Category: Applications

Install and Configure PhpMyAdmin on Centos 7

December 11, 2015 by Dan·0 Comments

PhpMyadmin is a fantastic tool that gives you an easy to use web interface that lets you manage a MySQL database. You can install PhpMyAdmin by downloading the source files from the official website and placing them onto your web server following the config. Better news is that there is actually a package on Centos and Red Had operating systems that will let you install it through the command line.

In order to get access to phpmyadmin via yum you will need to enable the epel repository. Execute the following commands to install epel and phpmyadmin.

yum install epel-release
yum install phpmyadmin

1 2	yum install epel-release yum install phpmyadmin

Once this has completed you will now have phpmyadmin installed on your server. You will need to restart apache in order for it to pick up the new conf files that were created when apache was installed.

service httpd restart

1	service httpd restart

If you now visit “/phpmyadmin” for your website e.g. http://website.com/phpmyadmin. You will be able to gain access to the UI. Chances are you will encounter permission issues trying to access this. I constantly get this error when i first install phpmyadmin. In order to be able to use PhpMyAdmin without getting permission errors go to /etc/httpd/conf.d/phpmyadmin.conf. Replace the contents of the file with the following and restart apache after.

Alias /phpMyAdmin /usr/share/phpMyAdmin
Alias /phpmyadmin /usr/share/phpMyAdmin

<Directory /usr/share/phpMyAdmin/>
AddDefaultCharset UTF-8

<IfModule mod_authz_core.c>
# Apache 2.4
<RequireAny>
#Require ip 127.0.0.1
#Require ip ::1
Require all granted
</RequireAny>
</IfModule>
<IfModule !mod_authz_core.c>
# Apache 2.2
Order Deny,Allow
Deny from All
Allow from 127.0.0.1
Allow from ::1
</IfModule>
</Directory>

Alias /phpMyAdmin /usr/share/phpMyAdmin

Alias /phpmyadmin /usr/share/phpMyAdmin

AddDefaultCharset UTF-8

# Apache 2.4

#Require ip 127.0.0.1

#Require ip ::1

Require all granted

</RequireAny>

</IfModule>

# Apache 2.2

Order Deny,Allow

Deny from All

Allow from 127.0.0.1

Allow from ::1

</IfModule>

</Directory>

Save this file and restart apache

service httpd restart

1	service httpd restart

Try visit the URL again and you should now have access to phpmyadmin.

How To Setup PostfixAdmin With Dovecot and Postfix Virtual Mailbox

December 11, 2015 by Dan·1 Comment

Setting up an email server can be a very daunting task when you aren’t too sure about how an email server works. Thankfully there are tools and configurations you can use that will make the job of managing an email server incredibly easy to understand and perform.

For a long time I was creating new linux OS users to create a new mailbox. The problem here is it meant that only one server could handle a domain, this is when I discovered virtual mailboxes which allows one single server to handle emails for a large number of different domains. A lot of the tutorials out there will show you how to do this using the default database system that postfix uses. This is perfectly fine, but it becomes a major chore to manage when you start to get a large number of domains and emails. After some searching I discovered a web application called postfix admin. This magic piece of software lets you manage all your domains and mailboxes from your web browser without ever needing to ssh into the server. To make things even better, this will also replace the default postfix DB with a much more familiar MySQL database. So lets get to it, this guide will explain everything that you need to know about setting up an email server that uses Postfix and Dovecot with Postfix Admin to manager your sever.

Create Mail User

First thing we want to do is create the mail user. This will be a user that has access to manage all of the files and folders that your mail server will need to manage. The following commands will create a user and configure it with the correct permission and UID. This step is very important as all of the config code below is assuming that you are going to be using the same user created below. If you know what you are doing then of course you can change this to whatever you wish.

groupadd vmail -g 2222
useradd vmail -r -g 2222 -u 2222 -d /var/vmail -m -c "mail user"

1 2	groupadd vmail -g 2222 useradd vmail -r -g 2222 -u 2222 -d /var/vmail -m -c "mail user"

We now have a user and a group called vmail with the uid and gid of 2222. This is the ID that needs to be used when configuring Postfix and Dovecot.

Install And Configure Postfix

First and most important, install your SMTP server. There are various ways in which you can do this depending on your operating system. To install this on a Centos/ Red Hat OS run the following command.

yum install postfix

1	yum install postfix

Once postfix is installed, navigate to /etc/postfix/main.cf. Open this file and edit the contents to make it look like the following.

/etc/postfix/main.cf

queue_directory = /var/spool/postfix
command_directory = /usr/sbin
daemon_directory = /usr/libexec/postfix
data_directory = /var/lib/postfix
mail_owner = postfix
unknown_local_recipient_reject_code = 550
alias_maps = hash:/etc/postfix/aliases
alias_database = $alias_maps

inet_interfaces = all
inet_protocols = ipv4
mydestination = $myhostname, localhost.$mydomain, localhost

debug_peer_level = 2
debugger_command =
         PATH=/bin:/usr/bin:/usr/local/bin:/usr/X11R6/bin
         ddd $daemon_directory/$process_name $process_id & sleep 5

sendmail_path = /usr/sbin/sendmail.postfix
newaliases_path = /usr/bin/newaliases.postfix
mailq_path = /usr/bin/mailq.postfix
setgid_group = postdrop
html_directory = no

relay_domains = *
virtual_mailbox_domains = proxy:mysql:/etc/postfix/sql/mysql_virtual_domains_maps.cf
virtual_alias_maps =
   proxy:mysql:/etc/postfix/sql/mysql_virtual_alias_maps.cf,
   proxy:mysql:/etc/postfix/sql/mysql_virtual_alias_domain_maps.cf,
   proxy:mysql:/etc/postfix/sql/mysql_virtual_alias_domain_catchall_maps.cf
virtual_mailbox_maps =
   proxy:mysql:/etc/postfix/sql/mysql_virtual_mailbox_maps.cf,
   proxy:mysql:/etc/postfix/sql/mysql_virtual_alias_domain_mailbox_maps.cf

virtual_create_maildirsize = yes
virtual_mailbox_extended = yes
virtual_mailbox_limit_maps = mysql:/etc/postfix/sql/mysql_virtual_mailbox_limit_maps.cf
virtual_mailbox_limit_override = yes
virtual_maildir_limit_message = Sorry, the user's maildir has overdrawn his diskspace quota, please try again later.
virtual_overquota_bounce = yes

virtual_mailbox_base = /var/vmail
virtual_minimum_uid = 2222
virtual_transport = virtual
virtual_uid_maps = static:2222
virtual_gid_maps = static:2222

smtpd_sasl_auth_enable = yes
smtpd_sasl_type = dovecot
smtpd_sasl_path = /var/run/dovecot/auth-client
smtpd_sasl_security_options = noanonymous
smtpd_sasl_tls_security_options = $smtpd_sasl_security_options
smtpd_sasl_local_domain = $mydomain
broken_sasl_auth_clients = yes

smtpd_recipient_restrictions = permit_mynetworks, permit_sasl_authenticated, reject_unauth_destination
smtpd_relay_restrictions = permit_mynetworks, permit_sasl_authenticated, reject_unauth_destination

smtpd_milters = inet:127.0.0.1:8891
non_smtpd_milters = $smtpd_milters
milter_default_action = accept
milter_protocol = 2

queue_directory = /var/spool/postfix

command_directory = /usr/sbin

daemon_directory = /usr/libexec/postfix

data_directory = /var/lib/postfix

mail_owner = postfix

unknown_local_recipient_reject_code = 550

alias_maps = hash:/etc/postfix/aliases

alias_database = $alias_maps

inet_interfaces = all

inet_protocols = ipv4

mydestination = $myhostname, localhost.$mydomain, localhost

debug_peer_level = 2

debugger_command =

PATH=/bin:/usr/bin:/usr/local/bin:/usr/X11R6/bin

ddd $daemon_directory/$process_name $process_id & sleep 5

sendmail_path = /usr/sbin/sendmail.postfix

newaliases_path = /usr/bin/newaliases.postfix

mailq_path = /usr/bin/mailq.postfix

setgid_group = postdrop

html_directory = no

relay_domains = *

virtual_mailbox_domains = proxy:mysql:/etc/postfix/sql/mysql_virtual_domains_maps.cf

virtual_alias_maps =

proxy:mysql:/etc/postfix/sql/mysql_virtual_alias_maps.cf,

proxy:mysql:/etc/postfix/sql/mysql_virtual_alias_domain_maps.cf,

proxy:mysql:/etc/postfix/sql/mysql_virtual_alias_domain_catchall_maps.cf

virtual_mailbox_maps =

proxy:mysql:/etc/postfix/sql/mysql_virtual_mailbox_maps.cf,

proxy:mysql:/etc/postfix/sql/mysql_virtual_alias_domain_mailbox_maps.cf

virtual_create_maildirsize = yes

virtual_mailbox_extended = yes

virtual_mailbox_limit_maps = mysql:/etc/postfix/sql/mysql_virtual_mailbox_limit_maps.cf

virtual_mailbox_limit_override = yes

virtual_maildir_limit_message = Sorry, the user's maildir has overdrawn his diskspace quota, please try again later.

virtual_overquota_bounce = yes

virtual_mailbox_base = /var/vmail

virtual_minimum_uid = 2222

virtual_transport = virtual

virtual_uid_maps = static:2222

virtual_gid_maps = static:2222

smtpd_sasl_auth_enable = yes

smtpd_sasl_type = dovecot

smtpd_sasl_path = /var/run/dovecot/auth-client

smtpd_sasl_security_options = noanonymous

smtpd_sasl_tls_security_options = $smtpd_sasl_security_options

smtpd_sasl_local_domain = $mydomain

broken_sasl_auth_clients = yes

smtpd_recipient_restrictions = permit_mynetworks, permit_sasl_authenticated, reject_unauth_destination

smtpd_relay_restrictions = permit_mynetworks, permit_sasl_authenticated, reject_unauth_destination

smtpd_milters = inet:127.0.0.1:8891

non_smtpd_milters = $smtpd_milters

milter_default_action = accept

milter_protocol = 2

One last change to the config files is to the master.cf file. Add or uncomment the following line. There is a good chance the line exists already and its commented (has a # at the start). Removing the hash will do.

/etc/postfix/master.cf

submission inet n       -       n       -       -       smtpd

1	submission inet n - n - - smtpd

you have now setup the cf files, but we still have to setup the database. We are going to use MySQL as this allows us to link it in with a web interface and makes life so much easier. If you look at the contents added to the main.cf file you will see references to a bunch of files in an sql folder. All of these files need to be created. If you have downloaded postfix admin there will be an sh script that you can run and it will generate all of the files for you. This saves you a lot of trouble as these are annoying to write, but to make sure that this guide covers everything I will show you everything that needs to be added for these files. Before we can do this we need to setup PostfixAdmin as this will generate the database that you need to use. So lets setup PostfixAdmin.

Install PostfixAdmin

PostfixAdmin is a free, web interface that allows you to manage the database that postfix uses for virtual users. First things first, download and unzip the latest version of the code, which can be found here http://postfixadmin.sourceforge.net/. You will need to configure apache with an alias or virtualhost depending on what you want to do.

PostfixAdmin comes with its own extensive install guide that comes zipped in the folder. The setup is very straightforward. Run the setup php script through the browser and this will generate the database and add some admin information so you can begin working on it. Once you have it installed and setup, you will now have a database that can be used by postfix. Now we need to tell postfix to actually use this database. We have already instructed postfix that it will be using these files, so all you will need to do is create the following files and add the content to them.

Note: PostfixAdmin comes with a script to generate these files automatically for you. If you run the script (all documented in the setup notes) it will create the files in /tmp. If you decide to do this, take these files and copy them into /etc/postfix/sql and you will be done. If you dont know how to do this you can create them yourself.

Here are the database files that you need to create and add the content to.

/etc/postfix/sql/mysql_virtual_alias_domain_catchall_maps.cf

user = postfix
password = password
hosts = localhost
dbname = postfix
query  = SELECT goto FROM alias,alias_domain WHERE alias_domain.alias_domain = '%d' and alias.address = CONCAT('@', alias_domain.target_domain) AND alias.active = 1 AND alias_domain.active='1'

user = postfix

password = password

hosts = localhost

dbname = postfix

query = SELECT goto FROM alias,alias_domain WHERE alias_domain.alias_domain = '%d' and alias.address = CONCAT('@', alias_domain.target_domain) AND alias.active = 1 AND alias_domain.active='1'

/etc/postfix/sql/mysql_virtual_alias_domain_mailbox_maps.cf

user = postfix
password = password
hosts = localhost
dbname = postfix
query = SELECT maildir FROM mailbox,alias_domain WHERE alias_domain.alias_domain = '%d' and mailbox.username = CONCAT('%u', '@', alias_domain.target_domain) AND mailbox.active = 1 AND alias_domain.active='1'

user = postfix

password = password

hosts = localhost

dbname = postfix

query = SELECT maildir FROM mailbox,alias_domain WHERE alias_domain.alias_domain = '%d' and mailbox.username = CONCAT('%u', '@', alias_domain.target_domain) AND mailbox.active = 1 AND alias_domain.active='1'

/etc/postfix/sql/mysql_virtual_alias_domain_maps.cf

user = postfix
password = password
hosts = localhost
dbname = postfix
query = SELECT goto FROM alias,alias_domain WHERE alias_domain.alias_domain = '%d' and alias.address = CONCAT('%u', '@', alias_domain.target_domain) AND alias.active = 1 AND alias_domain.active='1'

user = postfix

password = password

hosts = localhost

dbname = postfix

query = SELECT goto FROM alias,alias_domain WHERE alias_domain.alias_domain = '%d' and alias.address = CONCAT('%u', '@', alias_domain.target_domain) AND alias.active = 1 AND alias_domain.active='1'

/etc/postfix/sql/mysql_virtual_alias_maps.cf

user = postfix
password = password
hosts = localhost
dbname = postfix
query = SELECT goto FROM alias WHERE address='%s' AND active = '1'
#expansion_limit = 100

user = postfix

password = password

hosts = localhost

dbname = postfix

query = SELECT goto FROM alias WHERE address='%s' AND active = '1'

#expansion_limit = 100

/etc/postfix/sql/mysql_virtual_domains_maps.cf

user = postfix
password = password
hosts = localhost
dbname = postfix
query          = SELECT domain FROM domain WHERE domain='%s' AND active = '1'

user = postfix

password = password

hosts = localhost

dbname = postfix

query = SELECT domain FROM domain WHERE domain='%s' AND active = '1'

/etc/postfix/sql/mysql_virtual_mailbox_limit_maps.cf

user = postfix
password = password
hosts = localhost
dbname = postfix
query = SELECT quota FROM mailbox WHERE username='%s' AND active = '1'

user = postfix

password = password

hosts = localhost

dbname = postfix

query = SELECT quota FROM mailbox WHERE username='%s' AND active = '1'

/etc/postfix/sql/mysql_virtual_mailbox_maps.cf

user = postfix
password = password
hosts = localhost
dbname = postfix
query           = SELECT maildir FROM mailbox WHERE username='%s' AND active = '1'

user = postfix

password = password

hosts = localhost

dbname = postfix

query = SELECT maildir FROM mailbox WHERE username='%s' AND active = '1'

Finally you will need to restart postfix to apply all of the changes that you have made today. Make sure to check the log when restarting to ensure there weren’t any lines that were entered wrong etc.

service postfix restart

1	service postfix restart

Install And Configure Dovecot

Setting up Dovecot is a little less tricky than Postfix and there are less things that can go wrong, so consider the worst out of the way. First things first, let’s install Dovecot.

yum install dovecot

1	yum install dovecot

Once installed, navigate to the install directory and modify the following files.

/etc/dovecot/dovecot.conf

listen = *
ssl = no
protocols = imap lmtp
disable_plaintext_auth = no
auth_mechanisms = plain login
mail_access_groups = vmail
default_login_user = vmail
first_valid_uid = 2222
first_valid_gid = 2222
#mail_location = maildir:~/Maildir
mail_location = maildir:/var/vmail/%d/%n

userdb { 
    driver = sql
    args = /etc/dovecot/dovecot-sql.conf 
}

passdb { 
    driver = sql
    args = /etc/dovecot/dovecot-sql.conf 
}

service auth {
    unix_listener auth-client {
        group = postfix
        mode = 0660
        user = postfix
    }
    user = root
}
service imap-login {
  process_min_avail = 1
  user = vmail
}

listen = *

ssl = no

protocols = imap lmtp

disable_plaintext_auth = no

auth_mechanisms = plain login

mail_access_groups = vmail

default_login_user = vmail

first_valid_uid = 2222

first_valid_gid = 2222

#mail_location = maildir:~/Maildir

mail_location = maildir:/var/vmail/%d/%n

userdb {

driver = sql

args = /etc/dovecot/dovecot-sql.conf

}

passdb {

driver = sql

args = /etc/dovecot/dovecot-sql.conf

}

service auth {

unix_listener auth-client {

group = postfix

mode = 0660

user = postfix

}

user = root

}

service imap-login {

process_min_avail = 1

user = vmail

}

/etc/dovecot/dovecot-sql.conf

connect = host=127.0.0.1 dbname=postfix user=postfix password=password
driver = mysql


# Default password scheme - change to match your Postfixadmin setting.
# depends on your $CONF['encrypt'] setting:
# md5crypt  -> MD5-CRYPT
# md5       -> PLAIN-MD5
# cleartext -> PLAIN
default_pass_scheme = MD5-CRYPT


password_query = SELECT username AS user,password FROM mailbox WHERE username = '%u' AND active='1'

# Query to retrieve user information, note uid matches dovecot.conf AND Postfix virtual_uid_maps parameter.
user_query = SELECT maildir, 2222 AS uid, 2222 AS gid FROM mailbox WHERE username = '%u' AND active='1'


# MYSQL :
user_query = SELECT CONCAT('/var/vmail/', maildir) AS home, 2222 AS uid, 2222 AS gid, CONCAT('*:bytes=', quota) AS quota_rule FROM mailbox WHERE username = '%u' AND active='1'
	
user_query = SELECT maildir, 2222 AS uid, 2222 AS gid, CONCAT('dict:storage=',floor(quota/1000),' proxy::quota') as quota FROM mailbox WHERE username = '%u' AND active='1'

connect = host=127.0.0.1 dbname=postfix user=postfix password=password

driver = mysql

# Default password scheme - change to match your Postfixadmin setting.

# depends on your $CONF['encrypt'] setting:

# md5crypt -> MD5-CRYPT

# md5 -> PLAIN-MD5

# cleartext -> PLAIN

default_pass_scheme = MD5-CRYPT

password_query = SELECT username AS user,password FROM mailbox WHERE username = '%u' AND active='1'

# Query to retrieve user information, note uid matches dovecot.conf AND Postfix virtual_uid_maps parameter.

user_query = SELECT maildir, 2222 AS uid, 2222 AS gid FROM mailbox WHERE username = '%u' AND active='1'

# MYSQL :

user_query = SELECT CONCAT('/var/vmail/', maildir) AS home, 2222 AS uid, 2222 AS gid, CONCAT('*:bytes=', quota) AS quota_rule FROM mailbox WHERE username = '%u' AND active='1'

user_query = SELECT maildir, 2222 AS uid, 2222 AS gid, CONCAT('dict:storage=',floor(quota/1000),' proxy::quota') as quota FROM mailbox WHERE username = '%u' AND active='1'

/etc/dovecot/dovecot-dict-quota.conf

driver = mysql
connect = host=localhost dbname=postfix user=postfix password=password
default_pass_scheme = MD5-CRYPT
table = quota
select_field = current
where_field = path
username_field = username

driver = mysql

connect = host=localhost dbname=postfix user=postfix password=password

default_pass_scheme = MD5-CRYPT

table = quota

select_field = current

where_field = path

username_field = username

This is everything you need to get dovecot working. Note the UID and GID values are using 2222 which is the same value that was setup for the user and group earlier in the tutorial. Of course please change the username/password/db name for all of the SQL queries for everything.

Final Notes

Everything should now be up and running. Restart everything just to make sure that everything is working fresh and clean.

service postfix restart
service dovecot restart

1 2	service postfix restart service dovecot restart

You should be able to navigate to Postfix Admin in your web browser and work away with managing your web server. I understand that this is an incredibly frustrating part of the setup as there are so many things that can go wrong. I have gathered everything that I have encountered from the times when I have set this up. Hopefully everything went well for you, but if not these resources might help you.

Issue Fixes

Hopefully everything went well, but I know all to well that things never go smooth. Chances are you have some issues that you have encountered while setting this up. The following resources might help you solve any issues that you might be getting while setting this up.

Mysql Access Denied

This error is a damn nightmare. It can be one of many things to solve and hopefully its the obvious error that the account you are using has a bad password or does not have the correct permissions to access the database that you are trying to connect to. If you are 100% sure the user has access and can access the database via the command line then it might be an issue with MySQL. The following tutorial may help you get past this issue.

Postfix With Dovecot MySQL Access Denied

Dovecot – unknown database driver MySQL

This is a common issue with a simple fix. It just means that you have not installed the dovecot mysql driver. The following guide will show you how to do this.

Dovecot Error Unknown database driver mysql

Dovecot Error Unknown database driver mysql

December 11, 2015 by Dan·0 Comments

This error might pop up as you are trying to setup your email server. Fear not, there is a good chance that this is not a major issue and can be solved by running one single line of code in the command line.

yum install dovecot-mysql

1	yum install dovecot-mysql

Yep thats it. Dovecot has a mysql driver that it requires in order to be able to communicate with an SQL database. Once you have it installed you should be able to gain access to the database.

service dovecot restart

1	service dovecot restart

Make sure to restart dovecot so the changes take effect.

Postfix With Dovecot MySQL Access Denied

December 11, 2015 by Dan·0 Comments

This error has become the bane of email server management for me. I know the cause and I know how to fix it, yet it always seems to take forever to get it right and it seems to break so very easily. Thankfully after a lot of frustration i have found a very easy way to get past the following error.

dovecot: auth-worker(default): mysql: Connect failed to localhost (mail): Access denied for user ‘postfix’@’localhost’ (using password: YES) - waiting for 1 seconds before retry

1	dovecot: auth-worker(default): mysql: Connect failed to localhost (mail): Access denied for user ‘postfix’@’localhost’ (using password: YES) - waiting for 1 seconds before retry

You have tried granting the user full permissions for everything, you can log in via the command line and nothing appears to be wrong with the user account. I tried all of this too and the problem appears to be the method that MySQL uses to encrypt the passwords. I’m not sure if its dovecot that needs to catch up with this or if SQL is acting up. Either way you can fix this error with the following command.

SET PASSWORD FOR 'postfix'@'localhost' = OLD_PASSWORD('password');

1	SET PASSWORD FOR 'postfix'@'localhost' = OLD_PASSWORD('password');

This will alter the password hash for the user account using the older hashing method. Im not really sure the big details of this, but all i know for sure is that it fixed the issue for me.

Of course this might not be the cause of your error. It might be a simple fact that the login is incorrect or that the user does not have the correct permissions to view the database. However it goes, hopefully this helps and you can get over this issue as easy as possible.

Run Application On Startup With Centos Or RHEL 7

November 24, 2015 by Dan·0 Comments

When running a web server it’s vital that you have you important that you have applications like apache and mysql start when the system does. Who knows what might trigger a reboot and even more, you don’t want to perform a quick restart and have the entire server crumble. Well fear not, it is very easy to set up your system for running applications on system startup.

The following command will work for Centos and Red Hat Linux.

chkconfig --level 234 mysqld on

1	chkconfig --level 234 mysqld on

Run the above command in your command line tool and mysql will be set to start when the system does. Replace mysql with another application name such as httpd to make that application start up on boot too.

How To Lock Users To Home Directory With VSFTP

November 24, 2015 by Dan·0 Comments

It is very easy to lock a user to their home directory. Open up your vsftpd.conf file, which is usually located in “/etc/vsftpd/vsftpd.conf”. Either addor un-comment the following lines from your vsftpd.conf file.

chroot_local_user=YES
chroot_list_enable=YES
# (default follows)
chroot_list_file=/etc/vsftpd/chroot_list

chroot_local_user=YES

chroot_list_enable=YES

# (default follows)

chroot_list_file=/etc/vsftpd/chroot_list

Once you have added the above lines, restart vsftp for the changes to take effect.

service vsftpd restart

1	service vsftpd restart

This will now lock a user to their home directory, preventing them from being able to move outside of their home directory. To correctly use this as an FTP client, you will need to alter the home directory of the linux user to make this work as a full on useful FTP client.

Setup OpenDKIM With Postfix On Linux

November 24, 2015 by Dan·1 Comment

This guide is going to work off the assumption that you already have a functional email server running with postfix on your server. This guide will show you how to setup OpenDKIM with postfix on a linux server

yum install epel-release
yum install opendkim

1 2	yum install epel-release yum install opendkim

Now that opendkim is installed, you need to generate the dkim keys that you need to use to sign the emails with. There are multiple ways to do this. You can do it through the command line or you can use this service http://dkimcore.org/tools/keys.html.

mkdir /etc/opendkim/keys/example.com
chown -R opendkim:opendkim /etc/opendkim/keys/example.com
touch /etc/opendkim/keys/example.com/default

mkdir /etc/opendkim/keys/example.com

chown -R opendkim:opendkim /etc/opendkim/keys/example.com

touch /etc/opendkim/keys/example.com/default

Open up this directory and open the file called “default”. Paste your private key into this file. For safe keeping you could also create another file called “public.txt” and pop the public key into this file so you can access it in the future if you need it.

Sometimes default permissions dont get correctly set. In the event that this happens run the following. There is no harm just running this query anyway.

chown -R opendkim:opendkim /etc/opendkim
chmod -R go-wrx /etc/opendkim/keys

1 2	chown -R opendkim:opendkim /etc/opendkim chmod -R go-wrx /etc/opendkim/keys

Open up “/etc/opendkim.conf” and replace everything with the following

AutoRestart Yes
AutoRestartRate 10/1h
Canonicalization relaxed/simple
ExternalIgnoreList refile:/etc/opendkim/TrustedHosts
InternalHosts refile:/etc/opendkim/TrustedHosts
KeyTable refile:/etc/opendkim/KeyTable
LogWhy Yes
Mode sv
PidFile /var/run/opendkim/opendkim.pid
SignatureAlgorithm rsa-sha256
SigningTable refile:/etc/opendkim/SigningTable
Socket inet:8891@localhost
Syslog Yes
SyslogSuccess Yes
TemporaryDirectory /var/tmp
UMask 022
UserID opendkim:opendkim

AutoRestart Yes

AutoRestartRate 10/1h

Canonicalization relaxed/simple

ExternalIgnoreList refile:/etc/opendkim/TrustedHosts

InternalHosts refile:/etc/opendkim/TrustedHosts

KeyTable refile:/etc/opendkim/KeyTable

LogWhy Yes

Mode sv

PidFile /var/run/opendkim/opendkim.pid

SignatureAlgorithm rsa-sha256

SigningTable refile:/etc/opendkim/SigningTable

Socket inet:8891@localhost

Syslog Yes

SyslogSuccess Yes

TemporaryDirectory /var/tmp

UMask 022

UserID opendkim:opendkim

You now need to add a key to the keytable. This file is located in /etc/opendkim/keytable

default._domainkey.example.com example.com:default:/etc/opendkim/keys/example.com/default

1	default._domainkey.example.com example.com:default:/etc/opendkim/keys/example.com/default

You will also need to add a line to the signing table.
If the file doesnt exist, create it. “/etc/opendkim/SigningTable”

*@example.com default._domainkey.example.com

1	*@example.com default._domainkey.example.com

Open or create “/etc/opendkim/TrustedHosts” and add the following.

127.0.0.1
hostname1.example1.com
example1.com
hostname1.example2.com
example2.com

127.0.0.1

hostname1.example1.com

example1.com

hostname1.example2.com

example2.com

Add the following to your postfix main.cf file. This will instruct postfix to sign the emails with the DKIM key you setup.

smtpd_milters = inet:127.0.0.1:8891
non_smtpd_milters = $smtpd_milters
milter_default_action = accept
milter_protocol = 2

smtpd_milters = inet:127.0.0.1:8891

non_smtpd_milters = $smtpd_milters

milter_default_action = accept

milter_protocol = 2

Thats all thats needed. Now run opendkim and restart postfix and you should be good to go.

service opendkim start
service postfix restart

1 2	service opendkim start service postfix restart

Setting Up A WordPress Content Filter

August 23, 2015 by Dan·0 Comments

Content filters are used to display some data at a specific location in a post. For example, if you wanted to display some data at the end of every single post on your blog, you could use a content filter and it would allow you to do this. You will need to be able to write PHP code in order to do this. If you follow my full WordPress Plugin Tutorial you should be able to build an entire plugin from start to finish without too much trouble.

So to start off, you will need to have your own custom plugin created. If you do not know how to do this, follow my guide on creating a WordPress plugin template. A plugin is very simple to create, so don’t worry if you aren’t particularly strong at programming in PHP.

Step 1 – Register The Content Filter In The Main Plugin File

Open up your plugin and go to the main php file (usually the same name as the plugin itself) and you can add the filter that will use “the_content” as the data that will be filtered. This means that when wordpress is loading the page and it comes to the point where it loads the content of the post, it will check to see if there are any filters that have been added. If it finds a filter for “the_content” it will run the function that is defined in the filter.

The following code will add a filter that is triggered when WordPress is loading the post content and it will then call a function called myinfo_filter().

add_filter( "the_content", "myinfo_filter");

1	add_filter( "the_content", "myinfo_filter");

Step 2 – Create The Filters Function

In order to make this code work we are going to need to create a function called myinfo_filter. The function is just a standard PHP function that will have 2 simple requirements. It must accept a variable that contains the content of the entire post and it must also return the content for the post.

When WordPress reads the code above it will call a function called myinfo_filter and it will give this function all of the content from the post. If you do not return any data the post will show up blank. If you do not add the function you will get a fatal exception. So lets add a simple function that will append some data onto the end of the post.

This function will accept the content from the post and if this is a single page ie. a post. it will add ” CUSTOM CONTENT!” onto the end of the post. This will show up for every single post on your blog. You can add some more advanced logic here to append something more substantial to the end of the post.

function myinfo_filter($content)
{
	if(is_single())
	{	
		return $content . " CUSTOM CONTENT!";
	}
	else
	{
		return $content;
	}
}

function myinfo_filter($content)

{

if(is_single())

{

return $content . " CUSTOM CONTENT!";

}

else

{

return $content;

}

You could also append the data to the start of the post by doing the exact same thing except putting the data at the start.

return "Custom Content ".$content;

1	return "Custom Content ".$content;

Save the file and your filter should now be adding content to the end of your post.

How To Clear WordPress Sidebar Cache For Sidebar Login

August 15, 2015 by Dan·2 Comments

I recently encountered an issue where users were logging in using a sidebar login form, but when they got redirected back to the page they logged in from, the login box was still present. When you visit another page on the site, the login box was gone and the user was showing up as being logged in, yet the origin page where the login was performed was not showing this login box, even with ctrl+f5.

I looked into this further and the session variables were being set and the login was definitely working correctly. The problem is definitely a cache issue, but I couldn’t find out what is causing it. I didn’t have any cache plugin installed and I double checked my .htaccess to make sure Apache wasn’t caching anything. Fortunately I was able to come up with a quick and easy solution to bypass this issue.

WordPress itself seems to be caching pages based on the URL. The sidebar in particular is something that gets cached. Clearing the cache every time someone logs in, doesn’t seem like a good idea to me so I came up with an alternative that works just as well.

When a user clicks the login button it will send a POST to another php script. This script will then check the login and redirect back to the origin page. Rather than use this.

header ("Location: {$redirectUrl}");

1	header ("Location: {$redirectUrl}");

I appended a random variable onto the end of the URL. This causes wordpress to ignore the cache

header ("Location: {$redirectUrl}?login=true");

1	header ("Location: {$redirectUrl}?login=true");

When the login form redirects back to this URL the user account box was displaying and the cache issue was resolved. This might not be the official solution to the problem, but it’s a quick and easy solution that worked well for me.

Creating A WordPress Plugin Template

August 15, 2015 by Dan·1 Comment

Creating a wordpress plugin is a lot easier than it might first seem. As long as you know how to write PHP code (or any similar language) you should be able to get a plugin together pretty quickly. The aim of this tutorial is to show you how to create a basic template for a plugin that will show up in the WordPress plugin menu.

Start by navigating to the plugins directory for your WordPress install. This directory is located at “wp-content/plugins/”. In this directory create a new folder named after the plugin that you want to create. E.g. “plugin-test”. Inside this directory create a php file with the same name, so “plugin-test.php”. Open up this php file and add the following code.

<?php 
/*
Plugin Name: My Test Plugin
Description: This is a test plugin 
Version:     1.0
Author:      Dan Hastings
Author URI:  http://yomotherboard.com
*/
?>

<?php

Plugin Name: My Test Plugin

Description: This is a test plugin

Version: 1.0

Author: Dan Hastings

Author URI: http://yomotherboard.com

Save this file and that is it. You now have a plugin template created. You don’t need to do any additional work to register this plugin with your WordPress install. If you open your web browser and log into your WordPress install. Go to the plugins tab and you will see that the test plugin that you just created now shows up on this list. You can activate the plugin, but it will not do anything as you have not added any code to the plugin.

Now that you have an active plugin registered within your WordPress install, you can start adding any custom features that you want.