Author Archives: Juan

Protecting Email Reputation

It is important to have a good email reputation, in order that your messages are not being marked as spam, and miss the recipient’s inbox. If you are using an email service, they will often provide you with recommended settings. For example, Google provides settings for SPF, DKIM, and DMARC. In addition to your usual email provider, it is also best to add records for other domains sending email on your behalf, such as mailchimp.

If your website is not actively being used for sending email. It is important to let the world know that any email they receive from your domain is being impersonated. In this case, you can set the appropriate records as recommended at CLOUDFLARE.

MacBook Does Not Recognize USB Drive

When upgrading from an older Mac, I needed to get some data off my old hard drives with the older USB connectors. Trying different USB-C to USB adapters, I noticed that there would be a pop up window that immediately disappeared, and then nothing happened.

It turns out nothing was wrong with the adapters, it was just the system dialog was disappearing too quickly. To fix this for yourself, you would need to go into the System Settings -> Privacy & Security and then scroll down to the Security section where you will see “Allow accessories to connect”.

Then click on the selections and choose either “Automatically When Unlocked” or “Always”.

I recommend “Automatically When Unlocked” so that you will have need to be logged into your desktop for the device to connect.

Securing your website with an SSL certificate

Securing your website with a SSL certificate has become more important. Google has decided this is an important factor in how websites are presented in Chrome.

There are several options for SSL certificates which range from free to thousands of dollars.

A free SSL certificate from Let’s Encrypt will give your site visitors confidence that their information is not leaking to the web when they interact with your site.

In addition to installing the certificate, I recommend redirecting all http traffic to your new https url. This is also a good time to choose a preferred domain, such as
https://computerwhisperer.com
as opposed to
https://www.computerwhisperer.com.

Create pdf thumbnails

This perl script uses ImageMagick to convert the first page of a directory structure of pdf’s into a 600 pixel wide png thumbnail.  The [0] in file.pdf[0] means to convert only the first page.

#!/usr/bin/perl -w
use strict;

my $tmp = `find . -iname '*.pdf'`;
print "$tmp\n";
my @files = split(/\n/, "$tmp");
foreach my $file (@files)
{
  my $outfile = "${file}.png";
  if (! -f $outfile)
  {
    my $command = "convert -thumbnail 600 '$file\[0\]' '$file.png'\n";
    print $command;
    `$command`
  }
  else
  {
    print "$outfile already exists\n";
  }
}

Screen Blanking on Linux Consoles

Linux consoles will blank after a few minutes. These are the screens which you get if you type ctrl-alt-f1 through ctrl-alt-f6 when you are logged into x-windows. To disable this behavior, type:

setterm -blank 0