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Fri, Sep 29, 2017 11:04 pm

Extracting data from a corrupted zip file with jar or repairing it

I received a zip file containing data captured with tcpdump on a Linux system. When I tried to open the zip file on my MacBook Pro laptop running OS X El Capitan by double-clicking on the file within the Finder, I saw an "unable to expand" error message stating "Error 2 - No such file or directory." A Microsoft Windows user who downloaded the same zip file reported that he was unable to open it, either. When I tried to unzip the file from a Terminal window using the unzip utility, I saw an "End-of-central directory signature not found" error message.

$ file Zip archive data, at least v2.0 to extract
$ unzip 
  End-of-central-directory signature not found.  Either this file is not
  a zipfile, or it constitutes one disk of a multi-part archive.  In the
  latter case the central directory and zipfile comment will be found on
  the last disk(s) of this archive.
unzip:  cannot find zipfile directory in one of or, and cannot find, period.

[ More Info ]

[/software/utilities/file] permanent link

Tue, Sep 26, 2017 11:01 pm

Running the Chromium browser on a Linux system

Chromium is a free and open-source (FOSS) web browser that is very similar to the Google Chrome browser, though with some differences. Google started the Chromium project as a means to provide the source code for the proprietary Google Chrome browser. The Chromium Project is headed by Google developers with input from community developers.

If you wish to use the Chromium browser on a CentOS Linux system, you can install it by running the command yum install chromium from the root account. You can check if it is already installed on a CentOS system with rpm -qi chromium.

$ rpm -qi chromium
Name        : chromium
Version     : 60.0.3112.113
Release     : 2.el7
Architecture: x86_64
Install Date: Tue 26 Sep 2017 10:35:46 AM EDT
Group       : Unspecified
Size        : 106438445
License     : BSD and LGPLv2+ and ASL 2.0 and IJG and MIT and GPLv2+ and ISC and OpenSSL and (MPLv1.1 or GPLv2 or LGPLv2)
Signature   : RSA/SHA256, Tue 29 Aug 2017 08:00:23 AM EDT, Key ID 6a2faea2352c64e5
Source RPM  : chromium-60.0.3112.113-2.el7.src.rpm
Build Date  : Mon 28 Aug 2017 08:21:06 PM EDT
Build Host  :
Relocations : (not relocatable)
Packager    : Fedora Project
Vendor      : Fedora Project
URL         :
Summary     : A WebKit (Blink) powered web browser
Description :
Chromium is an open-source web browser, powered by WebKit (Blink).

[ More Info ]

[/network/web/browser/chromium] permanent link

Fri, Sep 22, 2017 11:18 pm

Failed POP3 login attempts from

While checking the mail log file, /var/log/maillog, on an email server today, I noticed an attempted login from an IP address in an address range I didn't recognize. The entry in the log file contained the following text:

dovecot: pop3-login: Disconnected (tried to use disallowed plaintext auth): user=<>, rip=

I checked the country associated with the IP address ( with geoiplookup (you can install the GeoIP package on a CentOS Linux system with yum install GeoIP) and found it was an address assigned to an entity in Great Britain.

$ geoiplookup
GeoIP Country Edition: GB, United Kingdom

[ More Info ]

[/security/attacks/pop3] permanent link

Mon, Sep 18, 2017 11:16 pm

Excel - This file is locked for editing

If you see an error message like the one below, which was produced by Microsoft Excel for Mac 2016 on a Mac OS X system, even though you don't have the file open currently, then you will need to delete the lock file, which should be in the same directory as the spreadsheet.

This file is locked for editing.

Locked by: John Doe
Filename: SGRS_2017.xlsm

You can open the file as read-only.


The lock file will have the same name as the workbook you were trying to open, but the file name will have ~$ prepended to it. To delete the file you will need to "escape" the meaning of the dollar sign by putting an escape character, i.e., a backslash character, immediately before the dollar sign. I.e., use ~\$ as shown below:

$ ls -alg **SGRS_2017.xlsm
-rw-rw-r--@ 1 ABC\Domain Users  761327 Sep 13 15:57 SGRS_2017.xlsm
-rw-rw-r--@ 1 ABC\Domain Users     171 Sep 18 22:46 ~$SGRS_2017.xlsm
$ rm ~$SGRS_2017.xlsm
rm: ~.xlsm: No such file or directory
$ rm ~\$SGRS_2017.xlsm

Once the lock file has been deleted, you should be able to open the file without the warning message that it is locked for editing.

[/software/office/excel] permanent link

Sun, Sep 17, 2017 11:09 pm

Determining the version of Microsoft Edge on a Windows system

You can obtain the version of the Microsoft Edge browser on a Windows system using the Get-AppXPackage cmdlet with Get-AppXPackage -Name Microsoft.MicrosoftEdge.

PS C:\> Get-AppXPackage -Name Microsoft.MicrosoftEdge

Name              : Microsoft.MicrosoftEdge
Publisher         : CN=Microsoft Corporation, O=Microsoft Corporation, L=Redmond, S=Washington, C=US
Architecture      : Neutral
ResourceId        :
Version           : 40.15063.0.0
PackageFullName   : Microsoft.MicrosoftEdge_40.15063.0.0_neutral__8wekyb3d8bbwe
InstallLocation   : C:\Windows\SystemApps\Microsoft.MicrosoftEdge_8wekyb3d8bbwe
IsFramework       : False
PackageFamilyName : Microsoft.MicrosoftEdge_8wekyb3d8bbwe
PublisherId       : 8wekyb3d8bbwe
IsResourcePackage : False
IsBundle          : False
IsDevelopmentMode : False
IsPartiallyStaged : False

PS C:\>

If you just want to see the version number and not the additional information, you can add "| select Version" at the end of the command.

PS C:\> Get-AppXPackage -Name Microsoft.MicrosoftEdge | select Version


PS C:\>

[/network/web/browser/edge] permanent link

Sat, Sep 16, 2017 11:05 pm

Determining the antivirus software on a Windows system from the command line

You can determine the antivirus software present on a system, if the antivirus software is registered with the Windows Security Center, using Windows Management Instrumentation Command-line (WMIC). E.g., for a Windows 10 system using Microsoft Windows Defender:

C:\>WMIC /Node:localhost /Namespace:\\root\SecurityCenter2 Path AntiVirusProduct Get displayName
Windows Defender


[ More Info ]

[/os/windows/commands/wmic] permanent link

Fri, Sep 15, 2017 11:04 pm

AskPartnerNetwork Directory on a Windows 10 system

A user reported her Windows 10 Professional system was running slowly. On September 14, 2017, I checked the system with SUPERAntispyware, which reported that it found the Ask Toolbar. It reported the following items associated with the toolbar:


[ More Info ]

[/security/scans] permanent link

Tue, Sep 12, 2017 10:58 pm

Adding an item to a list in Python without duplicates

If you have a list in a Python script and wish to add new items to the list, you can use listname.append(newitem) where listname is the name of the list and newitem is the item you wish to add to the list. If you wish to add new items to the list only if they don't already exist in the list, you can avoid adding an existing entry to the list by checking if the entry is already in the list as shown below:

filenameList = []
if filename not in filenameList:

If you wish to know the length of a list, i.e., how many items are on the list, you can use print len(listname) where listname is the name of your list.

[/languages/python] permanent link

Sat, Sep 09, 2017 11:53 pm

Backing up a MySQL or MariaDB table or database

You can backup a table in a MySQL or MariaDB database by using the mysqldump backup tool included with both database management systems. To backup a specific table you can use the command mysqldump database_name table_name where database_name is the name of the database that contains the table and table_name is the name of the particular table you wish to backup. E.g.:

mysqldump -u ptolemy -p Planets Mars > Mars.sql

In the above case, if I have a database named Planets with a table within it named Mars, I could backup just that one table from the database with the command above. The -u option to the command allows you to specify a MySQL/MariaDB username that has access to the database and the -p option will prompt you for the password associated with that username. The Mars.sql file will then contain all of the Structured Query Language (SQL) commands needed to recreate the table structure and the data in the table. E.g., it will contain insert SQL commands that will insert entries in the table.

[ More Info ]

[/software/database/mysql] permanent link

Fri, Sep 08, 2017 10:21 pm

Display a webpage from a Python script

If you just want to display text on a webpage from a Python script, a simple way to print to a web page is shown in the script below:


print "Content-type: text/plain\n"
print "Hello world"

If you want to display HTML code, you can use Python code like the following:


print "Content-type: text/html"
print """<!DOCTYPE HTML>
<html lang="en">
<h1>Hello World!</h1>

[ More Info ]

[/languages/python] permanent link

Thu, Sep 07, 2017 10:38 pm

Looping over a set of files in the Bash shell on Linux or OS X

I have a Python script,, that takes a file name as a parameter. I use the script to identify if a file with a .bin extension is actually a Microsoft Visio or PowerPoint file. I run the script on an OS X system from a Terminal window where I have a Bash shell prompt. E.g.:

$ ~/Documents/bin/ oleObject1.bin
Microsoft Office PowerPoint

But I often want to have it check all of the .bin files in a directory. You can loop through all files in a directory or a set of files using a Bash for loop. E.g., to check all of the .bin files in a directory I could use the for-loop below:

$ ls *
oleObject1.bin	oleObject3.bin	oleObject5.bin
oleObject2.bin	oleObject4.bin	oleObject6.bin
$ for f in *.bin; do ~/Documents/bin/ $f; done
Microsoft Office PowerPoint
Microsoft Office PowerPoint
Microsoft Office PowerPoint
Microsoft Visio
Microsoft Visio
oleObject6.bin: CDF V2 Document, No summary info


[ More Info ]

[/os/unix/bash] permanent link

Wed, Sep 06, 2017 11:57 pm

GoDaddy continues to show "Loading..." when composing email

Someone who uses GoDaddy for her email reported to me today that she couldn't send email. I logged into her account from another system and was able to send email to myself. When I notified her that I had been able to send email from her acount to myself, she sent an email to me, but reported it was still stating "loading" when she hit the send button. So tonight I logged into her system and opened the Firefox browser, since she uses that browser to send and receive email. When I clicked on Compose, I saw a "Loading..." message in the body of the email that wouldn't go away unless I clicked on the Plain Text tab to switch from "Rich Text", which allows one to format text in the message with bolding, font colors, etc., to "Plain Text". But when I switched back to "Rich Text", I had problems typing my email address in the "To" field with only one letter appearing in the "To" field no matter how many letters I typed.

[ More Info ]

[/network/email/godaddy] permanent link

Tue, Sep 05, 2017 10:55 pm

Using the PowerShell Get-WmiObject cmdlet to get BIOS information

You can get BIOS information on a system running the Microsoft Windows operating system using the PowerShell cmdlet Get-WmiObject cmdlet. E.g.

PS C:\> Get-WmiObject win32_bios

Manufacturer      : Award Software International, Inc.
Name              : Award Modular BIOS v6.00PG
SerialNumber      :
Version           : GBT    - 42302e31

PS C:\>

[ More Info ]

[/os/windows/PowerShell] permanent link

Mon, Sep 04, 2017 10:42 pm

Obtaining monitor information from a PowerShell Prompt

If you need to know information about the manufacturer and model number of a monitor on a Microsoft Windows system, you may be able to obtain it from a PowerShell prompt using the Get-WmiObject cmdlet as shown below:

PS C:\> Get-WmiObject win32_desktopmonitor

DeviceID            : DesktopMonitor1
DisplayType         :
MonitorManufacturer : HP
Name                : HP S2031 Series Wide LCD Monitor
ScreenHeight        :
ScreenWidth         :

PS C:\>

[ More Info ]

[/os/windows/PowerShell] permanent link

Sun, Sep 03, 2017 10:36 pm

SORBS blocking email from AOL

I manage a Linux server that functions as an email server using the free and open source software (FOSS) package sendmail. I provide a mechanism through the server for someone who has Verizon as his Internet Service Provider (ISP) to send monthly newsletters by email to an organization that has about thirteen hundred members on its email distribution list, since he can't send to that number of people through his ISP-provided email service. I do so by providing an email alias on my server, e.g., that he puts in the BCC line of his email. The alias is stored in /etc/aliases and points to a text file containing the list of all members' email addresses. So his ISP-provided SMTP server sees only the one address,, which results in an email message to the server I manage that then translates that address into the approximately 1,300 email addresses of members and sends the newsletter to all members.

But this month the user reported he had sent the message, but it had not been delivered to recipients. I first checked the server's mail log, /var/log/maillog, for any occurrences of his email address for the day he reported the problem. I use several free DNS-based Blackhole List (DNSBL) services to reduce the amount of spam that reaches user's inboxes, so I suspected that one of those services had blocked email from the SMTP server through which he was sending his message, even though I had whitelisted his email address quite some time ago by adding a line like the following one to /etc/mail/access and then running the command makemap hash /etc/mail/access </etc/mail/access.	OK

I didn't find any references to his email address in the /var/log/mail file, so I asked him to resend the message. I still didn't see any references to his email address in the /var/log/maillog file, but I did see that SORBS had blocked email from an America Online (AOL) server at the time he sent the message.

[ More Info ]

[/network/email/spam/sorbs] permanent link

Sat, Sep 02, 2017 10:14 pm

Task management with Taskwarrior

I wanted a simple easy to use application for managing my todo list that was free and open source software (FOSS) which I could install on Linux systems, but which might also be available for other operating systems as well. There are online, commercial alternatives, but I wanted something I could put on my own systems with no fear that my data might disappear should a commercial entity not remain commercially viable. I found Taskwarrior, an open-source, cross platform time and task management tool with a command-line interface (CLI). The command line interface is helpful to me since I'm often working on systems via a Secure Shell (SSH) connection and would like to be able to add to my task list on those systems without using a graphical user interface (GUI).

I wanted to first install it on a CentOS Linux system. It isn't in the default software repositories for CentOS, but if you configure a CentOS system to use the EPEL repository, you can easily install the Taskwarrior package using yum with yum install task.

[ More Info ]

[/software/projmgmt] permanent link

Fri, Sep 01, 2017 11:06 pm

PowerShell Get-Printer Cmdlet

If you want to know what options you have for printing files on a Microsoft Windows system, e.g., perhaps you want a list of currently avaialble printers or even want to know the IP addresses by which some printers are accessible, the PowerShell Get-Printer cmdlet may provide the information you are seeking. E.g.:

PS C:\Users\Pam> Get-Printer

Name                           ComputerName    Type         DriverName                PortName        Shared   Published
----                           ------------    ----         ----------                --------        ------   ---------
Microsoft XPS Document Writ...                 Local        Remote Desktop Easy Print TS002           False    False
Send To OneNote 2013 (redir...                 Local        Remote Desktop Easy Print TS003           False    False
Quicken PDF Printer (redire...                 Local        Remote Desktop Easy Print TS001           False    False
Send To OneNote 2010                           Local        Send To Microsoft OneN... nul:            False    False
Ricoh Aficio MP C2500 PCL5c                    Local        Ricoh Aficio MP C2500 ...    True     False
Microsoft XPS Document Writer                  Local        Microsoft XPS Document... PORTPROMPT:     False    False
Microsoft Print to PDF                         Local        Microsoft Print To PDF    PORTPROMPT:     False    False
HP Deskjet 6940 series                         Local        HP Deskjet 6940 series     True     False
Fax                                            Local        Microsoft Shared Fax D... SHRFAX:         False    False
Adobe PDF                                      Local        Adobe PDF Converter       Documents\*.pdf False    False
ABS PDF Driver v400                            Local        Amyuni Document Conver... LPT1:           False    False

PS C:\Users\Pam>

[ More Info ]

[/os/windows/PowerShell] permanent link

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