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Wed, Jan 31, 2018 11:48 pm

Using olefile to obtain metadata from an OLE CDF V2 file

Microsoft's Object Linking and Embedding (OLE) technology allows embedding and linking to documents and other objects. OLE allows the addition of different kinds of data to a document from different applications, such as a text editor and an image editor. This creates a Compound File Binary Format (CFBF), aka a Compound File, Compound Document format, or Composite Document File V2 (CDF V2) document.

While using my MacBook Pro laptop, which is currently running the OS X El Capitan (10.11.6) operating system, I often need to extract embedded documents from an Excel .xlsm file. I do that by renaming the file to have a .zip rather than a .xlsm file extension. I can then extract the files contained within the .zip file just as I would any zip file. Within the directory structure created by unzipping the zip file there is an xl/embeddings subdirectory with .bin files within it.

$ ls xl/embeddings
Microsoft_Visio_Drawing1.vsdx	oleObject2.bin
Microsoft_Visio_Drawing2.vsdx	oleObject3.bin

[ More Info ]

[/languages/python] permanent link

Tue, Jan 30, 2018 11:22 pm

Using Python to extract data from a spreadsheet and put it in a database

I need to review spreadsheets related to work requests on a daily basis. The Excel workbooks have multiple worksheets within them. I have been manually copying data from specific cells in one of the worksheets and pasting it into a SQLite database. I use DB Browser for SQLite to paste the information into the database. I wanted to automate the process of extracting the data from the .xlsm or .xlsx workbook files and inserting it into the SQLite database using a Python script. So I initially created a script that I could run from a Teminal window on my MacBook Pro laptop, as noted in Extracting data from cells in an Excel workbook with Python, that would just print the information to the Terminal window's command-line interface. I had another script to import data from a text file into an SQLite database with Python, so I combined code from that script with the one to read data from the spreadsheets to add the data to a table in the database.

[ More Info ]

[/languages/python/excel] permanent link

Sun, Jan 28, 2018 10:15 pm

Reading specific lines from a file into another file within Vi

If you need to read lines from another file into the file you are currently editing within the Vi text editor, you can do so by utilizing the editor's ability to execute an external command, e.g., a Linux/Unix shell command, by entering an exclamation mark followed by the external command. E.g., if I wanted to read the first 55 lines from the file ~/temp/lincoln.txt, I could e nter Vi's colon mode by hitting Esc followed by the colon character. I could then type r, which is the command used to read from another file. But, instead of immediately typing the file name, e.g. :r ~/temp/lincoln.txt, I could use the head utility to read the first fifty-five lines of the file by typing head -55 followed by the path to the file and the file name. E.g.:

:r !head -55 ~/temp/lincoln.txt

If, instead, I wanted to read the last 14 lines of the file, I could use the tail command.

:r !tail -14 ~/temp/lincoln.txt

If I wanted to include specific lines from the other file into the one I'm currently editing, e.g., lines 10 through 15, I could use the sed command as shown below.

:r !sed -n 10,15p ~/temp/lincoln.txt

[ More Info ]

[/software/editors/vi] permanent link

Sat, Jan 27, 2018 6:50 pm

Turning on UltraVNC server service on a Windows system

If you installed UltraVNC, which is free and open-source software, to provide Virtual Network Computing (VNC) connectivity from/to a system for remote administration capabilities, but haven't enabled the UltraVNC server service to allow the system itself to be managed remotely, you can enable that service by taking the following steps:

  1. Run the uvnc_settings.exe program, which you can find in the directory where you installed UltraVNC. You will need to provide the login credentials for an account with administrator-level access on the system.
  2. Click on the Service tab then click on the Install Service button, which will install the software as a service, i.e. as a function provided by a server, on the system.
  3. Once the service is installed, you can click on the Start Service button to run the service.
  4. You can set the password to be used for VNC connections by clicking on the Security tab. You can set two passwords. The "VNC Password" will allow remote control of the system whereas the "View-Only Password" will only allow viewing the display on the system, which is helpful if you want to show someone what is happening on the system without giving the person the ability to control the system. You can then click on the OK button to close the UltraVNC settings window.

[ More Info ]

[/os/windows/software/remote-control/vnc/ultravnc] permanent link

Fri, Jan 26, 2018 10:51 pm

Extracting data from cells in an Excel workbook with Python

I've been using xlrd to extract a column from an Excel spreadsheet with a Python script on my MacBook Pro laptop. With xlrd, you can read data from cells in a workbook by specifying a specific sheet and the cells from which you wish to extract the data in spreadsheet programs, such as Microsoft Excel, Apache OpenOffice Calc, or LibreOffice Cale.

With spreadsheet applications you normally have rows sequenced by numbers and columns sequenced by alphabetical characters. With xlrd, though, both rows and columns are specified by numbers with the first row starting at 0 and the first column starting at 0 as well.

[ More Info ]

[/languages/python/excel] permanent link

Wed, Jan 24, 2018 10:39 pm

Determine NTP server on a Microsoft Windows system

If you wish to determine the Network Time Protocol (NTP) server that a Microsoft Windows system is using to synchronize its time, you can find that information in the Windows registry at HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\Parameters\NtpServer.


You can query that value from a command-line interface (CLI) with the command reg query HKLM\System\CurrentControlSet\Services\W32Time\Parameters. To see just the NTP server fully qualified domain name (FQDN), you can pipe the output of the reg query command to the find command and search for "NtpServer".

C:\>reg query HKLM\System\CurrentControlSet\Services\W32Time\Parameters

    NtpServer    REG_SZ,0x9
    ServiceDll    REG_EXPAND_SZ    %systemroot%\system32\w32time.dll
    ServiceDllUnloadOnStop    REG_DWORD    0x1
    ServiceMain    REG_SZ    SvchostEntry_W32Time
    Type    REG_SZ    NTP

C:\Users\Administrator.LABYRINTH>reg query HKLM\System\CurrentControlSet\Services\W32Time\Parameters | find "NtpServer"
    NtpServer    REG_SZ,0x9


In the above example, the time server is, an NTP server provided by Microsoft.

[/network/ntp] permanent link

Tue, Jan 23, 2018 9:42 pm

Using key pairs with SSH

The Secure Shell (SSH) protocol provides a means one can use for secure, encrypted connections between systems for logins or file transfers. One can use a username and password to login from an SSH client to an SSH server or one can use a public and private key combination where a public key for a user's account is stored on a remote SSH server while a corresponding private key is stored on the system from which the user will initiate the SSH or SFTP connection. On Linux systems, private keys are normally stored in the .ssh directory beneath the home directory for your account. If you haven't created any keys yet, the directory may only contain a known_hosts file that contains public keys for servers you've previously logged into via SSH.

[ More Info ]

[/network/ssh] permanent link

Mon, Jan 22, 2018 5:26 pm

This page intentionally left blank

Books and other documents may often include pages intentionally left blank stating "This page [is] intentionally left blank." As explained in the Wikipedia intentionally blank page article, this is often done due to the way pages are printed from a much larger sheet of paper or for legal reasons. On the web you can find an online equivalent in The This Page Intentionally Left Blank (TPILB) Project which notes:

In former times printed manuals had some blank pages, usually with the remark “this page intentionally left blank”. In most cases there had been technical reasons for that. Today almost all blank pages disappeared and if some still exist here and there, they present flatterly comments like “for your notes” instead of the real truth: This page intentionally left blank!

Nowadays the “This Page Intentionally Left Blank”-Project (TPILB-Project) tries to introduce these blank pages to the Web again. One reason is to keep alive the remembrance of these famous historical blank pages. But it is the primary reason to offer internet wanderers a place of quietness and simplicity on the overcrowded World Wide Web—a blank page for relaxing the restless mind.

Since I sometimes want to take browser screenshots that display options that are available in various browsers, but would prefer not to have any webpage content displayed in those screenshots, I've also created a "this page intentionally left blank" page.

[/network/web/design] permanent link

Sun, Jan 21, 2018 10:56 pm


OpenVPN is free and open-source software that provides Virtual Private Network (VPN) connectivity that is available for a variety of operating systems. To use the software on a Microsoft Windows 10 system, download the the installer for Windows Vista and later from the OpenVPN Community Downloads page; get the OpenVPN community software not the PrivateTunnel software from the OpenVPN project - I mistakenly downloaded and installed PrivateTunnel when I first went to the OpenVPN site and then had to uninstall PrivateTunnel.

[ More Info ]

[/os/windows/network/vpn] permanent link

Sat, Jan 20, 2018 11:01 pm

Updating Windows Subsystem for Linux

If you set up the Windows Subsystem for Linux on Windows 10, you may find that when you subsequently select Bash on Ubuntu on Windows to obtain a Bash shell prompt, that you see a message indicating that packages need to be updated. E.g.:

106 packages can be updated.
71 updates are security updates.

You can get the updates with apt-get update. You can then install the updates with apt-get upgrade. You may need to respond to a "Do you want to continue?" prompt. If there are a lot of updated packages to install, be prepared to wait awhile for the upgrade process to complete.

[ More Info ]

[/os/windows/win10/Linux-Subsystem] permanent link

Fri, Jan 19, 2018 8:21 pm

Windows 7 to 10 upgrade hung at "finalizing your settings"

A few days ago I upgraded a Windows 7 Professional system to Windows 10. After the upgrade was installed, I saw a blue screen with "Finalizing your setings" with a spinning circle of dots above it. I didn't need to use the system for a few days, so I left it in that state for about 3 days. But with the same message displayed today, I was able to resolve the problem today by holding the power button down for about 15 seconds until the system powered off. When I powered the system back on afterwards I saw "Welcome to Windows 10!" with the account I had been logged into before the upgrade showing and a Next button near the bottom, right-hand corner of the screen. When I clicked on Next, I saw the "Choose privacy settings for your device" screen, though I had made those selections during the upgrade process previously. I altered the selections again as I had before and then saw a "Meet Cortana" screen where I clicked on Not now. I then saw "Finalizing your settings" again briefly and then the screen went black. I saw the disk activity LED for the laptop blinking rapidly for a minute and then I saw a circle of spinning dots on a blue background above "Please wait", but then I got to the "Press Ctrl+Alt+Delete to unlock" screen and was able to log into the laptop where within a few moments I saw "Thank you for updating to the latest version of Windows 10. I typed winver in the Cortana "Ask me anything" field and hit Enter which resulted in winver being shown as the best match. When I selected it, I saw the current version of Windows being displayed as Windows 10 Version 1709 (OS Build 16299.125).

[/os/windows/win10] permanent link

Thu, Jan 18, 2018 11:55 pm

Viewing the login history for a user on a Linux or OS X system

If you want to see the IP addresses from which logins have occurred on a Linux or OS X system, you can use the last command. E.g.:

$ last ann
ann      tty2                          Thu Jan  5 20:23 - 20:27  (00:03)
ann      tty2                          Thu Jan  5 20:05 - 20:06  (00:00)
ann      tty2                          Thu Jan  5 20:01 - 20:02  (00:00)
ann      pts/0       Sun Oct 30 10:43 - 16:59  (06:16)
ann      pts/0      Tue Oct 11 12:02 - 12:03  (00:00)
ann      pts/0      Tue Oct 11 12:01 - 12:01  (00:00)
ann      pts/32      Sat Jun 11 20:03 - 20:38  (00:35)
ann      pts/32      Sat Jun 11 13:23 - 14:22  (00:58)
ann      pts/14      Sun Feb 14 17:05 - 18:28 (6+01:22)
ann      pts/6        Sun Nov  8 09:23 - 10:16  (00:52)
ann      pts/6        Sat Nov  7 08:54 - 16:42  (07:48)
ann      pts/7        Fri Nov  6 16:47 - 16:49  (00:02)
ann      pts/6        Fri Nov  6 15:48 - 23:33  (07:44)
ann      pts/0        :0               Thu Sep 10 15:25 - 12:38 (129+22:13)
ann      :0           :0               Thu Sep 10 15:24 - 12:38 (129+22:14)
ann      pts/5        :0               Sun Aug 23 11:08 - crash (18+04:03)
ann      pts/4        :0               Sat Aug 22 21:16 - crash (18+17:56)
ann      pts/3        :0               Sat Aug 22 09:14 - crash (19+05:58)
ann      :0           :0               Sat Aug 22 09:07 - crash (19+06:05)
ann      pts/2      Sun Jul 19 15:41 - 20:59 (1+05:18)
ann      pts/2      Mon Jun 22 21:28 - 20:17 (18+22:49)
ann      pts/2      Fri Feb  6 21:26 - 21:26  (00:00)
ann      pts/5      Wed Nov  5 21:07 - 22:15  (01:08)

wtmp begins Sun Oct  5 20:09:11 2014

[ More Info ]

[/os/unix/commands] permanent link

Wed, Jan 17, 2018 11:01 pm

Renewing a DHCP lease under OS X

If you wish to renew a Dynamic Host Configuration Protocol (DHCP) lease on a Mac OS X system, you can do so by clicking on the Apple icon in the upper, left-hand corner of the screen, selecting System Preferences, and then Network , and then the relevant network interface, e.g., Wi-Fi. Then click on the Advanced button and then the TCP/IP tab. You can then click on the Renew DHCP Lease button to have the system attempt to renew its DHCP lease.

[ More Info ]

[/os/os-x] permanent link

Tue, Jan 16, 2018 10:30 pm

Can't insert worksheet in Microsoft Excel for Mac 2016

When I tried to insert another worksheet in an Excel workbook today, I found that the option to insert a new blank worksheet was grayed out when I clicked on Insert and selected Sheet.

Excel 2016 - insert sheet grayed out

When I tried another means of adding a new sheet by clicking on the plus sign at the right side of the list of sheets in the worksheet to add the sheet, I saw an alert message stating "Workbook is protected and cannot be changed."

[ More Info ]

[/software/office] permanent link

Mon, Jan 15, 2018 7:37 pm

Using the Windows Resource Monitor to monitor network activity

If you want to see the IP addresses to which a program on a Microsoft Windows system is establishing connections, you can use the Resource Monitor utility that is provided with Windows Vista and later versions of Windows to check on network connections from a particular application on the system. To start the program, you can click on the Windows Start button and type resmon or resmon.exe in the "Search programs and files" field on a Windows 7 system or the "Type here to search" field on a Windows 10 system. You should see the resmon utility returned as the best match.

When the Resource Monitor program is running, you can click on the Network tab and then TCP Connections to see network activity associated with programs currently running on the system . You can click on a column header, e.g. "Image" to sort the entries by the values in that column.

[ More Info ]

[/os/windows/network/monitoring/resmon] permanent link

Sun, Jan 14, 2018 11:02 pm

Comodo OCSP

After I started the gVim text editor on a Windows laptop, I saw a "firewall alert" from the Symantec antivirus/firewall software on the system stating "Suspicious network activity has been detected." I've used gVim on many other systems for many years, but those systems weren't running the Symantec security software. The Symantec software showed that gvim.exe was attempting a Domain Name System (DNS) query to port 53, the well-known port for DNS, to IP address, the Google DNS server specified on the system for DNS queries.

[ More Info ]

[/network/ocsp] permanent link

Sat, Jan 13, 2018 10:20 pm

Using downloaded Visio stencils with Visio 2016

I needed to add a Juniper SRX Series Services Gateway to a network diagram created with Microsoft Visio 2016, so I downloaded the SRX Series stencils from Juniper Networks Product Icons & Visio Stencils page. The downloaded file was a ZIP file, so I extracted the contents of that file. Within the .zip file were two .VSS files: Juniper Branch SRX Series.vss and Juniper Data Center SRX Series.vss. On a Microsoft Windows system, if you wish to make shapes within a .vss file available within Visio, you can copy the .vss files to the My Shapes directory within the Documents directory for the account you are using. To then access the shapes, click on More Shapes on the left side of the Visio 2016 window, then select My Shapes. You should then see the names for the .vss files you added to the My Shapes directory listed.

[ More Info ]

[/os/windows/office/visio] permanent link

Fri, Jan 12, 2018 10:55 pm

Viewing only the files created today on a Linux system

I sometimes need to see only the files created or modified today in a directory. On a Linux system, you can pipe the output of the ls command into the grep command looking for just today's date in the input to the grep command as shown below:

$ ls -al --time-style=+%D ~/Documents/*.zip | grep $(date +%D)
-rw-r--r--. 1 joe joe   269338 01/12/18 /home/joe/Documents/

You can specify how the date is displayed with +format where format is a particular format in which you want the date displayed - see Formatting the output from the date command on a Linux system. If you use +%D, the date will be displayed as m/d/y, i.e., month/day/year, e.g. 01/12/18 for January 12, 2018. By then using the grep command to search for that value, you can limit the displayed files to only those created or modified today.

[ More Info ]

[/os/unix/commands] permanent link

Sat, Jan 06, 2018 5:01 pm

Configuring Sendmail to always allow Steam email

A family member wasn't receiving email for a Steam account she created to play a PC game. Her email comes through a Sendmail email server I manage and I found that a Domain Name System-based Blackhole List (DNSBL), the Spam and Open Relay Blocking System (SORBS), had blocked email from the IP address that Valve had for the email server used to send email to her about the account. When I checked the sendmail log file, I found the following two entries:

Dec 29 21:10:26 moonpoint sendmail[27413]: ruleset=check_relay, arg1=smtp03.stea, arg2=, [], rej
ect=550 5.7.1 Spam Block:mail from refused - see http://dnsbl.sorb
Dec 29 21:17:35 moonpoint sendmail[27661]: ruleset=check_relay, arg1=smtp01.stea, arg2=, [], rej
ect=550 5.7.1 Spam Block:mail from refused - see http://dnsbl.sorb

Checking, I found the following IP addresses and fully qualified domain names (FQDNs) for Steam email servers:

IP AddressFQDN

To ensure that none of the DNSBLs I use with Sendmail will ever block email from the Steam email servers, I added the following lines to /etc/mail/access:

Connect:                           OK
Connect:                           OK
Connect:                           OK
Connect:                           OK
Connect:                           OK

I then used the makemap hash command to rebuild the access database.

# makemap hash /etc/mail/access </etc/mail/access

Once I did that, she was able to receive the Steam-related email.

[/network/email/sendmail] permanent link

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