Saturday, July 29, 2017

The Slide Fire Stock


http://www.slidefire.com/


Designed for use on all AR-15 rifles equipped with a carbine style buffer tube, the Slide Fire Stock supplies rapid fire capabilities with no permanent modifications to your rifle. The Slide Fire Stock allows the shooter to safely bump fire their AR-15 from the shoulder, effectively and legally simulating fully automatic fire, and allowing for an unprecedented measure of control that is severely lacking when attempting to bump fire a rifle in the traditional, "from-the-hip" manner. 

The Slide Fire Stock features a shelf that positions the shooter's index finger in a fixed position in front of the rifle's trigger. To fire, the upper receiver is moved forward with the support hand pushing on the forend, thereby bringing the trigger to the shooter's finger and discharging a round. The rifle's recoil causes the upper receiver to move rearward, allowing the trigger mechanism to reset. When the right amount of constant forward pressure is applied, the rifle will continue to fire as the trigger is brought forward and depressed by the shooter's stationary index finger, causing the gun to Bump Fire. With a little practice, the shooter will be capable of delivering accurate single shots, bursts, or even full magazine dumps on demand using the Slide Fire Stock. 

 





Thursday, July 27, 2017

Oil / Fuel Filter Sound Suppressors



Suppressing the sound of a gunshot may be important in hostile and non-permissive environments. The sound of a gunshot can alert others to your presence and draw unwanted attention to your activities. When a gun is fired there are two major sounds. First is the explosion of the round itself being fired and gasses escaping from the barrel of the gun, and second is the sound of the bullet breaking the sound barrier (340.29 meters per second at sea level) if you are shooting supersonic ammunition. There is also the sound of the cycling of the firearm, but this noise is insignificant when compared to the sound of the shot itself.

To suppress the sound of a gunshot you need to resolve the two major sources of noise associated with the shot. We resolve the sound of the bullet breaking the sound barrier by using subsonic ammunition - that is bullets that travel slower than 340 meters per second. The problem of suppressing the sound of the round being fired is where suppressors / silencers come into play. In some countries you can buy a suppressor for your firearm with no more effort than buying the firearm itself (i.e. Norway and Poland). In other countries, the United States and the Czech Republic for example, suppressors are highly regulated and require additional applications and fees. If you are in a country that does not restrict the ownership of suppressors, or if you are able to obtain a permit to own a suppressor it is worth having one for any of your firearms where you can use subsonic ammunition.

While modern commercial suppressors can be somewhat complex in their design, suppressing the sound of a gunshot is not particularly difficult. It is interesting to note that a commonly available vehicle oil or fuel filter attached to the end of the barrel of a firearm will significantly reduce the sound of the gunshot. To use an oil or fuel filter as a suppressor you will need a threaded barrel on your firearm, an adapter with internal threads to match the barrel threads and external threads to match the oil / fuel filter threads. This is commonly ½-28 internal thread and ¾-16 external thread. These adapters are sold in many places for building solvent traps. Once you attach an oil or fuel filter to your firearm using this adapter you have a solvent trap, because one end of the filter remains closed. By drilling a hole in the end of the filter that lines up exactly with the barrel you have cleared a flight path for the bullet and created a basic sound suppressor.

More complex suppressors can be built from parts kits using Mag-Light flashlights as the suppressor tube (solvent trap tube), or from kits specifically designed to build suppressors (solvent traps), but as an expedient means the oil or fuel filter is quite effective.

A series of YouTube videos on building a "Fuel Filter Silencer" can be found here: https://www.youtube.com/watch?v=kP_BIb_OHZI, and "Hickok45" demonstrates an "Oil Filter Suppressor" on his YouTube channel here: https://www.youtube.com/watch?v=7t_pcWPdSDs.      

Wednesday, July 26, 2017

Data Privacy and Security



66 Ways to Protect Your Privacy Right Now
Do one, some, or all. Each one will make a difference.

http://www.consumerreports.org/privacy/66-ways-to-protect-your-privacy-right-now/

1. Check Your Data Breach Status
3. Use 10-Minute Mail
16. Use a Password Manager
32. Use a VPN
49. Embrace Encryption
55. Add HTTPS Everywhere
65. Make Google Forget You


US Army Cyber Crime Investigation Unit
Cybercrime Prevention Flyers

http://www.cid.army.mil/cciu-advisories.html

Cyber Crime Prevention Flyers provide recommendations to strengthen your cyber security posture and prevent computer crime before it occurs.

  • Online Scams - Soldiers are being targeted by cyber criminals intent on extorting money from them
  • Non-consensual Pornography - Distribution of sexually explicit images may violate existing Federal laws or the Uniform Code of Military Justice
  • Cyber Sextortion - Stay safe looking for love online
  • Protect Your Personal Email Account - Your email could be compromised
  • IRS Phone Scams - Avoid tax telephone scams 
  • Motor Vehicle Exploits - Auto hacking, it's not a myth
  • Online Misconduct: Awareness and Reporting - Improper behavior online
  • Don't scan your CAC! - DO NOT download or use anyapplication designed to read your CAC
  • Extortion scams - Data breaches and your personally identifiable information
  • USAJOBS warning - USAJOBS warns users of email phishing scam
  • Home Computer Security Tips - Safe computing practices for the home
  • Social Networking Safety Tips - Configuring Facebook, Twitter, LinkedIn, and Google+ for a more secure social networking experience
  • Twitter Safety Tips - Configuring Twitter for a more secure social networking experience
  • LinkedIn Safety Tips Configuring LinkedIn for a more secure social networking experience
  • Google+ Safety Tips - Configuring Google+ for a more secure social networking experience
  • Facebook Safety Tips - Configuring Facebook for a more secure social networking experience
  • Apple Mobile Device Ransom Scam - Apple Mobile Device Ransom Scam
  • Cybercriminals Target USAA Members - Fake customer incentives
  • Held for Ransom Part II - Ransomware


Best Practices for Keeping Your Home Network Secure (Updated)
https://www.iad.gov/iad/library/ia-guidance/security-tips/best-practices-for-keeping-your-home-network-secure-updated.cfm


SANS - Securing The Human - Security Awareness Newsletter

OUCH! is the world's leading, free security awareness newsletter designed for everyone. Published every month and in multiple languages, each edition is carefully researched and developed by the SANS Securing The Human team, SANS instructors and members of the community. Each issue focuses on and explains a specific topic and actionable steps people can take to protect themselves, their family and their organization. OUCH! is distributed under the Creative Commons BY-NC-ND 4.0 license. You are free to distribute OUCH! as part of your security awareness program or share OUCH! with your family, friends and coworkers. The only limitation is you cannot modify nor sell OUCH!. All translations are done by community volunteers. As such, at times some languages may not be available.

https://securingthehuman.sans.org/resources/newsletters/ouch/2017#2017

  • July 2017 Gaming Online Safely & Securely 
  • June 2017 Lessons From WannaCry 
  • May 2017 Securing Today's Online Kids 
  • April 2017 Passphrases 
  • March 2017 Securely Using Mobile Apps 
  • February 2017 Staying Secure on the Road 
  • January 2017 Social Engineering 
  • December 2016 Securely Disposing of Your Mobile Device 
  • November 2016 Using The Cloud Securely 
  • October 2016 Four Steps to Staying Secure 
  • September 2016 Email Do's and Don'ts 
  • August 2016 Ransomware 
  • July 2016 CEO Fraud 
  • June 2016 Encryption 
  • May 2016 Internet of Things (IoT) 
  • April 2016 I'm Hacked, Now What? 
  • March 2016 What Is Malware? 
  • February 2016 Securing Your Home Network 
  • January 2016 Securing Your New Tablet 
  • December 2015 Phishing 
  • November 2015 Shopping Online Securely 
  • October 2015 Password Managers 
  • September 2015 Two-Step Verification 
  • August 2015 Backup & Recovery 
  • July 2015 Social Media 
  • June 2015 Educating Kids on Cyber Safety 
  • May 2015 Securing the Cyber Generation Gap 
  • April 2015 Passphrases 
  • March 2015 Gaming Online Safely & Securely 
  • February 2015 Staying Secure on the Road 
  • January 2015 Securely Using Mobile Apps 


The Complete Privacy & Security Desk Reference: Volume I: Digital

This textbook, at nearly 500 pages, will explain how to become digitally invisible. You will make all of your communications private, data encrypted, internet connections anonymous, computers hardened, identity guarded, purchases secret, accounts secured, devices locked, and home address hidden. You will remove all personal information from public view and will reclaim your right to privacy. You will no longer give away your intimate details and you will take yourself out of 'the system'. You will use covert aliases and misinformation to eliminate current and future threats toward your privacy & security. When taken to the extreme, you will be impossible to compromise.





Tuesday, July 25, 2017

SOG ToolLogic Folding Knife




A great choice for rugged use anywhere life takes you, the Tool Logic SLPB2 professional grade, multi-functional folding knife is highlighted by a 3-inch razor sharp half-serrated blade made from rugged stainless steel. It's complemented by a brilliant removable LED flashlight that also includes a magnesium alloy fire starter. The SLPB2 also offers a stainless steel pocket-belt clip, and lanyard hole.

The brilliant white LED flashlight is detachable from its sleeve attached to the top of the knife handle, and it features an integrated premium magnesium alloy fire rod that is rated for hundreds of strikes. It throws off an intense shower of sparks at over 2500 degrees. The flashlight is made of tough anodized aluminum and is waterproof for use in wet environments or for shallow immersion.

Buy Here on Amazon.Com



Monday, July 24, 2017

OSA Nonlethal Pistol





OSA (Russian: ОСА, "wasp") is a family of Russian non-lethal pistols that can be also used as flare gun, flashbang gun or starting pistol. The system consists of the gun (2-4 cartridges, laser target pointer, electronic ignition capsule), and various ammunition types. In Russia the Osa is available to civilians as well as police but in the West it is mostly restricted to police use.



Sunday, July 23, 2017

Dead Drops



A dead drop (or dead letter box) is a method of espionage tradecraft used to pass items or information between two individuals (e.g., a case officer and an agent, or two agents) using a secret location, thus not requiring them to meet directly and thereby maintaining operational security.

A dead drop is simply an agreed upon spot where you or your contact can leave a message for the other without actually meeting in person. These are typically used in conjunction with a "Signpost," or a place to leave a signal that the message has been dropped.

Of course, you do not need to be engaged in espionage to make use of a dead drop.  Anytime you need a clandestine way to pass messages or materials to someone, the dead drop can be used.

Dead drops need to be arranged in advance. Find locations where you can place and retrieve materials without being seen. The dead drop location should be easily accessible, 24 hours per day, and should be relatively easy to access. At the same time however, the dead drop location should not be a place where a passer-by, children playing, or others are likely to discover or disrupt it.

The signpost is a place where a signal is left when the dead drop is loaded (load signal) and a second signpost is used to indicate that the dead dropped material has been recovered (unload signal).  The signpost need not be an actual signpost, rather it is anything that signals a change in the dead drop condition. A mark of chalk on the corner of a building is a common signpost method, but you can no doubt think of many other signals.

A couple of YouTube videos describe dead drops.

Above the Tearline: Brush Passes and Dead Drops

Black Scout Tradecraft- How to Use a Dead Drop 




Ghost: Confessions of a Counterterrorism Agent
by: Fred Burton
















Saturday, July 22, 2017

Search Engines That Do Not Track You


Google, Bing, Yahoo, Yandex - all the major search engines track your search history and build profiles on you, serving different results based on your search history. Usually your searches are saved along with the date and time of the search, some information about your computer (e.g. your IP address, User agent and often a unique identifier stored in a browser cookie), and if you are logged in, your account information (e.g. name and email address). With only the timestamp and computer information, your searches can often be traced directly to you. With the additional account information, they are associated directly with you.

Search engines that don't track your searches include:

DuckDuckGo - https://duckduckgo.com/

Startpage - https://www.startpage.com/

Ixquick - https://www.ixquick.com/

Disconnect Search - https://search.disconnect.me/

Lukol - http://www.lukol.com/

MetaGer - https://metager.de/en  

If you are concerned with your on-line privacy, you should start using one of the above sites for your searches.


* The DuckDuckGo privacy page (https://duckduckgo.com/privacy) provides a detailed discussion about why you should be concerned about search engine tracking.

Startpage and Ixquick  are run by the same company. In the past, Startpage returned Google results, while Ixquick returned results from a number of other search engines, but not Google. The two services have now been combined, and both return identical Google results. Although no longer actively supported, the old Ixquick metasearch engine is still available at Ixquick.eu. Interestingly, despite no longer being actively supported, Startpage has recently removed Yahoo results from the legacy search engine. This is in response to news that Yahoo has been helping the NSA spy on its users.



Friday, July 21, 2017

Universal Edibility Test


Just because you can live without food doesn't mean you should. Going without food will leave you weak and apt to make poor decisions, which could endanger your life in a survival situation. Being able to identify edible plants in the wilderness is a good skill to have. If you're in a survival situation and you don't know which local plants are edible, there is a test you can perform to give yourself a good chance of eating the right thing. It's called the universal edibility test.

The universal edibility test requires breaking down the parts of a plant and testing them individually over a period of 24 hours. In a survival situation, you don't want to go through this trouble if there isn't a lot of the plant you're testing. If there are only a few sprigs of what you think might be the colorful and edible borage, it won't help you much even if you find that it is edible. Find something near you that's growing in abundance. To prepare for the test, don't eat or drink anything but water for at least eight hours beforehand. If you're lost or stranded in the wild without any food, this should be pretty easy to accomplish. Now it's test time:

  • Separate the plant into its various parts - roots, stems, leaves, buds, and flowers. Focus on only one piece of the plant at a time.
  • Smell it. A strong, unpleasant odor is a bad sign.
  • Test for contact poisoning by placing a piece of the plant on your inner elbow or wrist for a few minutes. If your skin burns, itches, feels numb, or breaks out in a rash, don’t eat the plant.
  • If the plant passes the skin test, prepare a small portion the way you plan to eat it (boiling is always good).
  • Before taking a bite, touch the plant to your lips to test for burning or itching. If there’s no reaction after 15 minutes, take a small bite, chew it, and hold it in your mouth for 15 minutes. If the plant tastes very bitter or soapy, spit it out.
  • If there’s no reaction in your mouth, swallow the bite and wait several hours. If there’s no ill effect, you can assume this part of the plant is edible. Repeat the test for other parts of the plant; some plants have both edible and inedible parts.





Wednesday, July 19, 2017

ProtonMail and Tutanota








Many of us use Yandex Mail for our personal e-mail accounts. Yandex is a great company, providing a very efficient e-mail service, but an e-mail service that unfortunately in not very secure. (Think of Yandex Mail like the America-based Gmail. An e-mail system where all of your messages can be read by 'Big Brother' and Big Business.) 

If you are looking for more secure and private e-mail, consider Proton Mail (based in Switzerland) and Tutanota (based in Germany). Both of these e-mail providers are focused on privacy and security, and both are located outside of the country, making it much more difficult for the service provider to be pressured to turn over any information about your account.

So, consider setting up a Proton Mail or Tutanota account (or both) and improving the security of your e-mail today.


Monday, July 17, 2017

Primitive Traps



How to Build a Small Game Survival Snare

For short term survival (1-7 days), food is not a critical priority.  Shelter, water, fire, and signaling are typically more immediate concerns.  At some point, though, you must put calories on the human furnace or suffer the debilitating consequences of starvation.

To my knowledge there isn’t one single primitive culture, tribe, or people where meat is/was not a critical component of their diet.  Modern equipment, farming, transportation, food processing, supplements, and complex supply chains give us the option not to eat meat if we choose.  Remove these luxuries for an extended period of time and the calories from meat once again become necessary for survival.  It would be extremely difficult, if not impossible, to source enough calories in a primitive survival scenario by gathering wild plant edibles alone - especially in cold weather climates or seasons.

Time and energy conservation are both very important factors to consider in any survival situation.  This is precisely why snares are such an important survival tool.  Once constructed and set, a snare will allow you to focus on other survival priorities.  And, it will keep working even while you are sleeping.  With 10 snares you can be hunting in 10 different locations at the same time while expending ZERO energy.  You become a one man hunting party.  Snares are a survivor’s secret weapon.  Not only are snares incredibly reliable and effective, they also require very few resources to build - in materials, energy, and time. (Read the rest of this article here.)


Videos:

Survival Trappers Bible Part 7 Spring Pole Peg Snare (YouTube Video)

Deadliest Small Game Primitive Trap (Windlass Trap) (YouTube Video)

Mojave Scissor Survival Trap (YouTube Video)


Articles:

Six Primitive Traps For Catching Food In The Woods

How to Build a Trap: 15 Best Survival Traps


Buy Professional Snares Here (Pack of 12)

Buy A Survival Snare Package Here


Books:

The Trapper's Bible: The Most Complete Guide on Trapping and Hunting Tips Ever 

The Bushcraft Field Guide to Trapping, Gathering, and Cooking in the Wild

How to Eat in the Woods: A Complete Guide to Foraging, Trapping, Fishing, and Finding Sustenance in the Wild



Saturday, July 15, 2017

VPN companies are going to face problems from Russia


In Russia, the Republic Duma, the lower house of the Federal Assemblage of Russian legislature, unanimously approved the first version of the new law that would forbid the use of VPNs as well as online anonymizers like the Tor browser if they don’t block access to web-sites on a government-run list.

That list of websites will include any sites that produce software that can bypass the restriction. The government also wants search engines to exclude references to blocked websites so civilians don’t recognize what it is they are not entitled to see.

The bill was passed in record time following FSB Director, Alexander Bortnikov, presenting an hour-long lecture to Duma delegates in a private meeting, in which he told how serious it was that the law was enacted and passed quickly. 

In a letter describing the law, Duma delegates argue that the bill is necessary because the current censorship appliance in place is "not effective enough."

An another law that also claimed its first section this period will require mobile phone operators to:
  • Recognize specific users
  • Block communications if requested to do so by the state
  • Allow the jurisdictions to send their own messages to all users

Any businesses that fail to comply with the laws can be fined up to one million rubles ($16,500).







Wednesday, July 12, 2017

Padlocks


Padlocks are portable locking devices commonly used on school and gym lockers, toolboxes, gates, sheds, storage lockers, and in combination with a chain or cable to secure bicycles, scooters, and motorcycles. No doubt you can think of many other uses for padlocks, as well.  When choosing a padlock there are several things to look for to ensure you are getting the best security for your money.

Choose a padlock that has a:

  • Heavy solid steel or laminated steel body.  Generally speaking larger, heavier padlocks are more resistant to force than smaller, lighter padlocks.  
  • Hardened molybdenum or boron alloy shackle with a diameter of at least 9mm.  Use a closed (shrouded) shackle if your application will allow it.  This adds resistance to bolt-cutter and hacksaw attacks.    
  • Pick resistant keyway, with a minimum of six pins in a pin/cylinder lock.  Most padlocks are easily picked open.  More pins, and pick-resistant keyways help mitigate this weakness.
  • Dual ball bearing locking system.  This resists shimming attacks.
  • Anti-drill plate protecting the keyway.

All else being equal, combination padlocks are less secure than padlocks that are opened with keys.  Most combination padlocks can be manipulated and opened without knowing the combination, just as most keyed padlocks locks can be picked.  It is however easier to find keyed padlocks that are resistant to picking than it is to find combination padlocks that are resistant to manipulation.
Some high security padlocks, such as the Abloy PL362, Abus Granit 37/80, or the Medeco Protector II (each of which I recommend)provide excellent security, however each of these padlocks costs over 5000 rubles, which may be more than you want to spend for a general use padlock.
 
For general, lower security, use (say on a gym or school locker), in a padlock costing around 1200 rubles, I recommend the Stanley 24/7 padlock for a keyed lock and the Master 2002 padlock for a combination lock (avoid the Master 1500 series padlocks).  The Stanley 24/7 and the Master 2002 padlocks each provide good security at a reasonable price for general daily use.




Tuesday, July 11, 2017

Diceware Passphrase Generator


Secure passphrases (passwords) can be generated by hand, using a system called Diceware. Diceware uses rolls of dice to generate random numbers that correspond to a word-list. Each Diceware generated word has 12.9 bits of entropy, so you will need to generate five or six words to make a strong pass-phrase. 

Most importantly a password should have a high degree of entropy (randomness or lack of order or predictability). Generally speaking, we recommend that a password have at least 40-bits of entropy, with 80-bits or more of entropy being preferred. The Rumkin Password Strength Test allows one to test the strength of different types of passwords on-line. The Rumkin Password Strength Test is useful for testing various password formats for entropy, but note that we differ slightly on the bits of entropy needed for a secure password. 

The Diceware word list can be downloaded from their web-site and used to generate a strong, yet easy to remember passphrase for use with encryption and security programs.

In July 2016, the Electronic Frontier Foundation (EFF) published their own wordlist for generating pass-phrases from dice rolls. Both the Diceware and EFF lists provide the same degree of entropy, but the EFF claims that their list uses more memorable, and more easily spelled words.  

Regardless of whether you use the EFF or Diceware list, what is important is that you generate strong, memorable, passphrases to protect your on-line accounts, encryption, and security programs.




Sunday, July 9, 2017

Siberian Big Log Fire



Yesterday, I wrote about the Dakota Hole Fire. This fire is small, concealable, and very efficient for cooking or boiling a pot of water. What the Dakota Hole Fire doesn’t do well however is keep you warm on a cold winter night. To use a fire for warmth, you need a large fire that reflects heat into your shelter.

The Siberian Big Log Fire is an excellent choice for staying warm. To build a Siberian Big Log Fire you need a base log. At a 90-degree angle to your base log, lay other logs across the base and extending over it. Build your fire in front of the base log, on a platform, and under the over-hanging logs. The over-hang logs burn, and at the same time serve as a reflector, directing the heat of the fire into your camp. As the over-hang logs burn away, you simple feed them forward from the back of your fire.

Survival Russia has an excellent demonstration of the Siberian Big Log Fire on his YouTube channel.

In a winter camp, a small fire simply won’t keep you warm throughout the night. The Siberian Big Log Fire will however produce plenty of heat, reflect that heat into your shelter and allow you to stay warm during a cold night in the forest.





Saturday, July 8, 2017

Dakota Hole Fire


A Dakota Hole Fire is a fire that is built below the surface of the ground. This shields the flame and helps to keep it from being seen at night. If you use dry wood, the Dakota Hole Fire produces less smoke, and by building your fire at the base of a large tree, what smoke there is will be defused by the tree branches as it rises. When you are done with the fire, evidence of it is easily hidden by filling in the hole and covering the surface with normal ground cover from the area.

To build a Dakota Hole Fire, first dig a hole for the fire itself. This hole should be about 25 - 30 cm deep and maybe half that in diameter. Move about 25 cm from the fire hole and dig a second similar hole. Connect the two holes with a tunnel at their base. The second hole should be angled a bit toward the base of the fire hole to help air flow.

Fill the fire hole with kindling and get it burning. Continue to add bigger pieces of wood as your fire grows. The fire creates a draft which draws air into the second hole and to the base of the fire hole. This air flow results in a much hotter and more efficiently burning fire.



Friday, July 7, 2017

Virtual Private Networks (VPN)


In the simplest terms, a VPN is used to create a secure, encrypted connection - which can be thought of as a tunnel - between your computer and a server operated by the VPN service. In a professional setting, this tunnel makes you part of the company's network, as if you were physically sitting in the office - hence the name.

While you're connected to a VPN, all your network traffic passes through this protected tunnel, and no one - not even your ISP - can see your traffic until it exits the tunnel from the VPN server and enters the public internet. If you make sure to only connect to websites secured with HTTPS, your data will continue to be encrypted even after it leaves the VPN.

The protection provided by a VPN offers users many advantages. First and foremost, it prevents anyone on the same network access point (or anywhere else) from intercepting your web traffic in a man-in-the-middle attack. This is especially handy for travelers and for those using public Wi-Fi networks, such as web surfers at hotels, airports, and coffee shops. VPNs also cloak your computer's actual IP address, making it harder for advertisers (or spies, or hackers) to track you online.

The right VPN can protect against lots of things, including government surveillance and malware. But the tool isn’t a magic privacy bullet - in fact, experts can’t even agree on a great VPN service, beyond one you make yourself. While a huge number of companies provide VPNs, many have potential security flaws or could put your data at risk. It’s also difficult to tell how secure a VPN actually is, and what it’s doing with your data. So what are you supposed to do if you want to use one? The short answer is to avoid free services, and if you consider yourself tech-savvy, look into setting up your own. Otherwise, make sure a paid VPN has a privacy policy you’re okay with, and can handle the threats you’re relying on it to protect you from.




Wednesday, July 5, 2017

Knife Fighting


In his book All-In Fighting, W.E. Fairbairn wrote: "The knife in close-quarter fighting is the most deadly weapon to have to contend with. It is admitted by recognized authorities that for an entirely unarmed man there is no certain defense against a knife." The knife, in trained hands, can be a very effective and deadly means of personal protection. In the hands of a criminal it can also be a very deadly means of assault. While any knife may be used for personal protection, a knife specifically designed for fighting is the best choice for the person who chooses to carry a knife for protection. Rex Applegate wrote in Kill or Get Killed: "When a man has a weapon which he knows is designed for fighting alone and has been trained in its use, he immediately develops a sense of confidence in it that he will never feel toward the utility knife. His fighting knife takes on a definite personal characteristic. He carries it with him at all times, he sharpens it often, and he will regard it as a very necessary part of his personal equipment." If you need a knife for utility purposes then carry a utility knife or a multi-tool, but let your personal protection knife be a dedicated fighting knife.

So what knife should you carry for close-quarter fighting? The Fairbairn Fighting Knife is an excellent choice, as is an updated version of this knife, the Gerber Mark II Knife. These are fixed blade fighting knives, and will likely be deemed "illegal" in places with oppressive governments. In such case, be sure that you keep your knife concealed, or carry a smaller folding knife such as the Gerber Applegate Combat Folding Knife. 

To learn knife fighting, it is of course best to find an expert to teach you to use your knife effectively. Still, it may be possible to learn a few basic techniques from books and videos, and even these basic techniques can save your life once you are confident with your knife.

Into the Fray Episode 168: Basic Knife-Fighting Techniques 

Military Training with a Knife (Russian)