Creating a single SSL certificate bundle from CA root and intermediate certificates

When you purchase an SSL certificate for a domain, e.g. to secure HTTPS usage with your web server, your certificate download may provide you several files like this:

youdomain.com.crt : this is your domain certificate

Files that look this are the root and intermediate certificates:

USERTrust_RSA_Certification_Authority.crt

Sectigo_RSA_Domain_Validation_Secure_Server_CA.crt

Depending how your SSL vendor supplies these files, the second two files may be provided already bundled in one file or two separate files.

To combine them together into one bundle file, use cat to concat the files:

cat yourdomain_com.crt USERTrustRSAAddTrustCA.crt AddTrustExternalCARoot.crt > domain_com.ca-bundle.crt

Open the file and check that each start and end comment for each cert are on their own line and not on the same line (see here).

Increasing media upload size for WordPress / PHP5

On a default WordPress 4.8 install on PHP5 the default file upload size seems to be (at least on my install) 2MB. If you’re uploading large image files or videos, it’s likely you’ll want to upload files much larger than this.

There’s a number of possible configuration locations that can control/configure the upload size. The first location is likely to be your php.ini file used by your apache or nginx. The settings to increase are:

  • post_max_size (must be larger than upload_max_size)
  • upload_max_filesize
  • memory_limit

This article has a comprehensive walkthrough the possible configuration changes.

Reducing memory usage by Apache and MySql in a 512MB VPS

Installing with the default Apache and MySQL configurations, you end up with far too many idle Apache threads, and MySQL is the largest memory user by far. The default config of these two is maxing out my available 512MB in my VPS server:

/etc/apache2$ ps -eo pmem,pcpu,rss,vsize,args | sort -k 1 -r       

%MEM %CPU   RSS    VSZ COMMAND
 9.5  0.0 49904 720256 /usr/sbin/mysqld
 6.7  0.0 35620 286860 /usr/sbin/apache2 -k start
 6.5  0.0 34452 283524 /usr/sbin/apache2 -k start
 6.2  0.0 32692 283012 /usr/sbin/apache2 -k start
 5.9  0.0 31276 283116 /usr/sbin/apache2 -k start
 5.8  0.0 30896 282652 /usr/sbin/apache2 -k start
 5.0  0.0 26724 282588 /usr/sbin/apache2 -k start
 4.8  0.0 25204 279552 /usr/sbin/apache2 -k start
 4.8  0.0 25200 279552 /usr/sbin/apache2 -k start
 4.7  0.0 25156 279508 /usr/sbin/apache2 -k start
 4.4  0.0 23216 279540 /usr/sbin/apache2 -k start
 2.8  0.0 15136 278400 /usr/sbin/apache2 -k start
 0.7  0.0  3968  90908 sshd: myuser [priv] 
 0.4  0.0  2564  61312 /usr/sbin/sshd -D
 0.4  0.0  2264  33188 init
 0.3  0.0  2060  18128 -bash
...

/etc/apache2$ free
             total       used       free     shared    buffers     cached
Mem:        524288     476496      47792      68220          0     260764
-/+ buffers/cache:     215732     308556
Swap:            0          0          0

 

From tips in this article, I reduced down the Apache threads and now we’re at:

/etc/apache2/mods-enabled$ ps -eo pmem,pcpu,rss,vsize,args | sort -k 1 -r
%MEM %CPU   RSS    VSZ COMMAND
 9.5  0.0 49904 720256 /usr/sbin/mysqld
 2.8  0.0 15132 278400 /usr/sbin/apache2 -k start
 1.1  0.0  6004 278424 /usr/sbin/apache2 -k start
 0.7  0.0  3968  90908 sshd: myuser [priv] 
 0.4  0.0  2564  61312 /usr/sbin/sshd -D
 0.4  0.0  2264  33188 init
 0.3  0.0  2076  18136 -bash

/etc/apache2/mods-enabled$ free
             total       used       free     shared    buffers     cached
Mem:        524288     400244     124044      68220          0     262480
-/+ buffers/cache:     137764     386524
Swap:            0          0          0

Now we’ve got some free space, and definitely not maxing out our available ram. Next up, I’ll take a look at MySQL.