LinuxHostingSupport

For a plain Linux server, follow: How to install APC cache on a Linux server?

Installation of APC cache on a cPanel server is pretty easy. Follow the below steps to install APC cache on cPanel server:

1. SSH to the server and execute:

# yum install pcre-devel

2. Goto WHM –> PHP Configuration Editor –> Advanced Mode, change the  “extension_dir” value from

/usr/local/lib/php/extensions/no-debug-non-zts-20060613
to
/usr/lib/php/extensions/no-debug-non-zts-20060613

3. Install APC cache from WHM.

WHM --> Module Installers --> click Manage next to "PHP Pecl".
Search APC and install it.

4. Change PHP Handler to DSO. You can either do this from WHM OR via SSH:

WHM --> Service Configuration --> Apache Configuration -->
Configure PHP and SuExec --> PHP5 Handler
OR
# /usr/local/cpanel/bin/rebuild_phpconf 5 0 dso 1

Once done, make sure apc.so file is present in the /usr/lib/php/extensions/no-debug-non-zts-20060613 directory. Sometimes it is created in the original directory and you have to create a symlink.

# ln -s /usr/local/lib/php/extensions/no-debug-non-zts-20060613/apc.so \
 /usr/lib/php/extensions/no-debug-non-zts-20060613/apc.so

Restart the Apache webserver and to confirm if APC is activated, execute:

# php -i | grep apc

cPanel, WHM and even Webmail uses non-common ports which some Internet Server Providers (ISP) do not allow and makes it impossible for people to access any of these. cPanel works on 2082/2083, WHM 2086/2087 and Webmail 2095/2096.

The workaround is to install cPanel Proxy which works as a proxy gateway for Apache and the requests to cPanel/WHM/Webmail are then served through port 80 instead of their respective ports which are blocked by the ISP.

Here’s how to Install cPanel Proxy:
——————————————————————————–
1. You have to recompile Apache with the cPanel proxy module.
a) You can either execute ‘/scripts/easyapache‘ script via SSH
OR
use WHM -> Software -> ‘EasyApache (Apache Update)‘ option.

b) On the next step, leave the current profile as it is and click ‘Start Customizing Based on Profile’

c) Click ‘Next Step’ in the Apache/PHP selection pages and goto the 5th step

d) On the Short Options List, click ‘Exhaustive Options List’ button to list all the Apache/PHP modules.

e) Scroll down a bit and select the “Proxy” module

f) Click ‘Save and Build‘ and proceed to build Apache with the Proxy module.

It may take around 30 minutes for the process to complete. Once the module is compiled, a VirtualHost entry for the cPanel/WHM/Webmail sub-domains is added in the Apache configuration file.

Here’s how to Enable cPanel Proxy for an Existing account:
——————————————————————————————————————————–

2)  The next step is to add ‘A’ records for cPanel/WHM/Webmail for the domain you need to enable proxy access on. To add the records,

a) Goto WHM ->  DNS Functions.

b) Click ‘Edit a DNS Zone’ option and select the domain to edit and click Edit.

c) Scroll down to the empty boxes and add the following records

cpanel 14400 IN A ServerIP
whm 14400 IN A ServerIP
webmail 14400 IN A ServerIP

where, ‘ServerIP’ is the actual IP of the server.

d) Click ‘Save’.

Once the records are added, allow sometime to propagate and then you should be able to access cPanel at, http://cpanel.yourdomain.tld. You will be able to access WHM/Webmail the same way.

Sometimes you see the following error at the middle of your Webmail Horde session :

Your Internet Address has changed since the beginning of your Mail 

session. To protect your security, you must login again.

This error mostly occurs when the ISP is using proxy servers to filter the browsers content. The proxy server randomly change its IP address and thus cause you to fail the web mail security measures.

The solution is to turn off the ‘checkip’ parameter in the Horde’s configuration file.  The configuration file is located as follows:

cPanel server : /usr/local/cpanel/base/horde/config/conf.php
Plesk server  : /usr/share/psa-horde/config/conf.php

Edit the respective configuration file depending on the control panel you have and look for

$conf['auth']['checkip'] = true;

replace it with

$conf['auth']['checkip'] = false;

This is it. Please note, this is a server wide change and cannot be done on user basis.

While accessing an email using Horde, you may notice that Horde isn’t displaying the contents of the email rather it displays the following message

there are no parts that can be displayed inline.

The reason for “no parts can be displayed inline” error is the “inline” setting of the Horde HTML driver is set as false.  To enable the setting, edit the mime_drivers.php file and set the “imp/html/inline” attribute to true.

On a cPanel server, the file is located at /usr/local/cpanel/base/horde/imp/config/mime_drivers.php and the attribute is:

$mime_drivers['imp']['html'] = array(  'inline' => false;

On a Plesk server, the file is located at /etc/psa-horde/imp/mime_drivers.php and the attribute is:

$mime_drivers['imp']['html']['inline'] = false;

Set the value as ‘true’ and save the file. Horde will display the contents properly again.

Recently I had a problem while sending emails to a specific server and while looking at the logs I saw the following:

451-The server has reached its limit for processing requests 

from your host. \n451 Please try again later. 

T=remote_smtp defer (-53): retry time not reached for any host

The reason could either be the, exim rate limiting the number of emails OR the exim databases are corrupted.

In such a case, you have 2 options

1) Increase the number of emails each domain can send per hour from
WHM >> Tweak Settings >> Max hourly emails.

2) If increasing the email limit does not help, surely the exim database is corrupted. The fix is to use the exim database tool called “exim_tidydb“.

SSH to your server and execute:

# /usr/sbin/exim_tidydb -t 1d /var/spool/exim retry > /dev/null 

# /usr/sbin/exim_tidydb -t 1d /var/spool/exim reject > /dev/null 

# /usr/sbin/exim_tidydb -t 1d /var/spool/exim wait-remote_smtp>/dev/null

Once done, reinstall courier and exim using the cPanel scripts.

# /scripts/courierup -- force 

# /scripts/eximup --force

You should now be able to send emails from the server.