Continue reading »]]> Hash Algorithms

Secure Hash Algorithm (SHA) can be defined as a set of cryptographic hash functions that were created by the National Security Agency (NSA). They were then published by the National Institute of Standards and Technology (NIST) as a United States Federal Information Processing Standard. There are three differently structured SHA algorithms which are labeled SHA-0, SHA-1 and SHA-2.

SHA-2 has a set of algorithms in itself distinguished as SHA-224, SHA-256, SHA-384 and SHA-512. The difference between SHA-0 through SHA-512 is the length of the message digest and the hash functions that are used. Each SHA algorithm uses a different number of bits. The SHA-1 is 160 bits, SHA-256 is 256 bits, SHA-384 is 384 bits and so on. SHA-512 is the most secure out of these algorithms because it uses the highest number of bits.

Another type of algorithm is called Message-Digest algorithm 5 (MD5). MD5 has now been cast aside for SHA due to flaws that were found in the design. The main difference between MD5 and SHA is that although MD5 is somewhat faster than SHA, SHA is more secure. The reason for this is because MD5 uses a 128-bit 16-byte digest while SHA uses a 160-bit 20-byte digest.

One way to reverse a hashed password is using something called a rainbow table. A rainbow table can be looked at as a code book for hash functions. It’s created by gathering every possible plain text password (within reason) that fit certain requirements (for example password length and case sensitivity).

The RainbowCrack Project is a time-memory tradeoff hash cracker. This cracker uses these same exact rainbow tables to crack hashes. The brute force hash cracker creates all possible plain text passwords and works out all of the matching hashes at the same time while also comparing it to the target.

All about IDS Evasion Methods & VPN

An Intrusion Detection System (IDS) is a setup of hardware and/or software that was designed to detect unwanted behavior such as attempts to access, immobilize or manipulate a computer system. Behavior like this will come from things such as crackers, disgruntled employees or malware. An IDS system attempts to protect against network attacks, software attacks, unauthorized access to the system, malware and more. Intrusion Detection System evasions techniques are changes that are made to an attack so that it will not be detected by an Intrusion Detection System.

I’m going to describe four different evasion techniques that will avoid an intrusion from being detected. The first one I’m going to describe is known as obfuscating attack payload. In this IDS evasion attack the “attack payload” is obfuscated or encoded so that the intended machine will reverse but the IDS will not. When security wasn’t quite as advanced as it is now, it was possible to encode the attack packet so that the IDS wouldn’t recognize it, allowing it to get to the IIS server which would decode it and then become attacked. This exploit has now been found and sealed up.

Another IDS evasion attack is fragmentation and small packets. How this works is, the attacker splits the packets into multiple segments so that it doesn’t appear as an attack until it is reassembled. The IDS receives, reassembles and then becomes victim to these packets. There are many tools out there which will allow you to split up packets, but due to security reasons these will not be revealed. Splitting packets is done by fragmenting them but packets can also be originally created split up for exactly this reason.

The third IDS evasion technique I’m going to talk about is overlapping fragments. What happens here is a series of packets are created with TCP sequence numbers set to overlap each other. An example of this is having 2 packets, one of them 70 bytes of the attack payload but the other one’s sequence number will be 66 bytes after the start of the first packet. The victim computer then rebuilds the TCP stream and tries to figure out how to deal with the four overlapping bytes. Some machines will take the new data; some will take the older data.

The last technique I will talk about is a resource exhaustion attack. This attack is also known as a DoS attack or denial of service. This attack is done by exhausting or immobilizing the IDS. With this attack you’ll use a bug found in the IDS to use up the computers resources or hide the actual attack by creating a large amount of alerts on the system. IDS alerts can be triggered by sending attack signatures through the network.

The second subject I wanted to get into was VPN and OpenVPN. VPN stands for Virtual Private network. A Virtual Private Network is a network that uses the public infrastructure already set up for things like telecommunications and internet but maintains privacy and security with the use of a tunneling protocol and various other security procedures such as firewalls. A VPN sets up a private or secure network within a public network such as the Internet.

OpenVPN is free VPN related software for creating encrypted tunnels between host computers. This can be done by creating either point to point or server to multiple client connections. OpenVPN can create direct links between systems that are protected by NAT firewalls without even having to reconfigure it.

Continue reading »]]> HANDS DOWN THE BEST TECHNICIANS IN MIDDLETOWN, WE ARE COMPUTER REPAIR!
HTTP://WWW.DOCTORPCREPAIR.COM (HTTP://WWW.DOCTORPCREPAIR.COM).

We service ALL of New Jersey though, and all of the U.S. remotely, but if you’re lucky enough to be local, you can drop your machine off or we can pick it up Not much of a need though anymore, that’s whats so great about online computer repair. Online computer repair allows us to fix your machine without you having to unplug it and drag it out of the house. It also avoids you having to get someone to stop by within your busy schedule. You can get your repaired remotely, AT YOUR CONVENIENCE. Online PC Repair is going to take over for these reasons alone!

On top of all that though, you can watch the geek as he fixes your computer! There’s no more worrying about what he or she may be doing on your machine. No more worrying about tax documents or private data stored on the machine because there’s no time for a computer support tech to snoop around! There’s also so many cases in which a PC support tech causes further damage to drum up some more money for this business call. No more of that. How could a tech do this with you watching his every click?

REMOTE COMPUTER REPAIR IS HERE AND HERE TO STAY. IT’S NOT LONG BEFORE ALL OF YOUR LOCAL BUSINESSES HAVE TO START OFFERING THE SAME SERVICE JUST TO KEEP UP, BUT STICK WITH THE GUYS WHO ALREADY ARE FAMILIAR WITH THIS TECHNOLOGY AND HAVE ALREADY PUT THEIR TIME INTO PROVIDING THIS FOR YOUR CONVENIENCE. NEED A COMPUTER SUPPORT TECH TO LOOK AT YOUR MACHINE? DONT HESITATE, GET YOUR COMPUTER REPAIRED TODAY!

HTTP://WWW.DRPCREPAIR.COM

HTTP://WWW.DOCTORPCREPAIR.COM

Click here for the Online Computer Repair Experts!

Continue reading »]]> Intermediate Routing
1. Qualified-next-hop allows unique pref. values for static routes to the same dest.
2. The default next-hop for aggregate and generated routes is 130.
3. The purpose for the Martian address list is for hosts or network addresses to be ignored.
4. Common uses for routing instances are: creating routing tables (used for filter-based forwarding), VPN services, and system virtualization.

1. The default load balancing behavior when equal cost paths exist is choosing one of the paths over which traffic for the received destination prefixes will be sent
2. Load-balance per packet policy action works by traffic spreading across the active equal cost paths randomly, while the forwarding table performs the load distribution. Each packet that matches a destination route is forwarded across a different outbound interface in a round robin fashion.
3. The instance type that FBF uses is that of inet.0.
4. The purpose of the RIB group when configuring FBF is to resolving the routes installed in the routing instances to directly connected next-hops on that interface.

1. The purpose of OSPF LSAs is to create a complete database of the network.
2. The benefits iof segmenting a large single-area OSPF environment into multiple areas are to facilitate growth and scalability which reduces the size of the LSDB
3. The difference between ABR and ASBR is ABR transmits network info btween the backbone and other areas while ASBR injects routing info from the outside the OSPF AS.
4. Common OSPF area types and their functional considerations: NSSA STUB STUB has no external routes. NSSA allows external routes to be flooded within an area.

1. When a routr receives a BGB route with its own AS number in it’s AS path, AS won’t react as quickly as an IGP.
2. The advantages of loop back peering for IBGP sessions is that if a failure occurs, the sessions will not go down because there will be other working links
3. The default BGP advertisements rules are IBGP peers advertise routes received from EBGP peers to the other IBGP peers. EBGP peers advertise routes learned from IBGP/EBGRP peers to other EBGP peers, but IBGP peers do not advertise routes received from IBGP peers to other IBGP peers.
4. Show route receive-protocol bgp neigh, show route advertising-protocol bgp neigh, show route protocol bgp.

1. Common reasons to use IP tunnels: backup links, connect to a company network, connecting networks together over the internet.
2. Diff. between GRE and IP-IP are when configuring them, the interface forms are different, GRE can connect isolated IPv6 networks, IP-IP encapsulates one packet in another packet.
3. The key requirements for GRE and IP-IP tunnels: A tunnel interface is required on each tunnel endpoint. An end to end communication path is required.
4. The route for the remote tunnel endpoint cannot use the tunnel interface as the next hop. If this happens the tunnel will bounce.

1. The basic operations of GR are that it allows uninterrupted packet forwarding and temporary suppression of all routing protocol updates. It also enables a router to pass throuh intermediate convergence states that are hidden from the rest of the network.
2. The key benefit to a graceful routing engine switch over is it allows a Junos device with redundant REs to continue to forward packets even if a RE fails.
3. Benefits of using BFD are rapid detection of link failures and once a BFD session is established, BFD continuously sends “hellos” to monitor the link.
4. The purpose of the virtual router in VRRP is the virtual entity that functions as a default router.

Continue reading »]]> When running a computer repair business it is important to back up your data. You may have critical information relative to your customers. This information may be names and addresses saved for marketing tactics or credit card numbers for customers that are on a billing plan. The information may also just be saved for future reference in case the customer returns for further assistance.
Getting new customers everyday would mean that the data needing to be saved changes everyday, if you were to lose your data you may not be able to contact a customer once their computer is done. This would lead to the customer having to call themselves to see if the machine is fixed. There’s a good chance this client may not return because of this.
A full back up should be done quarterly on whenever business is slowest, with incremental backups done every night at the end of each business day. A full back up quarterly would save a lot of time by not having to reinstall not only personal files that may be on the machine (music, graphics, etc.) but also any operating systems, programs, drivers, utilities and system files too. Incremental backups every night would not only assure that you don’t lose important customer records, but would also grab other useful data also. A full back up could also save you from losing your operating system as well as any updates or patches previously installed.
The only type of network backup I could think of that would be needed in a computer repair business is backing up data to a location outside of the business. For example to a backup server at home or even one hosted by a pay-for company. The advantage of this is if your business was to ever set fire, flood or fall victim to theft, your data would be safe.
If you’re paying a company to hold your data, an upside could be that you don’t have to physically store it anywhere. Other advantages include the chance that the user does not have to change tapes, label CD’s and other manual labor. Companies may also keep a list of versions of your files if you’re paying for your data to be stored.
On the other hand, disadvantages include having to pay the company to store your data (usually a monthly or yearly fee), slower transfer rates, data must be recovered via internet or post office shipment, service providers don’t always guarantee data privacy and, there may be backup limits as well. There are a few disadvantages I’m not going to get into.
Another option you could go about using is an Optical Jukebox. It can load and unload discs such as DVD, Blu-ray, compact and Ultra Density Optical. Information can be saved for up to 100 years and be accessed at high transfer rates. Although Optical Jukeboxes can hold very large capacities of data, using this type of storage used to be more price efficient than it is now due to hard drive storage becoming so cheap.
In larger companies, the amount of users needing access data stored by a Jukebox could become an issue, but due to the nature of a computer repair business, this should not be much of an issue in most cases. Although it could if you’re a company as big as Staples (EasyTech) or Best Buy (Geek Squad), it may take a lot longer to access data depending on the amount of users attempting to gain admission to it. Even with all that said though, optical drives are usually the best option for large quantities of audio, image and video files. Although hard disks have gotten cheap, 100GB of optical disc storage is cheaper in most cases then 100GB of hard drive space.
Now after you explaining a bit better about what you exactly wanted in this paper, and not just going by what was on the Lab…10 sheet was it? I’ve come to realize a little more on point of what you’re looking for. In a computer business with say, 3 locations in the Monmouth County area, I would do a full backup anytime there were any major system updates, or every quarter of a year. As far as incremental updates go, I would probably do incremental updates at the end of each day using something simple like a CD burner. Whoever was to close the shop for the day would be responsible for the update.
Now if I wanted something a little more automated, I would probably just go with an external hard drive at a central location and have all data backed up to there. Maybe even keep it at my home where it’s safe. If anything were to happen to the data, chances are it would still be at the location assuming all 4 (including my home) locations weren’t flooded robbed or set fire.
If data at one location were to go missing, it wouldn’t be that big of a deal because it wouldn’t stop me from running my business. This allows me a lot of free play as far as what option I’d like to choose to backup. I can pretty much just figure out the bare minimum cost of backing up and go with that method. Mohammad said the average life expectancy of a hard drive is five years. With this said I would maybe compare the amount of CD’s I would use per 5 years versus the external hard drive that I would have to replace every 5 years. Obviously as technology advances, the cheaper method may change.
I would use the dump and restore command, not a GUI. To backup a file or directory I would use dump -0uf databackup /home/mat/data. 0 would be a full backup and can obviously be changed, databackup is a backup file and /home/mat/data is the directory for which a backup is created.

To restore: restore -if databack.
The “i” is for interactive mode, “f” is to restore from the specific backup file and databack is a name of backup file/dump file.

Cron file example for backing up daily 11:10pm and on the 5th of every month at 12:05am:
Shell=/bin/bash
Path=/sbine:/bin:/usr/sbin:/usr/bin
MAILTO=root
# HERE IT WOULD RUN DAILY 10 MINUTES AFTER 11PM WHEN SHOPS ARE CLOSED
10 23 * * * $HOM/bin/daily.job >> $HOME/tmp/out 2>&1
# HERE IT WOULD RUN FIVE MINUTES AFTER MIDNIGHT AT THE 5TH OF EVERY MONTH.
5 0 5 * * $HOME/bin/monthly

Continue reading »]]> Offering Computer Repair in Middletown NJ, Old Bridge, Holmdel, NJ, Red Bank, Atlantic Highlands NJ, Hazlet, Union Beach, NJ, Port Monmouth, Leonardo, NJ, Belford, Aberdeen, Keyport, NJ, Matawan, Marlboro, Sea Bright, Tinton Falls, NJ, Asbury Park, Woodbridge, Sayreville, NJ, Toms River, Edison, Elizabeth, NJ, Jersey City, Newark, New Brunswick, NJ, Piscataway, East Orange, NJ, Lakewood, Clifton, Hamilton, NJ, Monmouth Beach, Long Branch, NJ. Those are just the main locations we service, if you’re located outside of NJ that’s okay too! We do remote computer repairs (we can fix your computer remotely from our office) and offer phone tech support!

and REMEMBER we are the !

Continue reading »]]> I so often see the question, “Is online/remote computer tech support safe?” Well let’s look at the facts. As new of an idea as this may seem to you, remote support has been around for years now. The concept isn’t all that complicated once the software is in place. An online computer support technician assists you in downloading remote repair software (if necessary), the PC tech then retrieves a one-time-use code, and then uses this code to connect to your computer.
It’s a quick, convenient process that allows you to avoid the high costs of having a PC support tech come to your home. This also helps you steer clear of having to lug around your computer and mess with a chaos of wires. Not to mention the best part of this all, you’re computer is fixed quickly and right in front of your face! Call up some computer support shops, ask them if you can watch over their shoulder while they speed up your computer (or give your computer a tune-up as some call it). It’d be inconvenient for you and uncomfortable for them. That’s if they even agree to this of course, they may not be able to do this for insurance purposes alone.
Now let’s get to the one of the best parts of online P.C. tech support. Your files and computer are safe! If you take your PC into one of these local shops, do you know how easy it is for them to complete a 5 minute fix, then cause internal damage that will cost you triple, or even quadruple the price? It’s just like those untrustworthy mechanics out there. As sad as it is, they exist. They’re not thinking how maybe if they fix your machine for $30, for those 5 minutes of work, that you’ll be quick to come back time and time again. They’re not thinking how many potential customers they can obtain through word of mouth; they just want that quick $150. There’s nothing stopping them from going elsewhere on their next computer support service needed.
Okay, so your hardware may not be safe, what about your files? Are you sure you want to trust your files in the hands of another? Family photos, tax documents, credit card information, all just some of the stuff a PC support technician could possibly have access to if he desired. With remote PC repair, you can be sure that your hardware is not being swapped out or messed with and that your files are safe. Everything that the online PC support technician is doing is done right in front of your face. With a click or two of your mouse, or a press or two of your keyboard, the technician is locked out. Not that they would try anything with the chance that you’re watching your computer screen of course. Most also offer a “no fix no fee” guarantee!
Remember the case in 2007, where a woman filed a lawsuit against a national computer repair chain whose agent allegedly left a camera phone recording in her bathroom. There are many good people out there; it’s just extremely hard to figure out which ones you’re letting in your home, or giving access to your PC. So what is your safest bet? You’ve got it, online P.C. tech support, also known as remote P.C. tech support, or online computer repair.
Okay so your one of those people that is still hesitant to use your credit card online. In most cases, there’s nothing to worry about. Most online PC tech support sites will transfer your credit card details securely using HTTPS (Hypertext Transfer Protocol Service). So that’s still not good enough? Give your credit card provider a call and ask them how you’re protected against fraud. There’s a good chance you’ll be happy with the response. Ask if you’re responsible for fraudulent charges placed on your card. Credit card providers want you to use them for everything because they get a percentage of each transaction.
Online PC tehc support is affordable too! Low prices don’t always mean a scam or inexperienced service provider, it sometimes means lower overhead costs than renting out a whole store. Would you pay $1500 a month to rent a store if you could spend $500 on a computer and $1000 on a repair website?
Speaking of website, repair isn’t all that is offered by some of these remote tech support service providers. Other services include web design, online computer training and even child safety packages. Need a website for your business? Want to get a little more use out of an expensive computer? Need to keep your teen safe on the internet? Dr. P.C. Repair (http://www.drpcrepair.com & www.doctorpcrepair.com) is just one of a few remote pc repair providers that offer all of these great services.
Are you in need of computer services? How about web design? Try an online P.C. tech support service provider today! Monitor your children on the internet, and all of their internet activity. See who they’re talking to on Facebook and other social networking sites. Finally want to learn to use that computer that you have spent so much money on? Try online pc training! There’s no time better than today, and no safer place to start than a remote pc tech support website! Just be sure to use a company that has a money back guarantee P
This article was written for Dr. P.C. Repair

http://www.drpcrepair.com

http://www.doctorpcrepair.com

Continue reading »]]> One-Time Password Security Measures
One-Time Passwords (OTP’s) are exactly that, passwords that are only used one time. The passwords are generated one of two ways, time synchronized or counter synchronized. Both of these methods use the same algorithm to create the password. The good thing about OTP’s is that it creates strong security. Not only does a person have only 24 hours or less to grab a password, but if they gain access to the password they can only use it for one day. One-time passwords are defense against a hacker eavesdropping on a networks data to retrieve login information. This is known as a replay attack. The downside to one time passwords is the complicity. Users can not remember the passwords therefore they typically require a small piece of hardware that can be kept on a key chain just like a flash drive.
Users not having to remember their passwords can also be a positive thing too though, passwords can no longer be social engineered. Another common security breach that can now be avoided is passwords being written down and stuck onto a monitor or under a keyboard. This common mistake made by employees allows anything who can access the floor, to walk around and collect various passwords. This is a good scenario for using the clip boarding technique. Clip boarding is where an intruder walks around or even gains access to an area he is not authorized to because he is carrying a clip board. The clip board creates the image that the intruder is legit, and is authorized to be at a specific place, and therefore is not questioned.
The major problem before one-time passwords was probably that passwords were cached on the machine and or stored on servers. This enabled anyone who could gain access to the system to pull a password off of it. This was especially worrisome for laptop users because laptops can so easily be stolen, especially if left unattended.
One-time passwords are an amazing idea. Although companies still need to worry about information being social engineered and being stolen by operating system vulnerabilities, passwords being taken because of silly mistakes such as posting them on their monitor or desk can now be avoided. It also prevents more advance attacks such as a system being hacked and its’ passwords being decrypted. OTP’s are just one more step closer to top notch security.

Mathew Gajewski

http://www.drpcrepair.com

http://www.doctorpcrepair.com