What is meant by flow specification?

- There are many problems concerning the flow specification. 

- There are limited options for the provider for mitigation of the DDoS attacks that take place internally. 

- These can be categorized in to three different categories:

Ø  BGP (border gateway protocol) destination black holes

Ø  BGP src/ uRP

Ø  ACLS

- The basic idea is to make use of the BGP for the distribution of the flow specification filters. 

- This helps in dynamic filtering in the routers. 

- The flow specification rules are encoded according to the BGP NLRI address family. 

- The flow spec NLRI is used by the BGP as its opaque key is used as an entry key for its database. 

- The extended communities are used for specifying the actions such as accepting, discarding it, rate limiting, sampling, redirecting and so on. 

- The source/destination prefix and the source/destination port are matched in combinations according to the packet size, ICMP type/co9de, fragment encoding, DSCP, TCP flag and so on. 

- For example, the TCP ports 80…90 are matched with 192.168.0/24. 

- The flow specification trust model uni casts the routing advertisements for controlling the traffic. 

- Filter is considered as a hole for the traffic that is being transmitted to some destination. 

- Filter is accepted when it is advertised for the destination by the next hop. 

- Filters with various flow specifications are available today.

- The major benefit of the flow specifications is the filters with the fine grain specification which make it easy for deploying and managing the BGP. 

- The trust and the distribution problems are solved by the BGP. 

- ASIC filtering in routers is leveraged. 

- This is another major benefit of flow specifications. 

Apart from the benefits, there are various limitations of the flow specifications as mentioned below:

Ø  There is no update level security in the BGP.

Ø The statistics and the application level acknowledgement are not well defined.

Ø  The flow specifications work only for those nodes for which the BGP has been enabled.

Ø  Beyond routing the BGP payload has to be overloaded.

Ø  There are various operational issues between the security operations and the network operations.

Ø  The threat information cannot be gathered in one place.

- The integration of the flow specifications was announced by various security vendors. 

- The DDoS attacks are experienced by a large number of customers. 

- The DDoS attacks are now massive and have put the network infrastructure at risk apart from the end customer. 

- Congestion problems occur at both the exchange and the backbone. 

- The attacks of long durations add to the cost of bursting and circuit congestion problems. 

- Depending up on the size of the attack the POP has to be isolated.

- VoIP is also affected. 

- These attacks have negative economic effects as the cost of the operations has been increased. 

- This has led to a degradation of the business. 

- Measures such as firewall filtering and destination BGP black-holing have proved to be insufficient in preventing the attacks. 

- These methods are slow since it is required to log-in and configuring the devices. 

- The configuration has to be constantly. 

- The traffic is terminated to some destination. 

- This affects the availability. 

- The black hole routes are removed by constantly changing the configurations. - Earlier version of the flow specifications had many bugs. 

- There were some limitations on the performance. 

- However, it provided arbor support for the actions of the flow specifications. 

- It does not provide multi–vendor support. 

- To some extent it provides the mitigation facility for the attack that occurred at the source. 

- The collateral damage is eliminated for both the carriers and supports the change in the matching criteria. 

How does QTP recognize Objects in AUT?

The quick test professional comes with two types of object identification mechanisms unlike winrunner as mentioned below:

1. Usual or the normal object identification mechanism and
2. The smart identification mechanism

What is Usual or Normal Object Identification Mechanism

- In the usual object identification routine, the first step of the quick test professional is to learn the description of the object as provided by the user before the starting of the test. 

- The description of the object provided by the user consists of the properties of the object. 

- All the objects present in the software system or AUT (application under test) are matched one by one with this physical description.

- It is checked that how many properties of the object are matching with the properties mentioned in the description. 

- This method is the easiest  of the two above mentioned object identification routines. 

Now what if this usual object identification mechanism fails to identify the object? 

The alternative here is the second object identification mechanism i.e., the smart identification mechanism. 

Why does a the normal method fails?

- The normal method fails because the value of the object properties starts changing dynamically which makes it difficult for the quick test professional to track the object. 

- Another situation in which the normal identification mechanism can fail is when the quick test professional finds not one but more than one objects in the application under test matching with the properties mentioned in the description. 

- In such a case the quick test professional erases from its memory the learnt description of the object and calls up on the smart identification mechanism for the identification of that particular object. 

Let us see a comparison between the smart identification mechanism and the normal identification mechanism:

1. Smart identification is more complex then the usual one.
2. Smart identification is more flexible then the usual one.

What is Smart Identification Mechanism

- Smart identification mechanism is so reliable that it can work even if the currently provided description of the object fails.

- To get the best out of the smart identification mechanism, one needs to configure it properly in a logical way. 

- Smart identification mechanism is driven by two different sets of properties as described below:

1. Base filter properties: As the name suggests these are the base or the fundamental properties belonging to a particular test object class. The value of these fundamental properties cannot be changed until and unless you make changes in the properties of the original object.
2. Optional filter properties: The leftover properties i.e., all the properties leaving out the base filter properties are grouped under this category i.e., the optional filter properties. These properties unlike the other base filter properties do not change frequently. These properties can some times be ignored i.e., when they do not hold to be applicable and therefore have been named as optional filter properties.

How the smart identification process follows?

- The description given by the user is erased from the memory of the quick test professional and a list of objects called candidate list is created.

- Objects or candidates in this list match at least one property in the property list. 

- Now, the base filter properties are used for cutting down on the list of the object candidates. 

- The list is narrowed down to only one object which has most number of properties matching in the list of properties. 

- Some times it may happen even after reaching this stage the quick test professional may not find a matching object. 

- In such a case the quick test pro makes use of an ordinal identifier in addition with the learnt description. 

What is smart Identification in QTP?

Smart identification mechanism is one of the most important and effective mechanisms of the quick test professional. Usually for the identification of an object the quick test professional goes around the usual i.e., the normal identification process.

But what the quick test professional is supposed to do when this usual object identification routine fails? At this point the smart identification mechanism of the quick test professional comes to the rescue of the testers.

Smart Identification in QTP

- The smart identification mechanism has got many positive attributes.

- It is more flexible and works with more efficiency for the identification of the difficult objects present in the application that cannot be found with the normal identification mechanism. 

- But for the smart identification to work, it is required that you enable this option in the object identification settings. 

- Smart identification mechanism works up on two types of properties as mentioned below:

1. Base filter properties and
2. Optional filter properties.

- The first category of the properties i.e., the base filter properties constitute of the most fundamental properties pertaining to a particular class of test object. 
- The values of the properties falling in this category cannot be changed or altered without changing the same properties in the original object.
- The second category of the properties i.e., the optional filter properties consists of the other properties that contribute in the identification process of the objects. 
- In the process of smart identification of an object, the quick test professional first erases from its memory the learnt description or the description that was entered by the user in to the physical description field of the object. 
- Instead of this single object, a list of matching objects (in this case such objects are called candidates) is created by the quick test professional called the candidate list. 
- This list is created based up on the properties that have been defined in the category of base filter properties and thus all the objects match a little or lot (i.e., to say one or more properties) with the base filter properties. 
- Base filter properties as the name suggests are the major properties that help cut down or reduce the number of objects in the candidate so that an exact match can be found or we can say that the area of search is reduced. 
- The idea is to be left with only one object matching with most or all of the properties mentioned in the saved description. 
- In some cases it may happen that it may be required to invoke smart identification mechanism during the run session. 
- In such cases a warning message is generated by the test results tree which indicates about the invocation of the smart identification and insertion of a smart identification process. 
- It is said that the smart identification is applicable only for the web based applications. 
- The object is recorded from the AUT or application under testing and its properties are identified accordingly and finally the scripts are executed. 
- Some times you may receive a warning alert in the results of the tests. 
- You just need to navigate over this message in the file which stores the messages and read what it says and follow accordingly. 
- Usually the normal identification routine fails whenever there occurs a dynamic change in the properties of the object to be identified. 
- Because of such dynamic changes the value of the object properties keep on changing thus making it difficult for the quick test professional to track that particular object. 
- These dynamic changes are shown only in the result and are not stored in the local object repository and are accessible only for the run  time.