In today’s computer-dominated world of business, there needs to be a continuous availability of electronic data and hence, backup and disaster recovery of electronic data is very essential. For a business to sustain success in this very competitive environment, online transactions are the main attraction for the customers and channel partners. Backup and disaster recovery thus acquires a prominent place in the successful operation of the business. This recovery process is the combined effect of all the myriad policies and activities minutely planned by any organization to ensure that there is no loss of the electronic data. Most organizations today aim to maintain a paperless office, so not much information is stored on paper and the electronic medium is utilized mainly.
The Internet becomes a more and more important part of our lives. This is a true fact for almost everybody and this is why Internet security should be a major concern for everybody too. Unfortunately, many people fail to realize the importance of Internet security and they leave things the way they are out of convenience. No matter what you use the Internet for, you should definitely try to increase the Internet security degree.
There are many malware types besides the well known viruses. There are adware, spyware and other threats you should be protected against. This is why many times only one Internet security program is not enough. Having at least an antivirus is important but it will not suffice many times in your fight against cyber criminals.
Has your php site been exploited or hacked? What can you do to make sure this does not happen again?
I recently went through these points that I judge extremely useful to keep your website safe.
- Set register_globals to OFF
- Turn off Display Error/Warning Messages. Set display_error to ZERO.
- Never run unescaped queries
- Validate all user inputs. Items on Forms, in URLs and so on
- Move config.php and files containing Passwords to MySQL to a secure directory outside of the public_html folder
- Change permissions on any configuration files containing private information such as database passwords or email accounts to 440 so they cannot be written to and so there is no world permissions. If you need to edit them at a later time you will need to change it back to 640.
- Access Control: You don’t want the user to have access to any Admin function or Clean up scripts
- The .htaccess file is your friend. Use it to deny access to your site or files. (We also have an easy IP Deny Manager tool in the cpanel)
- PHP can parse any valid script, whether it is called foo.php, very_long_name.php.php.php, or even deleteme.bat.
- Using the default extension of “.php” means that before your hackers start you have already told them you are using PHP.
- As mentioned, you can use any filename for your scripts – if you are using PHP for every script on your server, consider using the “.html” extension for your scripts and making PHP parse HTML files.
- You can change your file extension by adding this line to the .htaccess or turn it on via the Apache Handlers in the cPanel (AddHandler application/x-httpd-php5 .html)
- To protect against SQL injection attacks Sometimes hackers will try to screw up your database by inserting SQL code into your form input fields. They can for example, insert code that could delete all the data in your database!
- To protect against this, you need to use this PHP function:
- mysql_real_escape_string()
- This function escapes (makes safe) any special characters in a string (programmers call text a ‘string’) for MySQL.
- Example: $name = $_REQUEST['name']; $safe_name = mysql_real_escape_string($name); Now you know the variable $safe_name, is safe to use with your SQL code.
- Keep the PHP code to yourself. If anyone can see it they can exploit vulnerabilities.
- You should take care to store your PHP files and the necessary passwords to access your MySQL databases in protected files or folders.
- The easy way to do this is to put the database access passwords in a file with a .inc.php extension (such as config.inc.php), and then place this file in a directory which is above the server’s document root (and thus not accessible to surfers of your site).
- Then, refer to the file in your PHP code with a require_once command.
- By doing things this way, your PHP code can read the included file easily but hackers will find it almost impossible to hack your site.
You can find more information about hardening your PHP scripts at: PHPsec.org
Also, for security purposes, you can refer to these two websites:
| Top 8 Updated list | Bit Defender | Kaspersky Antivirus | Trend Micro AntiVirus | Panda Antivirus | McAfee VirusScan | AVG Anivirus Pro | Norton Antivirus | F-Prot for Windows |
This is the list of the top 20 antivirus applications tested using about 200.000 virus samples.
Rank –> Name –> Virus detected percentage
1. Kaspersky version 7.0.0.43 beta – 99.23%
2. Kaspersky version 6.0.2.614 – 99.13%
3. Active Virus Shield by AOL version 6.0.0.308 – 99.13%
4. ZoneAlarm with KAV Antivirus version 7.0.337.000 – 99.13%
5. F-Secure 2007 version 7.01.128 – 98.56%
6. BitDefender Professional version 10 – 97.70%
7. BullGuard version 7.0.0.23 – 96.59%
8. Ashampoo version 1.30 – 95.80%
9. eScan version 8.0.671.1 – 94.43%
10. Nod32 version 2.70.32 – 94.00%
11. CyberScrub version 1.0 – 93.27%
12. Avast Professional version 4.7.986 – 92.82%
13. AVG Anti-Malware version 7.5.465 – 92.14%
14. F-Prot version 6.0.6.4 – 91.35%
15. McAfee Enterprise version 8.5.0i+AntiSpyware module – 90.65%
16. Panda 2007 version 2.01.00 – 90.06%
17. Norman version 5.90.37 – 88.47%
18. ArcaVir 2007 – 88.24%
19. McAfee version 11.0.213 – 86.13%
20. Norton Professional 2007 – 86.08%
You probably didn’t casually invite, or extend a formal attendance request to, these undesirables known as viruses.
Regardless of your opinions, such cyber-nomads may call on you, complete and active, with their destructive payloads.
So what is a virus?
A virus is a program that can self replicate or reproduce itself.
by: www.SemSim.com
Cisco has defined a hierarchical model known as the hierarchical internetworking model. This model simplifies the task of building a reliable, scalable, and less expensive hierarchical internetwork because rather than focusing on packet construction, it focuses on the three functional areas, or layers, of your network:
Core layer: This layer is considered the backbone of the network and includes the high-end switches and high-speed cables such as fiber cables. This layer of the network does not route traffic at the LAN. In addition, no packet manipulation is done by devices in this layer. Rather, this layer is concerned with speed and ensures reliable delivery of packets.
Distribution layer: This layer includes LAN-based routers and layer 3 switches. This layer ensures that packets are properly routed between subnets and VLANs in your enterprise. This layer is also called the Workgroup layer.
Access layer: This layer includes hubs and switches. This layer is also called the desktop layer because it focuses on connecting client nodes, such as workstations to the network. This layer ensures that packets are delivered to end user computers.
Figure INT.2.1 displays the three layers of the Cisco hierarchical model.
When you implement these layers, each layer might comprise more than two devices or a single device might function across multiple layers.The benefits of the Cisco hierarchical model include:
High Performance: You can design high performance networks, where only certain layers are susceptible to congestion.
Efficient management & troubleshooting: Allows you to efficiently organize network management and isolate causes of network trouble.
Policy creation: You can easily create policies and specify filters and rules.
Scalability: You can grow the network easily by dividing your network into functional areas.
Behavior prediction: When planning or managing a network, the model allows you determine what will happen to the network when new stresses are placed on it.
Core Layer
The core layer is responsible for fast and reliable transportation of data across a network. The core layer is often known as the backbone or foundation network because all other layers rely upon it. Its purpose is to reduce the latency time in the delivery of packets. The factors to be considered while designing devices to be used in the core layer are:
High data transfer rate: Speed is important at the core layer. One way that core networks enable high data transfer rates is through load sharing, where traffic can travel through multiple network connections.
Low latency period: The core layer typically uses high-speed low latency circuits which only forward packets and do not enforcing policy.
High reliability: Multiple data paths ensure high network fault tolerance; if one path experiences a problem, then the device can quickly discover a new route.
At the core layer, efficiency is the key term. Fewer and faster systems create a more efficient backbone. There are various equipments available for the core layer. Examples of core layer Cisco equipment include:
Cisco switches such as 7000, 7200, 7500, and 12000 (for WAN use)
Catalyst switches such as 6000, 5000, and 4000 (for LAN use)
T-1 and E-1 lines, Frame relay connections, ATM networks, Switched Multimegabit Data Service (SMDS)
Distribution Layer
The distribution layer is responsible for routing. It also provides policy-based network connectivity, including:
Packet filtering (firewalling): Processes packets and regulates the transmission of packets based on its source and destination information to create network borders.
QoS: The router or layer 3 switches can read packets and prioritize delivery, based on policies you set.
Access Layer Aggregation Point: The layer serves the aggregation point for the desktop layer switches.
Control Broadcast and Multicast: The layer serves as the boundary for broadcast and multicast domains.
Application Gateways: The layer allows you to create protocol gateways to and from different network architectures.
The distribution layer also performs queuing and provides packet manipulation of the network traffic.
It is at this layer where you begin to exert control over network transmissions, including what comes in and what goes out of the network. You will also limit and create broadcast domains, create virtual LANs, if necessary, and conduct various management tasks, including obtaining route summaries. In a route summary, you consolidate traffic from many subnets into a core network connection. In Cisco routers, the command to obtain a routing summary is:
show ip route summary
You can practice viewing routing information using a free CCNA exam router simulator available from SemSim.com. You can also determine how routers update each other’s routing tables by choosing specific routing protocols.
Examples of Cisco-specific distribution layer equipment include 2600,4000, 4500 series routers
Access Layer
The access layer contains devices that allow workgroups and users to use the services provided by the distribution and core layers. In the access layer, you have the ability to expand or contract collision domains using a repeater, hub, or standard switch. In regards to the access layer, a switch is not a high-powered device, such as those found at the core layer.
Rather, a switch is an advanced version of a hub.
A collision domain describes a portion of an Ethernet network at layer 1 of the OSI model where any communication sent by a node can be sensed by any other node on the network. This is different from a broadcast domain which describes any part of a network at layer 2 or 3 of the OSI model where a node can broadcast to any node on the network.
At the access layer, you can:
Enable MAC address filtering: It is possible to program a switch to allow only certain systems to access the connected LANs.
Create separate collision domains: A switch can create separate collision domains for each connected node to improve performance.
Share bandwidth: You can allow the same network connection to handle all data.
Handle switch bandwidth: You can move data from one network to another to perform load balancing.
About The Author
SemSim.com provides training resources for Cisco certification exams: CCIE, CCNP, CCNA, CCDP, CCDA. It offers FREE learning resources to students such as study guides and router simulation labs. For more information visit: http://www.SemSim.com: Making Cisco cetification easy!
by: www.SemSim.com
You must understand the business requirements of the network before buying a product. Based on the requirements, you can select the appropriate Cisco products.
Today, WAN technologies most often take advantage of high-speed connections, such as T-1 and E-1. Additional WAN technologies exist, including Frame Relay, ISDN, and dial-up asynchronous connections. ISDN or dial-up is used if infrequent connection is made. If a connection is used for more than two to four hours, you should use a Frame Relay or a leased line.Based on the different services available through the service provider, you can select Cisco products that can fulfill your office requirements.
Selecting Hubs
Cisco has various hub products. You can select hubs according to the type of connection required. Higher-end hubs offer network management port and console connections, middle-end hubs offer both 10 Mbps and 100 Mbps auto-sensing connections, and the lower-end hubs offer only 10 Mbps connections. Examples of fast hub series of Cisco are Cisco Fh100, Cisco Fh200, Cisco Fh300, and Cisco Fh400. Examples of micro hub series are Cisco MH1500 and Cisco MH1528.
Selecting Routers
Routers are the most popular Cisco products. To select a router, you must first know the port density and the interface speed required based on the LAN or WAN technologies used. In addition, you must identify the capacity and performance requirements of your business. The cost of the router varies according to the features you select.
Selecting Switches
A switch can be used instead of a hub in newer networks. Most switches are configured to limit collision domains, which often provides a limited security feature because users will not be able to sniff traffic as easily as in a standard hub-based network. This feature can cause confusion when using a network sniffer to analyze traffic. It is possible, however, to analyze packets on a switched network by enabling mirroring on the switch, or by using a dedicated port that allows authorized users to view all network traffic. It is important to consider whether you need 10, 100, or 1000 Mbps for each desktop or to connect between switches. To select a switch, you must consider various issues, such as business requirements, requirements for inter-switch links and trunking, port density, and type of user interface.
Product Selection Criteria
When selecting the right products for any network environment, keep the following considerations in mind:
Will the device be used as a core device, distribution device, or access device?
Does the device provide the functions that your business requires?
Does the device have adequate number of ports and the right mix of interfaces as required by your business?
Do you have to pay a lot for installing the device or can it be easily installed?
Can the device be centrally managed from an SNMP Management station or do you have to physically access the device to manage it?
Is the migration path easy?
How well does the device handle redundancy requirements?
Do you have to change your existing infrastructure, such as cabling or existing devices, to install the new device?
You may use the Cisco website http://www.cisco.com to gather more information to select products based on your requirements.
About The Author
SemSim.com provides training resources for Cisco certification exams: CCIE, CCNP, CCNA, CCDP, CCDA. It offers FREE learning resources to students such as study guides and router simulation labs. For more information visit: http://www.SemSim.com : Making Cisco cetification easy!
by: www.SemSim.com
Unshielded Twisted Pair (UTP) is a cable that has four pairs of wires twisted inside it to eliminate electrical interference. UTP cables are connected using RJ-45 connectors that have eight connector pins. The data equipment that is used for internetworking is classified as Data Terminal Equipment (DTE e.g. router interfaces) and Data Communication Equipment (DCE e.g. A WAN connects DTEs through DCE network).
UTP cables are used in many configurations and for different purposes, to form an internetwork including:
Straight-through
Crossover
Rollover
Applications of UTP include:
Serial transmission
Integrated Service Digital Network (ISDN) connections
Console connections
Modular and fixed interfaces
These configurations and applications are discussed below.
Straight-Through Cable
A straight-through cable is the standard network cable connection and is used to connect the source and destination computers through an internetworking device. Specifically, you can use it to connect a host to a hub or switch
Crossover Cable
In a crossover cable, the standard RJ-45 cable between the source and destination computers is cross-connected. A crossover cable can be used to connect:
Two computers
Two hubs
A hub to a switch
A cable modem to a router
Two router interfaces
Rollover Cable
These Cisco proprietary cables used to connect to a router or switch console port. In a rollover cable (8 pins), RJ-45 connectors are usually present at each ends and are used to connect router and computer ports. Pin 1 on one end of cable connects to Pin 8 at the other end of the cable, similarly, Pin 2 connects Pin 7, and so on.
Serial Transmission
All WANs use serial transmission, which can pass one bit at a time over a single channel. Cisco provides a 60-pin serial connector for one end of the cable while other end of the cable may be EIA/TIA-232, V.35, EIA/TIA-449, X.21 or others;
ISDN Connections
ISDN refers to a collection of standards that define a digital architecture that can carry integrated voice and data, using the public-switched network. ISDN BRI (Basic Rate Interface) is a two 64 kbps Bearer channels (2B) plus one 16 kbps Data channel (D) service. ISDN BRI terminates at the customer premise with the U interface.
Console Connections
A console is a type of DTE through which commands are entered into the host device. Most Cisco devices support the RJ-45 console connection. A rollover cable with an RJ-45 connector is used to connect the PC or terminal to the console port of the Cisco device.
Modular and Fixed Interfaces
Unlike a fixed interface router, a modular interface router allows you to add new interface cards without buying a new router.
In the fixed interface series, you refer to the interfaces as:
interface_type interface_number
For example, the first serial interface on a Cisco 2503 router would be referred to as serial 0. Higher routers have modular interfaces that allow you to change the interfaces as and when required. Here, the interfaces are referred to as:
interface_type module_number/interface_number
To practice such commands you can download a free CCNA router simulator from SemSim.com and proceed to the troubleshooting 1 exercise that configures ethernet 0 interface.
About The Author
SemSim.com provides training resources for Cisco certification exams: CCIE, CCNP, CCNA, CCDP, CCDA. It offers FREE learning resources to students such as study guides and router simulation labs. For more information visit: http://www.SemSim.com : Making Cisco cetification easy!
by: Chris Bryant, CCIE #12933
There are plenty of articles out there about how to prepare for the CCNA exam. However, there are also things you can do to increase your chances of success on exam day during the most important part of the entire process — the time that you’re actually taking the test.
I’ve taken many a certification exam over the years, and helped many others prep for theirs. Here are the five things you must do on exam day to maximize your efforts.
1. Show up on time. Yeah, I know everyone says that. The testing center wants you there 30 minutes early. So why do so many candidates show up late, or in a rush? If you have a morning exam appointment, take the traffic into account. If it’s a part of town you don’t normally drive in during rush hour, you might be surprised at how much traffic you have to go through. Plan ahead.
2. Use paper, not the pad. Some testing centers have gotten into the habit of handing exam candidates a board that allegedly wipes clean, along with a marker that may or not be fine-pointed. You do NOT want to be writing out charts for binary math questions, or coming up with quick network diagrams, with a dull magic marker. It’s also my experience that these boards do not wipe clean well at all, but they smear quite badly.
Ask the testing center employee to give you paper and a pen instead. I haven’t had one refuse me yet. Remember, you’re the customer. It’s your $100 – $300, depending on the exam.
3. Use the headphones. Most candidates in the room with you understand that they should be quiet. Sadly, not all of them do. Smacking gum, mumbling to themselves (loud enough for you to hear, though), and other little noises can really get on your nerves in what is already a pressure situation. In one particular testing center I use, the door to the testing room has one setting: “Slam”.
Luckily, that center also has a headset hanging at every testing station. Call ahead to see if yours does. Some centers have them but don’t leave them at the testing stations. Wearing headphones during the exam is a great way to increase your powers of concentration. They allow you to block out all noise and annoyances, and do what you came to do — pass the exam.
4. Prepare for the “WHAT??” question. No matter how well-prepared you are, there’s going to be one question on any Cisco exam that just stuns you. It might be off-topic, in your opinion; it may be a question that would take 20 of your remaining 25 questions to answer; it might be a question that you don’t even know how to begin answering. I have talked with CCNA candidates who got to such a question and were obviously so thrown off that they didn’t do well on any of the remaining questions, either.
There is only one thing to do in this situation: shrug it off. Compare yourself to a major-league pitcher. If he gives up a home run, he can’t dwell on it; he’s got to face another batter. Cornerbacks in football face the same problem; if they give up a long TD pass, they can’t spend the next 20 minutes thinking about it. They have to shrug it off and be ready for the next play.
Don’t worry about getting a perfect score on the exam. Your concern is passing. If you get a question that seems ridiculous, unsolvable, or out of place, forget about it. It’s done. Move on to the next question and nail it.
5. Finish with a flourish. Ten questions from the end of your exam, take a 15-to-30 second break. You can’t walk around the testing room, but you can stand and stretch. By this point in the exam, candidates tend to be a little mentally tired. Maybe you’re still thinking about the “WHAT??” question. Don’t worry about the questions you’ve already answered — they’re done. Take a deep breath, remember why you’re there — to pass this exam — and sit back down and nail the last ten questions to the wall.
Before you know it, your passing score appears on the screen!
Now on to the CCNP ! Keep studying !
Chris Bryant
CCIE #12933
About The Author
Chris Bryant, CCIE™ #12933, has been active in the Cisco certification community for years. He worked his way up from the CCNA to the CCIE, and knows what CCNA and CCNP candidates need to know to be effective on the job and in the exam room.
He is the owner of http://www.thebryantadvantage.com, where he teaches CCNA and CCNP courses to small groups of exam candidates, ensuring they each receive the individual attention they deserve. Classes are offered over the Internet and in select cities. Chris has custom-written the Study Guide and Lab Workbook used in each course – no third-party training materials or simulators are used. You’re invited to visit our site and check out our CCNA and CCNP courses and study aids, and to sign up for our weekly newsletter written personally by Chris. Chris is always glad to hear from Cisco certification candidates at chris@thebryantadvantage.com.
by: Chris Bryant, CCIE #12933
One question I’m often asked by CCNA candidates is whether to take the “one big exam”, or take the two separate exams required by Cisco to achieve the Cisco Certified Network Associate (CCNA) exam.
The question comes up because there are now two separate paths to the CCNA certification. Candidates may take a single exam, 640-811, or two exams, 640-821 and 640-811.
What’s the difference? The two-exam approach involves exams with different topics and therefore different preparation techniques. 640-821 is the Introduction To Cisco Networking Technologies exam. This course does introduce the candidate to Frame Relay, PPP, and other WAN technologies, but goes into little detail. Emphasis in the Intro course is placed on knowing how Ethernet behaves, how different types of cable are used for different purposes, and knowing what cable to use in a certain situation. The candidate should expect some questions involving binary math as well, but they will involve fairly simple conversions.
The 640-811 exam, Interconnecting Cisco Networking Devices, goes into much more detail on WAN technologies. Routing and switching behavior are covered, and the candidate is expected to answer difficult questions involving binary math and subnetting as well. The candidate may also have to demonstrate ability to configure a router or switch via a simulator. Since the ICND exam goes into more detail, it’s generally considered the more difficult exam.
The approach I recommend to a CCNA candidate depends on their background. If the candidate is a relative newcomer to networking, or hasn’t taken a certification exam before, I recommend they take the two-exam approach. This allows the candidate to focus only on the Intro topics, and gives them a strong sense of confidence after passing the Intro exam. That confidence flows over into the ICND exam.
For those who have networking experience, and are very familiar with Ethernet behavior and cable types, I recommend the one-exam approach. This allows the candidate to focus on the more advanced topics they’ll be seeing in the single exam, while spending just a little time reviewing their Intro-level knowledge.
Regardless of the approach you choose, the path to true CCNA success remains the same. Get some real hands-on experience, either by renting rack time online or by putting together your own home lab. Understand what’s going on “beneath the command”; don’t use router commands when you don’t understand what they’re doing. Add to that a true mastery on binary math, and you’re on your way to having the magic letters “CCNA” behind your name!
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
About The Author
Chris Bryant, CCIE (TM) #12933, has been active in the Cisco certification community for years. He worked his way up from the CCNA to the CCIE, and knows what CCNA and CCNP candidates need to know to be effective on the job and in the exam room.
He is the owner of http://www.thebryantadvantage.com, where he sells his popular CCNA and CCNP study aids, including his unique Flash Card Books. He also teaches CCNA and CCNP courses to small groups of exam candidates, ensuring they each receive the individual attention they deserve. Classes are offered over the Internet and in person in select cities. Chris has custom-written the Study Guide and Lab Workbook used in each course – no third-party training materials or simulators are used. You’re invited to visit our site and check out our CCNA and CCNP Courses, Flash Card Books, and to sign up for our weekly newsletter written personally by Chris. Chris is always glad to hear from Cisco certification candidates at chris@thebryantadvantage.com.