Connection between IEDs provided by different vendors is much easier to achieve
• Modification or addition of data communications between IEDs can be easily achieved by the re-configuration of the IEDs’ GOOSE settings, rather than by complex metallic wiring.

Virtual LAN vulnerabilities

In the power industry they use VLAN for layer2 security. Virtual LAN (VLAN) technology is used to create logically separate LANs on the same physical switch. Each port of the switch is assigned to a VLAN.

VLAN is not secure enough for GOOSE and SMV messages. VLAN has security vulnerabilities and only VLAN implementation is not enough for GOOSE/SMV communication. VLAN switch implementations have been susceptible to a variety of Denial of Service attacks, including traffic flooding, MAC flooding and CAM table poisoning (CAM refers to the Content Addressable Memory used to list MAC addresses reachable through each switch port).

VLAN switch configurations and deployments have been vulnerable to a number of spoofing and man-in-the-middle attacks. The most well known exploits include the following. (Links at the end of this article lead to detailed descriptions.)

• MAC address spoofing
• VLAN tag spoofing (where the attack computer falsely identifies itself as a member of a VLAN by spoofing the IEEE 802.1q tag )
• ARP cache poisoning
• Connection hijacking following a successful ARP attack
•  Multicast Brute Force Attack
•  Random Frame Stress Attack
•  Private VLAN Attack

Power industry has paid more attention on the information structure that supports the monitoring and controlling the power system. Communication protocols are one of the most critical parts of power system operations, responsible for communication between equipment and controlling them. IEC61850 protocol which is used for control and automation of substations has been designed considering the security aspects of the communication. The existing security mechanisms of IEC61850 are mentioned in IEC62351 standard. Security requirements of power systems are different from the other industries. . In order to maintain security in power systems, constant vigilance and monitoring are needed as well as adaptation to changes in the overall power system. The main purpose of the security protection is to detect the attack and eliminate it form the system. Power system security uses large variety of communication methods and performance characteristics, single security measure cannot counter all the security threats.  In IEC 61850 there are mainly five message types used for communication sample measured values, GOOSE, MMS, GSSE and time sync. There are four types of information exchange methods. They are Client/server services, GOOSE/GSE Management Services, GSSE Services and Time Sync exchange. IEC 61850 profiles that run over TCP/IP will use security measures IPSec and Transport layer security (TLS).Client server and the GSSE information exchange which uses MMS are using network layer and transport layer security measures to achieve secure combination. With stringent performance requirement in GOOSE and SMV message communication, encryption or other security measures which may significantly affect transmission rates are not acceptable. Therefore, authentication is the primary security measure for GOOSE and SMV. VLAN has security vulnerabilities and VLAN implementation alone is not enough for GOOSE/SMV communication. We should research on the better authentication which matches to the substation communication requirements and we can implement that authentication value as an extension to the GOOSE message.

Performance analysis of IPSec

With the development of web services, more social networks and commercial networks are introduced in to the internet. These internet applications deal with various types of data. Securing data over networks is becoming a more critical issue on the internet. Network security should provide confidentiality, integrity and authenticity to data networks. Network layer security protection is essential to the internet communication. The IP Security (IPSec) protocol is the most famous, secure and widely deployed security protocol that secures the data communication on the internet at the network layer. The performance evaluation of IPSec is an important factor in network security.  It is important to achieve network security without degrading the performance level in the communication system. In this paper, we analyze the IPSec performance as a network security gateway security protocol.

IPSec security protocol acts in the network layer. And it has two modes of operation: Transport mode and Tunnel mode. There are two major protocols in the IPSec protocol suite: the Authentication Header (AH) protocol and the Encapsulating Security Payload (ESP) protocol. ESP provides confidentiality, Integrity and authenticity for the communication. AH ensures authenticity and integrity of the data protected. IPSec consults Security Policy Database (SPD) and Security Association Database (SAD) to determine the way to security the IP packets. The security policy determines the security services offered to the IP flow.  The Security Associations (SAs) act as the contract between two communicating entities. They determine the IPSec protocol used in the transforms, the keys, and the duration that the keys are valid. The Internet Key Exchange (IKE) creates SAs dynamically on behalf of IPSec and manages the SAD. IKE provides key management schemes for communicating entities. Establishing IPSec connection requires two phases. Phase 1 performs mutual authentication and produces the encryption key required to protect Phase 2 transactions. Phase 2 negotiates the cipher and authentication algorithm to protect future communication.

Security is a critical factor to the development of the internet. IPSec is a suite of protocols that provides source authentication, data integrity and data confidentiality at the network layer, in both the Ipv4 and Ipv6 environments. Linux kernel 2.6 is a powerful platform for the development of security gateway. We have analyzed the performance of the security gateway in different configurations of ESP tunneling. 

When the compression is applied, we can see a drop in IPSec performance. This performance decrease happens due to the relation between the encryption algorithm speed and the compression algorithm speed. When we apply the compression to the higher speed encryption algorithm in IPSec, it will cause the throughput to degrade.  HMAC-MD5 shows a higher performance than the HMAC-S HA1 in both with compression and without. Also AES performs better than the other encryption mechanism. DES and 3DES have lower throughput than others, because of their time consuming encryption process.

The increase and decrease of throughput is based on a combination of elements: the residing layer, the header size and the relevant speed between the compression, the encryption and the transfer. AES presents better encryption capability than DES and 3DES. HMAC-MD5 has better authentication compatibility than HMAC-SHA1. We can achieve higher network security and lower performance degradation by implementing ESP tunnel with AES encryption and HMAC-MD5 authentication.

Binary data modulation with coding

When we design a communication system, we need to consider transmitter and receiver structures, probability of error, bandwidth occupancy of the modulated signal and bandwidth efficiency. Communication performance is critical factor in achieving error free transmission.


Let’s discuss the main blocks in a communication system and the way to organize them to achieve higher performance. Data to be sent is generated in the data source and fed in to the channel encoder. The purpose of the channel encoder is introducing redundancy bits to combat the effects of noise and interference over the channel. Channel coding is referred as a signal transformation designed to improve communication performance. Convolution coding is a type of channel coding. The importance characteristic of convolution coding is that coder has memory. K is a parameter called constraint length in the convolution coder. The output n-tuple emitted by coder is not only a function of input k-tuple, but also it is a function of the previous K-1 input k-tuple. 


The output of the channel encoder fed in to the digital modulator. The primary purpose of the digital modulator is to map the binary information sequence into signals suitable for transmission over the channel. We have to test Coherent phase shift keying (PSK) and Coherent frequency shift keying (FSK) modulation techniques in our communication system. Coherent receiver means receiver has a phase recovery circuitry. Receiver knows both the frequency and the phase of the carrier signal used in the transmission. PSK means signals carries information in the phase, and FSK means signal carries information in the frequency.


Modulated signal is transmitted via communication channel. Communication channel is the physical channel we use to transmit data for transmitter to the receiver. The essential feature in this physical medium is the transmitted signals are corrupted in a random manner due to various mechanisms. Here we have used Additive White Gaussian Noise channel for our simulations. Modulated signal transmitted over the channel and then converted back to sequence of binary data in the demodulator. Chanel decoder attempts to decode the channel encoded sequence. As the channel decoder in the receiver we can use maximum likelihood decoding and Viterbi decoding. We used Viterbi decoding for our simulations. The signal at the channel decoder in our scenario is the approximation of the original data.


We need to consider probability of error, bandwidth occupancy of the modulated signal and bandwidth efficiency of the communication system in designing. With coding we can achieve lower probability of error without increasing the signal to noise ratio. By introducing channel coding to the modulation, we raised the performance of the communication system. But when we used coding we need higher bandwidth for data transmission. Bandwidth the price we have to pay for the higher performance with channel coding.


We can achieve lower bit error probability in using BPSK modulation over BFSK modulation. BPSK showed higher performance than BFSK for same signal to noise ratio.With coding we can increase the performance of the communication system. When we use channel coding we can achieve the same probability of error level that we have in modulation with lower signal to noise ratio. We saw that code rate ½ perform well over code rate 1/3 at lower probability of error levels. But there is a price that we have to pay when we use channel coding in communication systems. When we use channel coding we need higher bandwidth, because we transmit more bits in the same bit duration. So higher code rates will result higher spectral occupancy. Normally, BPSK has less spectral occupancy than BFSK. 


BPSK is the best modulation technique for binary data transmission. BPSK with channel coding raised the performance level of the communication system, resulting higher utilization of the bandwidth.