Should I Use Another DNS Server?

Should I switch my current DNS server?

If you are just a regular Internet user (not self-hosting anything), and you are currently using your ISP’s DNS server, I would switch to a 3rd party DNS service (e.g. Cloudflare).

However if you are self-hosting anything (e.g. email), then I would opt for running my own DNS resolver for reliability.


Here are my opinions on the three typical ways to get DNS.

ISP DNS Resolver:  usually ok performance / no privacy

  • Works out-of-the-box with your Internet service.
  • Since you are using servers they control, always assume your ISP is logging your DNS requests (no privacy).
  • Sometimes an ISP actually has worse DNS servers (slower, less secure) than a 3rd party DNS service.
  • Many years ago, I made use of my ISP’s DNS resolving services. They would occasionally go down – every few months. It made it look like the Internet was “down”, but it was just their DNS resolvers that were down.

Third-Party DNS Resolver (e.g. Cloudflare, OpenDNS):  good-to-excellent performance / potentially less private

  • 3rd party DNS server may be logging your DNS lookups, regardless of what their Privacy Policy says.
  • Can be faster than your ISP’s DNS resolvers. This is due to 3rd party DNS services having a very large network infrastructure. They can handle large amounts of traffic with ease.
  • Cloudflare does support DNS-over-TLS. However this is just encrypting your connection to Cloudflare. When Cloudflare retrieves the DNS records for you – assuming they do not have a cached copy – that connection of theirs is unencrypted. This means the DNS records Cloudflare gets for you can be manipulated by a 3rd party, outside of Cloudflare’s control.
  • Any server hosting a website using SNI (Server Name Identification) – without using the TLS 1.3 protocol – will give the domain name you are accessing in plain-text for anyone to see. This defeats the purpose of using an encrypted DNS service.
  • Can help get around DNS blacklists your ISP may have implemented.
  • Unless you are using a VPN service, your ISP will still have to route your connection to the website. This may give away where you are going on the Internet, even if your ISP cannot read your DNS queries.

Self-Hosted DNS Resolver (e.g. Unbound DNS):  ok-to-good performance / potentially more private

  • Useful if you want to have reliable lookups, since your are cutting out the middle-man handling your DNS requests.
  • If you are self-hosting web services (e.g. web and email), it is recommended to run your own DNS resolver. While not necessary, this will help prevent interruptions to your services.
  • While there is no worry about the DNS server keeping logs (you are running it, after all), there still is the possibility of your ISP and/or other entities sniffing your DNS lookups and keeping a log that way. This is because DNS is inherently insecure (not encrypted).
  • Unbound runs on FreeBSD, OpenBSD, NetBSD, MacOS, Linux and Microsoft Windows.
  • Unbound DNS does require some knowledge of DNS to be setup properly.

Posted in Computers, Internet and Servers, Operating Systems, Security

The Windows Command Prompt is not DOS

A while back, I read on a website that the Command Prompt on the NT-based versions of Windows are somehow from MS-DOS. This is a myth.

While the Command Prompt (cmd.exe) does copy the commands from the MS-DOS (command.com) command line, this does not make the Command Prompt in Windows NT in any way, shape, or form, related to MS-DOS.

For example, I could write a C#.Net console application that mimics Linux bash commands, but that would not make my application “bash”.  I am just mimicking the commands from bash. The same applies for the Command Prompt on the versions of Windows NT. The Command Prompt may use the same commands as the MS-DOS one, but that does not make it DOS.


Here is a bit of information some people may find interesting.

32-bit Windows NT operating systems (e.g. WinXP, WinVista) can run DOS programs due to having a built-in 16-bit “NT Virtual Dos Machine” otherwise known as NTVDM. This allows people to run DOS programs (even full-screen ones) without much problems.

However the 64-bit versions of Windows do not have NTVDM. For the 64-bit Windows operating systems, an emulator (e.g. DOSBox) is required to run DOS programs.


Posted in Computers, Operating Systems, Software

How Secure are JavaScript Password Generators?

Many people use online services to generate secure passwords.

There is this idea that since your web browser is the one generating your passwords locally on your computer (via JavaScript) instead of someone else’s computer (e.g. web server), this is supposed to keep someone from getting a hold of your password.

Is this really the case? Are passwords generated locally with JavaScript really secure from being stolen?

Technically, no. Why? Well there are a few reasons why generated passwords (via JavaScript) can be compromised.


the [Math.Random] JavaScript function  –  Any JavaScript password generator that uses this function should be considered insecure. This is because the Math.Random function does not provide cryptographically-secure results. It is even possible to predict the output of Math.Random.

This means that someone could potentially generate the same password that you just generated a week before. Not the best for people who want to have secure passwords.

A good, secure alternative JavaScript function to use is window.crypto.getRandomValues(array).

Summary: Using any JavaScript password generator that makes use of the Math.Random function is not wise.


web browser add-ons  –  Many people use web browser add-ons (such as Ad-blockers) for their everyday browsing. What most people are unaware of is that many of these add-ons have permissions that allow the add-on to view the content of the web pages the user is viewing.

The problem? If someone has installed a malicious add-on, their “secure” JavaScript generated password would have been sent to the add-on’s creator. Now I am not implying that every single web browser add-on does this, but there is a very high potential that this can happen.

Would only using open-source browser add-ons be a safe option? Well open-source add-ons would definitely lower the chance that someone would get away with spying on you. However open-source projects do not have a spotless security track record either. There is still some risk.

Even Mozilla themselves warn about this problem with web browser add-ons (also called extensions).

Update 12/05/2019:  Here is another example of what I am talking about (https://www.zdnet.com/article/mozilla-removes-avast-and-avg-extensions-from-add-on-portal-over-snooping-claims/).

Summary: Several add-ons have the potential to spy on their users (including locally generated JavaScript passwords).


computer malware  –  This reason is arguably the most common cause of compromised passwords…malware. Malware has the potential to do anything it can to your computer (including reading your computer’s clipboard – what you copy & paste). This will instantly compromise your JavaScript generated password (and any other sensitive information on your computer, e.g. credit card numbers).

While Windows-based systems have more malware available for them, Mac and Linux are not completely in the clear either. As more people start using these other OSes, more and more malware will be created for them.

Android (the very popular Linux OS used on smartphones all over the world) has a good number of malware created for it.

Summary: Computer malware has the potential to instantly compromise your JavaScript passwords.


surveillance software  –  Some people have to use computers provided by their employer. Some employers put surveillance software onto their computers to track and monitor their employees’ usage of those systems.

The tracking software will monitor your computer screen, keystrokes, what you browse, install, etc. In other words, any generated password (JavaScript or no) on these computers will be compromised. It is advised to use non-work computers for generating passwords, or anything else that is not work related.

Summary: Assume any work computer is being tracked. Always use your own personal computer for anything non-work related.


So does this mean that I should never use any online password generators at all?

No, but just keep in mind that a JavaScript password generator, while technically a little more safe than having your password generated on a server and sent across the Internet, does not really provide a lot of extra security.

Summary: Using JavaScript (or anything else) to locally generate passwords on your computer, cannot keep your passwords completely safe from being compromised.


Posted in Android, Computers, Internet and Servers, Operating Systems, Programming, Security, Software

Dynamic and Static IP Address Differences

To access the Internet, your Internet Service Provider (ISP) assigns you an IP address. This allows you to talk to other computers on the Internet. Most people do not even think about their IP address they have been assigned, much less what type of IP address they have.

There are two kinds of IP addresses, static and dynamic.

Static addresses never change on you. Even after many months (or even years), the IP address you have been assigned stays the same. Dynamic addresses, on the other hand, usually change every few weeks (or months). Most people probably are assigned a dynamic address for a month or two at a time.

Pros of Static Addresses

  • Allows you to easily host web services (e.g. email, DNS, websites)
  • Helps prevent websites from mistaking you for being an abusive user. This is because when using a dynamic IP address, someone else had previously used that address, and may have been committing abusive behavior online. However, when using a static address, you (and whoever else has access) are the only ones using your address.
  • Allows for a more stable VPN connection, because a dynamic IP may change any moment, and this will break the VPN connection.

Cons of Static Addresses

  • ISPs usually require you to purchase a “business” Internet package to be able to obtain a static IP. This may cost more money per month than a typical residential Internet package.
  • Everywhere you go online can be easily tracked, since you use the same IP address everywhere you go online (a VPN can help with this problem).
  • If someone starts constantly abusing your IP address (e.g. DDoS attack), you likely will not be able to quickly request a new static IP address from the ISP.
  • If you have a unique host-name assigned to your static IP (usually necessary to host a email server), you will have less privacy than someone who has a typical residential, dynamic IP address without a custom host-name.

Pros of Dynamic Addresses

  • Usually can easily change your assigned IP address (helpful to stop someone who is abusing your computers; e.g. DDoS attack).
  • Since your IP address is “generic” (used by several other people), you are more anonymous than a static IP constantly browsing the web.

Cons of Dynamic Addresses

  • Hosting web services will not be very stable, since you are using a dynamic IP address that may change anytime on you (note: using a “dynamic IP” DNS service is more of a “jury-rig” than a proper solution).
  • Some web services may think you are a trouble-maker, since someone else may have had your IP address previously and used it to abuse web services.
  • ISPs may deny you the privilege of running any web services unless you have a “business”-grade Internet package (most people using a dynamic IP do not have a business account at their ISP).


Posted in Computers, Internet and Servers, Operating Systems, Security, VPN