Linux Evolution Email broken/fails with Dovecot upgrade to Version 2.3

2019-0320. My Evolution email client stopped stopped working after my server upgraded Dovecot was from version 2.2 to 2.3. I was getting TLS errors in Evolution. The error was “The reported error was “Failed to get capabilities: Error performing TLS handshake: An unexpected TLS packet was received.” I also have Roundcube webmail based email and it continued to work. The fix to the problem was not hard (Thank you Linux Community) however there is not much information on the internet now on solving this problem and thus the reason I felt motivated to write this post and give back to the Linux community.

My server is Debian Sid (Buster/Debian 10). My email is setup using the guide from https://workaround.org/ispmail/stretch.

The solution to the problem is change the ssl configuration in the dovecot file “/etc/dovecot/conf.d/10-ssl.conf”. I also increased the security of the SSL/TLS protocols used. References are: https://wiki2.dovecot.org/Upgrading/2.3 and https://wiki2.dovecot.org/SSL/DovecotConfiguration.

I first needed to create a new Diffie Hellman parameters file that is involved in the TLS key exchange. This file collects entropy from the computer and took roughly an hour on my slow server computer. Enter these commands in the terminal. https://wiki2.dovecot.org/SSL/DovecotConfiguration#SSL_security_settings

cd /etc/dovecot
openssl dhparam 4096 > dh.pem

I removed the following lines in file “/etc/dovecot/conf.d/10-ssl.conf”.

ssl_protocols = !SSLv2 !SSLv3

I added and modified the following lines in file “/etc/dovecot/conf.d/10-ssl.conf”.

ssl_dh =</etc/dovecot/dh.pem
ssl_min_protocol = TLSv1.2
ssl_cipher_list = ALL:!DH:!kRSA:!SRP:!kDHd:!DSS:!aNULL:!eNULL:!EXPORT:!DES:!3DES:!MD5:!PSK:!RC4:!ADH:!LOW@STRENGTH
ssl_prefer_server_ciphers = yes

Restart the dovecot service

sudo systemctl restart dovecot

Check that the dovecot service is running

sudo systemctl status dovecot

All done and Evolution email is working.

Nextcloud 14.04 broken with upgrade to php7.3 in Debian testing/sid

Nextcloud 14.04 stopped working on me. I was getting a blank page on my nextcloud website. I found the following error message in my nextcloud logfile:

"Error: Call to undefined function OC\\App\\simplexml_load_file() at \/var\/www\/cc.com\/nextcloud\/lib\/private\/App\/InfoParser.php#64".

It appears the problem was when php was updated from 7.2 to 7.3 however the apache2 webserver was trying to use the older php7.2 module and php7.3 module was not enabled. The solution is to disable the php7.2 and enable php7.3 module for apache2. The following commands are entered into the terminal.

Disable the apache2 module php7.2

sudo a2dismod php7.2

Enable the apache2 module php7.3

sudo a2enmod php7.3

Restart the Apache webserver and show it’s running status

sudo systemctl restart apache2 & sudo systemctl status apache2

I found the following site helpful: https://tecadmin.net/switch-between-multiple-php-version-on-debian/

The server was Debian testing/sid. 2019-0110


Mythtv update trouble shooting for database username, hostname, and password

My mythtv was failing on an update for “no password” for “root” user. I needed to find out what values the update script was using for the database username, hostname, and password. This link had a script listed to show these values. I will repeat the script below.

Put the following in a file, mark it as executable and run it.  This will print the variables the mythtv-database upgrade script is using.

#!/bin/sh -e
/usr/share/debconf/confmodule
db_get mythtv/mysql_admin_user
admin_username=”$RET”
db_get mythtv/mysql_admin_password
admin_password=”$RET”
db_get mythtv/mysql_host
hostname=”$RET”
if test -z “$hostname”; then
hostname=localhost
fi
db_get mythtv/mysql_mythtv_dbname
database=”$RET”
echo “MythTV database upgrade variables (Debian):”
echo ” Username: $admin_username”
echo ” Password: $admin_password”
echo ” Hostname: $hostname”
echo ” Database: $database”

 

Certbot and Let’s Encrypt errors on creating a certificate

I was having failures creating new certificates in certbot due to a change in their code. I previously ran the following command to create a website certificate for an apache server running on Debian 8 Jessie.

# certbot run --verbose --text --apache --rsa-key-size 4096 --email your-email.com --agree-tos -d your-domain-name.com,alternative-domain-name.org,third-domain-name.com

This used to work but now (2018-0226) it doesn’t. Here is the output of error:

Performing the following challenges: 
Client with the currently selected authenticator does not support any combination of challenges that will satisfy the CA.
Exiting abnormally:
Traceback (most recent call last):
 File "/usr/bin/certbot", line 11, in <module>
 load_entry_point('certbot==0.10.2', 'console_scripts', 'certbot')()

I found the answer here: https://github.com/certbot/certbot/issues/5405

The following command worked, substitute working values for “your-email.com” and “your-domain-name.com”.

# certbot certonly --standalone --verbose --text --rsa-key-size 4096 --email your-email.com --agree-tos -d your-domain-name.com --pre-hook "systemctl stop apache2" --post-hook "systemctl start apache2"

This is for the following version of certbot.

# certbot --version
certbot 0.10.2

The end 🙂

Add SSL Certificate to Postfix and Dovecot with Let’s Encrypt

I am running a Debian 8 Jessie email server with postfix and dovecot. I wanted to change from self signed certificates to certificates from Let’s Encrypt. It was easy to do and I wish had not waited so long to change. This blog post, https://www.shivering-isles.com/lets-encrypt-free-trusted-certificates-for-postfix-and-dovecot/ explained it perfectly for me, so there is no need for me to document the commands.

https://letsencrypt.org/

Nextcloud 12 Internal Server Errors after Login

When I upgraded from owncloud 9 to Nextcloud 11, my web interface was broken and I could not login to Nextcloud with the web interface. I was able to sync files to the server. I then upgraded to Nextcloud 12 through the command line interface. I still could not login to the web interface. The cause of the problem was that I moved the location of the webserver files from /var/www/owncloud to /var/www/nextcloud. I made the appropriate changes to my apache “sites-enabled” configuration file to redirect to the new location at /var/www/nextcloud. I was recieving “Internal Server” errors and the web interface was broken and unusable. I fixed the problem by following this thread https://help.nextcloud.com/t/solved-nc12-internal-server-error-after-login/13256 on deleting the data the in the database table oc_filecache. My steps were to:

  1. stop the apache2 webserver
  2. delete everything in “oc_filecache”
  3. restart the webserver

I used phpmyadmin to remove the contents from “oc_filecache”. I think “oc_filecache” contained information pointing to the old location of my files in the owncloud directory instead of the new nextcloud directory. Below are the steps to delete the information in “oc_filecache”.

  1. Login to phpmyadmin.
  2. Select your “nextcloud” database. Your database may have a different name that “nextcloud”
  3. Select the table “oc_filecache” listed on the far left of the page
  4. Select “Operations” from the tab at the top of the page.
  5. Select “Empty the table (TRUNCATE)”
  6. Select “Ok” to confirm you will be deleting the data in “oc_filecache”.
  7. Finished.

Rotate your Rsync Backups with rotate-backups, similar to Time Machine

I use rsync on gnome-ubuntu 15.10 to back up my data to my server running Debian 8. This creates incremental backups similar to Apples Time Machine. The backup runs every 2 hours so this creates more backups than needed at the expense of hard drive space. I used to manually delete the files from the server and would try to save a monthly backup, 8 weekly backups, 30 daily backups, and 2 weeks of every 2 hour backups. This was a time consuming process of manually selecting the files and thus I was not consistent about removing the extra backups. My backup scripts are written in python and I was going to write a script that would delete old backups that were not needed any more. Even better than writing your own script is finding one that has already been written such as https://rotate-backups.readthedocs.org/en/latest/#rotate-backups-simple-command-line-interface-for-backup-rotation. This script will automatically delete your old backups and you can configure it for many backups you want to keep.

This script is well documented and easy to use. I give it my highest recommendation.

Rename File with Current Date in Debian 8 Linux

I had a need to rename a file with the current date after running a backup script. This was done on Debian 8 Linux. The backup script would make a file name called “/mnt/backup.chadchenault.com/backup/server.cc.com.webmin/webmin.tar.gz“. I like my backup files with year-month-day at the front of the filename for easy sorting by date. My format is 2016-0422 for the date of April 04, 2016. I am using the date command to insert the current date and this is command that runs automatically after the backup command is run.

mv /mnt/backup.chadchenault.com/backup/server.cc.com.webmin/webmin.tar.gz /mnt/backup.chadchenault.com/backup/server.cc.com.webmin/$(date “+%Y-%m%d.webmin.tar.gz”)

This results in a new filename of “/mnt/backup.chadchenault.com/backup/server.cc.com.webmin/2016-0422.webmin.tar.gz

Here are an example of testing the date command from the command line.

Create a file “delete.txt”

touch delete.txt

Copy the file to a new name with current Year-MonthDay.delete.txt format

cp -v delete.txt /root/$(date “+%Y-%m%d.delete.txt”)

The output of the command on 2016-0422 was:

‘delete.txt’ -> ‘/root/2016-0422.delete.txt’

The command was run successfully.

 

MythTV Hardware Video Accleration with VDAPU

OS: Mythubuntu 14.04
Hardware: AMD E-350 APU, 8 GB DDR3 1066,AMD Radeon HD 6310 graphics

Playback of video was choppy and CPU utilization would reach 100% without hardware acceleration. I am using default radeon open source video drivers. I installed VDPAU drivers with

 sudo apt-get install mesa-vdpau-drivers
Enable VDPAU through the MythTV frontend settings:
“Utilities -> Setup -> TV Settings -> Playback -> Playback Profiles (3/8)”
I selected “VDPAU High Quality”

Reference

https://www.mythtv.org/wiki/VDPAU