Posted by: Yosef B. | May 1, 2019

Types of Firewalls

It’s been quite a while since my last post so here’s hoping I can keep the momentum going!

In this post, I’m going to walk through the four different types of firewalls and what they are best used for.

The four types of firewalls, from most basic to most complex include:

  1. Static Packet Filtering Firewall
  2. Stateful (aka Dynamic) Inspection Packet Firewall
  3. Circuit Level Proxy Firewall
  4. Application Level Proxy Firewall

Static Packet Filtering Firewalls
Static Packet Filtering Firewalls are the most basic type of firewall. The only type of filtering you can do is allow or block specific IP addresses and ports from entering or existing the firewall. I.e. you can block computers on your network from accessing Google’s DNS service by creating a block of any outgoing traffic to (TCP & UDP).

Benefits: Cheapest option, fast to apply rules

Drawbacks: Limited filtering abilities, cannot scan or inspect inside a data payload

Stateful (aka Dynamic) Inspection Packet Firewall
Stateful or Dynamic Inspection Packet Firewalls provide all the functionality of Static Packet Filtering Firewalls, plus they “inspect” and allow or block based on connection states. For example, the firewall can watch a TCP handshake being performed and determine if it is executed normally, or if there’s a denial of service (aka a SYN flood) attack occurring and then automatically block the incoming traffic, keeping your internal machines from being overwhelmed.

A typical TCP handshake occurs when a SYN request is sent from one machine to another, the second machine sends back a SYN and an ACK acknowledgment back to the requesting machine. The original machine then sends an ACK acknowledgement back completing the handshake and allowing communication to begin. If the original machine doesn’t send a second ACK acknowledgment and instead just continues to send a stream of SYN requests, the firewall will realize that the handshake is incorrect and block the flood of incoming SYN requests.

Benefits: Stronger filtering capabilities, retains (logs) state information about a connection for further offline analysis

Drawbacks: More expensive system, slightly slower filtering, still cannot inspect inside a data payload, requires static rules to allow unsolicited inbound traffic (e.g. email incoming to an email server)

Circuit Level Proxy Firewall
Circuit Level Proxy Firewalls provide all the aforementioned functionality of both the static packet filtering and stateful inspection packet firewalls. In addition, they provide Network Address Translation (NAT) and Port Translation.

Benefits: There is no direct contact between client and external server, internal IPs are hidden from external systems, malformed packets are dropped and not forwarded onwards

Drawbacks: Requires a minimum of 4 packets per round trip (e.g. client sends packet #1 to firewall, firewall repackages into new packet #2 & sends to external server, external server sends reply packet #3 back to firewall, firewall repackages into new packet #4 and sends to internal client), more expensive system than the previous two, still cannot inspect inside a data payload.

Application Level Proxy Firewall
Application Level Proxy Firewalls do everything the last three firewalls can do and in addition, can inspect inside data payloads! The firewall does this through proxies that are written for each service that’s required to pass through the firewall “air gap”. A proxy is a piece of software that’s customized to each service (e.g. HTTP, SMTP, FTP, etc.) and is able to unpack the data packet and inspect the data inside, and filters the content based on proxy rules.

Benefits: Can inspect inside data packets! Can even inspect inside encrypted payloads provided you have the requisite certificates to un-encrypt the payload and re-encrypt before sending onward.

Drawbacks: Most expensive option, much slower to filter data, not all services have proxies written and may require custom coding or a generic UDP/TCP proxy to essentially bypass the proxy filtering capabilities (i.e. it can’t scan inside the payload) and allow traffic through on a specific service port.

Posted by: Yosef B. | July 5, 2018

Editing Mozilla Firefox Container URLs

I really like Mozilla Firefox’s container system that’s been out for around a year now. There’s one issue though that’s bothered me on a daily basis and really annoyed me, I just never took the time until now to track down the fix for it. Hope this helps someone else!

I’m assuming that you use Mozilla’s Firefox browser and have already setup container groups and assigned specific websites to always open in container tabs. My issue was, I couldn’t figure out how to edit a URL once I set it up.

Well today I spent 10 minutes & figured out where Firefox stores the file that controls these URLs so you can manually edit them. The file is called storage.js and is stored in your Firefox profile which is typically in your user profile’s AppData folder (reachable at %AppData%). For me, this file is stored in:

%AppData%\Roaming\Mozilla\Firefox\Profiles\<PROFILE NAME>\browser-extension-data\@testpilot-containers

Before editing the file, close Firefox. You can open the file in any basic text editor (I personally use Notepad++ but regular Notepad works too) do a quick search for the offending URL and update it to the URL you want it to be, then restart Firefox and your URL should now redirect properly to the correct container group.

Note that the URL is only the top level domain. E.g. you can change to, however you don’t need to specify https://www before the domain name.

Posted by: Yosef B. | June 19, 2017

Setting Default PivotTable settings in Excel

Microsoft’s latest update to Excel now allows you to set defaults for how you want your PivotTables formatted. As someone who builds PivotTables all the time & 98% of the time want them setup the same way – this is a huge help!

To access the default options, open Excel and go to: File > Options > Data > & click on the Edit Default Layout button.

If you have an existing PivotTable that’s setup the way you want, simply use the Layout Import option at the top of the window to select the existing PivotTable and import the options all ready set.

The options I have set are:

  • Subtotals: Do Not Show Subtotals
  • Grand Totals: On for Rows and Columns
  • Report Layout: Show in Tabular Form
  • repeat All Item Labels: Checked box

In addition, click the PivotTable Options button and you can optimize all your PivotTables moving forward (huge file size saver!).

Select the Data tab and select/unselect the following options:

  • Save source data with file: Unchecked
  • Enable show details: Checked
  • Refresh data when opening the file: Checked
  • Number of items to retain per field: Select the None option

This will force excel to refresh the PivotTable every time the file is opened but it will also not save the source data (calculations behind the PivotTable) which makes the file size much smaller & less susceptible to file corruption.


Posted by: Yosef B. | June 13, 2017

Block all Windows notifications when Screen Sharing

I see it all the time – someone is sharing their screen during a meeting and an email notification pops up, usually to the audience’s amusement and the presenter’s chagrin.

There’s a simple trick you can do to block Windows (and Microsoft Outlook) from interrupting your screen sharing.

  1. Open the Windows (Start) menu and type “Present”.
  2. Select the first item titled “Adjust settings before giving a presentation”

  4. Click the check box at the top of the window that appears “I am currently giving a presentation”

    This will add the following icon to your icon tray:


  6. When you are done presenting, simply right-click on this icon and select “Stop Presentation”

Good luck with your presentations!

Posted by: Yosef B. | May 30, 2017

Taking control of Windows 10 System Updates

A number of colleagues seem to be having trouble with their Windows 10 PC’s restarting on them at inopportune times – here’s how you can take back control…


  • The options you see will depend on what settings your company/computer Administrator has set. If you don’t see a corresponding option to the steps below, please follow-up with your administrator to see if they can allow the option for you.
  • Click on any image below to enlarge.
  1. Open the Windows (Start) menu.
  2. Type “Windows Update” and select the “Check for updates” option from the list that appears.
  3. In the middle of the window that opens, under the Update settings section are three links to more advanced options:

    1. Change active hours
    2. Restart options
    3. Advanced options

    Select the first one: Change active hours

    Here you can set the normal hours that you work. Windows won’t restart your computer during these hours without at least warning you first. Feel free to buffer on both sides of your day to give yourself enough time to finish up before Windows decides to restart your computer for you. Click Save to save and exit this window to return to the other options.

    Note: If you don’t leave your computer running during non-work hours, you run the risk of not getting important security updates in a timely manner. To counteract this – make it a practice to manually check for updates on at least a weekly basis.

  4. Back on the Windows Update window, select the next option: “Restart options” to open the following window:

    Here you can set a scheduled time for Windows to apply updates. Best use of this is if you know you always leave your machine running over the weekend – schedule the updates to be installed on Friday night while you’re not at work.

    You can also elect to have Windows pop up with a reminder to tell you when it’s going to auto-restart your machine. If you’re getting blindsided by it auto-restarting – here’s the option you’ve been looking for!

  5. Go back to the Windows Update window to select the final option: “Advanced options” to open the following window:

    I recommend selecting the checkbox for “Give me updates for other Microsoft products when I update Windows.” This will help ensure other Microsoft products like Office are getting updates regularly as well.

    I do NOT recommend turning on the Pause Updates option. This is a big potential security risk if an important patch is deployed by Microsoft and you’ve paused the updates for a month (e.g. the recent WannaCry Ransomware patch).

  6. At the bottom of this screen is another link to the final set of options: “Choose how updates are delivered”

    These options allow you to get updates delivered to you quicker. Essentially – if any other computers on your local network have already downloaded the update you need, your computer will be able to get all or part of the update directly from them instead of having to go out to the web to re-download it. Since your local connection is usually much faster than your internet connection – this can save a bit of time & potentially internet bandwidth in getting updates delivered to your computer.

Hope this helps with your reboot woes – as always, let me know if you have any questions.

Posted by: Yosef B. | August 22, 2016

Understanding Windows Group Policy Changes

Whether you are a Sys Admin or a user, troubleshooting Windows Group Policy on a domain connected client PC can be difficult. Luckily through the use of a few free programs and a Windows built-in tool, you can make sense out of the Group Policies applied to a computer.

To get started, you will need software that allows you to compare two text or html files (I prefer working with HTML as it’s easier to read, but it can be a bit more tricky to understand the file differences). I use the free Notepad++ with its Compare plugin for this but you can also use the Windows 10 (Anniversary edition 🙂 ) Bash diff command, or Winmerge, etc. You can download Notepad++ for free here:

In addition, the Sys Internals ProcMon (Process Monitor) program is helpful for identifying which registry settings a Group Policy object modifies. You can download it for free here:

Finally, you need to get comfortable with the DOS command gpresult.

The basic process is as follows:

  1. Generate a Group Policy report using the gpresult command
  2. Review it to see which policies are applied
  3. Use the ProcMon program to monitor which registry settings are applied when you change a group policy
  4. Open / edit a Group Policy
  5. Rerun the gpresult command to generate a new report (make sure to change the name of your output file so you don’t overwrite it!)
  6. Compare the two reports using your program of choice to see what changed!

Step one: Export a list of all applied group policies on the Domain connected computer. To do so, open a DOS prompt in Administrative mode and type the following command:

gpresult /S Name_of_PC_Goes_Here /H “C:\output_file.html”

Where Name_of_PC_Goes_Here is the name of the PC that you’re trying to generate a Group Policy report for and the output_file is the path and name of the report that you’re trying to generate.

If you prefer a text file instead of HTML, remove the /H flag and just pipe the output into a text file, e.g.:

gpresult /S Name_of_PC_Goes_Here >”C:\output_file.txt”

Step two: Open file in editor/viewer of your choice to see what group policies are already in place.

Step three: Run ProcMon, press Ctrl+L to bring up the Process Monitor Filter, and then add the following filter conditions:

  1. Process Name is mmc.exe then Include
  2. Operations is RegSetValue then Include

Step four: Open the Group Policy editor and make any changes that you’re interested in.

Step five: Switch over to ProcMon and you should see the registry key(s) listed there. Right click on it and select the Jump To… option from the context menu to open up Regedit and take you to the exact key that was modified.

Step six: Rerun the gpresult command (remember to change your output file name so you don’t overwrite your first report!)

Step seven: Use your program of choice (e.g. Notepad++) to compare the two gpresult reports to see what changed.

Hope this helps! If you have questions leave a comment & I’ll get back to you as soon as I can.


I’m sharing this bug (maybe Microsoft considers it a feature?) as well as the (partial) solution so others can be aware that this issue occurs and how to avoid it in the first place.

The problem I discovered was that when sharing a copy of a Microsoft Office document (such as a Word, Excel, or PowerPoint file) using the built-in File > Share > Email > Send as attachment option from within the Office program, the body of the email sent sometimes would disappear! The person receiving my email would get a blank email with just a subject and attachment but no explanation!

After researching the issue, I know why it now happens – and for most folks the fix I found should work in all cases for you. Unfortunately, my own case is more complicated because as a consultant, in addition to my own company’s Microsoft Exchange Server email, I typically have a client’s Microsoft Exchange Server email account added to my laptop’s Outlook account.

The reason this issue occurs is because your Microsoft email account file (typically a .OST file extension) is not set as the default data file. Your default is probably set to an archive .PST file, or in my case, my company of employment’s .OST file but not my client’s .OST file.

Hence, when I try to send an attachment from my client’s email – while I can change the email address I’m sending the email from (it defaults to my company of employment’s email address), the body of the message is not delivered when I hit the send button. It only works if I use my company of employment’s default email address.

To check if your email account is set as the default data file, open up Outlook and navigate to File > Account Settings > Account Settings > Data Files (tab). Ensure that the little black circle with a white check mark (default) is set to the correct .OST file for your exchange account. If it’s not, you need to set it to default by selecting the correct file in the list & clicking the “Set as Default” button.

Unfortunately for me – this means it will continue to work so long as I always use my email for my company of employment, if I want to send the email using my client’s email address, I have to manually save the file & attach to the email using other methods.

Hope this helps you if you are experiencing this issue!


Posted by: Yosef B. | April 12, 2016

Building Dynamically Driven Excel Hyperlinks

I recently came upon a challenge that at face value looked straight forward but actually proved to be quite tricky.

What I wanted to do was create a drop-down menu in Excel. Depending on the choice selected, a hyperlink would be created that would allow you to “jump” to a specific location in the Excel workbook based upon your selection.

The solution I hit upon is to use the Hyperlink formula with a unique twist.

First, I created two different worksheets – for this example I’ve creatively named them “Test Sheet 1” & “Test Sheet 2”.

Next, I created a drop-down list menu using the two worksheet names (cell C2 in picture below; see my previous post for details: Excel: Creating a Drop Down Menu).

Excel: Drop Down Menu Example

Excel: Drop Down Menu Example

Finally, in cell C4 I put the following formula =HYPERLINK("#'"&C2&"'!A1","Go to "&C2) where the first part "#'"&C2"'!A1" builds the actual link #’Test Sheet 1′!A1 or #’Test Sheet 2′!A1 (depending on the drop down selection) that takes you to the A1 cell on either the Test Sheet 1 or Test Sheet 2 worksheet, and the second half "Go to "&C2 builds the text that’s displayed to the user in cell C4.

Excel: Dynamic Hyperlink Formula

Excel: Dynamic Hyperlink Formula

Viola! Depending on the drop down item selected, the hyperlink will dynamically update and direct the user to the correct worksheet.

The tricky part was in figuring out where to put all the single & double quote marks as well as learning about using the hash mark to indicate that the URL was inside the current workbook without having to specify the full name of the workbook.

This should come in handy when building table of contents, forms, &/or surveys in Excel.


Posted by: Yosef B. | March 15, 2016

Windows 10 Calculator Shortcut

I’m used to pulling up the built-in Microsoft Windows calculator app when I have a quick calculation to do.
I recently discovered that with Windows 10 I don’t even need to open the calculator! I can simply open the start menu (Windows key) and start typing my math problem (including trig functions!) and it will display the answer right there in my start menu!

For all I know this has been available in Windows 8 for a while but I definitely use this tip now that I know about it!

Here’s a screenshot of what I mean – try it out yourself!

Windows 10 Start Calculator

Windows 10 Start Calculator

Posted by: Yosef B. | February 16, 2016

PSA: Use Microsoft Word to create & edit PDFs!

PSA! You no longer need a professional PDF editing program such as Adobe Acrobat to create & edit the majority of PDF files!

It has come to my attention that folks may not know about these features in Microsoft Word. The latest couple of versions of Microsoft Word have built in features to convert and create PDF files.

To open a PDF and convert it to an editable Word document, simply open the PDF file from inside Word.

  1. Open Microsoft Word
  2. Click the Open Other Documents link on the bottom left of the screen
  3. Browse to the folder location of the PDF file and select it
  4. Click the Open button
  5. Word will present you with a message that it will now try to convert the PDF file to an editable Word document. Depending on the size of the file, this may take a while. Select OK

That’s it! Word should create a new Word document that looks identical (or really close) to the PDF document. Depending on the PDF, it may treat text as text or as a picture – it depends on how the PDF was created and if the fonts are embedded in the document or not. In other words, your mileage may vary but in general this works quite well.

Once you’ve modified your Word document, you can save it directly from Word to a PDF document.

  1. Click on the File tab
  2. Select Save As from the menu on the left
  3. Browse to where you want to save the file
  4. Select PDF (*.pdf) from the Save as type drop down
  5. Click the Save button

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