Archive for the ‘Computers’ Category

Notes on creating a droplet

Wednesday, January 17th, 2018

I created a new Digital Ocean droplet and mostly followed the tutorials to get things up and running. A couple of things that I need to do to get the environment the way it is on other machines.

I had a bit of trouble with using Public Key Authorization. I think that I was selecting the key by triple clicking until everything was highlighted and then copying. I believe that I got a line feed a the end of the key that was messing up my login attempts. Carefully highlighting just the key seems to have done the trick.

I also was stymied for a while when my site didn’t display. First, since I turned on the firewall I needed to add either www (sudo ufw allow www) or Apache (sudo ufw allow Apache) to the rules. And then verify with sudo ufw status.

When I created the droplet, I destroyed the previous one so I needed to find the DNS records and change the IP address. Unlike other services, DO puts that in Networking.

I need to copy my .bash_profile file over to my home directory and add the line
. ~/.bash_profile to my .profile file.

Reload the profile with source ~/.profile

I also want all of the files in the www directory to be created with the admin group. That way, no matter who created them, I’ll be able to edit them.

You can change the default group for all files created in a particular directory by setting the setgid flag on the directory (chmod g+s _dir_). New files in the directory will then be created with the group of the directory (set using chgrp <group> <dir>). This applies to any program that creates files in the directory. mark4o

The default location for web files is /var/www, which is different than the setup on my older machines. (probably because the default location varies across distributions and over time). I put a symlink to it in the root. sudo ln -s /var/www/ www

I don’t want people to be able to view the directories, especially the images directory, so I disabled that ability by removing the word Indexes from the option line.


Options Indexes FollowSymLinks
AllowOverride None
Require all granted

I covered this in earlier posts, but it doesn’t hurt to repeat it. I make a few modifications to the apache config file to keep people from seeing things on the server. I added these lines after the section on .htaccess.


# We don't want people to see .inc files
<Files  ~ "\.inc$">
  Order allow,deny
  Deny from all
</Files>

# Do not allow .git version control files to be viewed
<Directorymatch "^/.*/\.git+/">
  Order deny,allow
  Deny from all
</Directorymatch>

# We don't want people to see .svn files, mainly in Wordpress installs
<Directorymatch "^/.*/\.svn+/">
  Order deny,allow
  Deny from all
</Directorymatch>

On my older servers I have lots of sites and their names end in .com, .net, etc. but on this version of Apache, the a2ensite requires files to end in .conf.

I also had some trouble with the https code that was added to the site by certbot. I took them out after reviewing the output of sudo journalctl -xe.

To install the certbot certificate I went to the page for my setup and followed the directions. I have a .com and .org version of this site and allow access using www and without so I need the certificate to work for all four of these. Rather than getting four certificates, I got one for the name I will use most, the .org, and then added the ones for www and .com.

Unfortunately, at the moment there is a security vulnerability so the normal method does not work.

Instead I had to stop Apache and run


sudo certbot --authenticator webroot --webroot-path /var/www/ACOV/ --installer apache2 -d example.org

sudo certbot certonly --cert-name example.org -d example.com,www.example.org,www.example.com

service apache2 restart

I had some problems at first because I had not set up the DNS records at Digital Ocean correctly. I typed the whole domain into the add a record field, when I should have just typed www. It added www.example.com.examp instead of www.example.org. After I fixed that it created the certificates and I checked them.

Unfortunately, something else is not right because Apache is not serving up the SSL connection. I’ll update the post when I figure it out.

Running out of space.

Monday, January 8th, 2018

A server that I administer from time to time has been running out of space. I manually deleted all of the logs and freed up a ton of space. I turns out that there are lots of wget calls on this server and as more customers were added the number of lines in the Apache logs increased tremendously.

The access log was rotated weekly but it gets to be very large and on an old machine with only 70GB total, it adds up. I changed the log rotation in /etc/logrotate.d/apache2 to daily from weekly and keep them for 1 day instead of 26 weeks. The free space has remained at 10% since I made the change.


/var/log/apache2/*.log {
        daily
  missingok
  rotate 1
  compress
  delaycompress
  notifempty
  create 640 root adm
  sharedscripts
  postrotate
    if [ -f "`. /etc/apache2/envvars ; echo ${APACHE_PID_FILE:-/var/run/apache2.pid}`" ]; then
      /etc/init.d/apache2 reload > /dev/null
    fi
  endscript
}

Remove Password on PDF file.

Tuesday, March 14th, 2017

My accountant sent me my tax returns as password protected PDF files. There isn’t any way to get them out of Adobe Acrobat Reader without the password. There are lots of on-line solutions, but that means giving someone else access to your data. There are also programs that you can download, but it’s hard to know if you can trust them. Instead just drop your PDF onto Safari. Enter the password, then use File –> Print to print to PDF.

If you want to add a new password, open the file in Preview and then use the Export as PDF command. Click on the Show Details button and check the box for encryption. You can add your own password here. The encrypted files will open in Reader and Preview.

More Re-negotiation error in Apache logs

Friday, May 27th, 2016

I was worried that updating my page to only accept secure https connections might lock out some customers who are still using Windows XP and old IE browsers. I was a bit worried when,
after updating my SSL ciphers I am still getting errors like this:


SSL Library Error: error:14080152:SSL routines:SSL3_ACCEPT:unsafe legacy renegotiation disabled
[client 180.76.15.31:51166] AH02225: Re-negotiation request failed
[client 134.249.131.0:51259] AH02225: Re-negotiation request failed
[client 134.249.131.0:51123] AH02225: Re-negotiation request failed
[client 1.39.57.169:37633] AH02225: Re-negotiation request failed

However, looking up the first ip with whois yields a netname of Baidu, the next two are located in the Ukraine, and one from India. There are a whole bunch of these, so I’m guessing it’s some spammers looking for forms that they can fill in with links. I just had 643 catalog requests a few days ago that defeated my rudimentary spam checking tool, so that’s what I’m going with for now.

Re-negotiation error in Apache logs

Monday, May 23rd, 2016

After refactoring a site and implementing https for all pages on it, I started looking closely at the logs. I was getting lots of error messages with things like, ‘routines:SSL3_ACCEPT:unsafe legacy renegotiation’ and ‘Re-negotiation failed’, so I started looking into it. I was also vaguely aware of BEAST and RC4 weaknesses so I wanted to secure the Apache server as much as possible as well.

The first thing I found was a reference to the Mozilla Server Side TLS Config Generator. It gives a very long list of ciphers that are appropriate for your web server and client needs.

It also suggests using mod_headers to implement HSTS, which according to Wikipedia, “HTTP Strict Transport Security (HSTS) is a web security policy mechanism which helps to protect websites against protocol downgrade attacks and cookie hijacking.”

I didn’t see headers in my mods-available list and looking at the output of phpinfo();, it does not appear to have been implemented. To install mod_headers on Ubuntu you just need to run a simple command.


sudo a2enmod headers
sudo service apache2 restart

Now my mods look like this:
Apache mods

My old SSLCipherSuite was very short,
SSLCipherSuite ALL:!ADH:RC4+RSA:+HIGH:+MEDIUM:!SSLv2:+EXP:+eNULL
The new one is a monster


SSLCipherSuite          ECDHE-ECDSA-CHACHA20-POLY1305:ECDHE-RSA-CHACHA20-POLY1305:ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384:DHE-RSA-AES128-GCM-SHA256:DHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-AES128-SHA256:ECDHE-RSA-AES128-SHA256:ECDHE-ECDSA-AES128-SHA:ECDHE-RSA-AES256-SHA384:ECDHE-RSA-AES128-SHA:ECDHE-ECDSA-AES256-SHA384:ECDHE-ECDSA-AES256-SHA:ECDHE-RSA-AES256-SHA:DHE-RSA-AES128-SHA256:DHE-RSA-AES128-SHA:DHE-RSA-AES256-SHA256:DHE-RSA-AES256-SHA:ECDHE-ECDSA-DES-CBC3-SHA:ECDHE-RSA-DES-CBC3-SHA:EDH-RSA-DES-CBC3-SHA:AES128-GCM-SHA256:AES256-GCM-SHA384:AES128-SHA256:AES256-SHA256:AES128-SHA:AES256-SHA:DES-CBC3-SHA:!DSS

I have no idea what most of these are, but I’m sure the good folks at Mozilla do.

The last thing they recommend is that you implement OCSP Stapling. The details are complicated, but it basically speeds up the verification of the certificate.

After adding the new lines in the appropriate place in my sites-available file for the site, I restarted Apache and everything is running fine. In the fifteen minutes it took to write this up, I have had no negotiation messages in the error log.

Once you have implemented the changes, test your site at SSLabs. I got an A+.

Well Golly


Atheism Plus

Buy from Amazon