1. install prerequisite package for zimbra
   yum install sudo sysstat libidn gmp litool-ltdl compat-glib vixie-cron nc perl libstdc++.i686
   yum -y install nc wget nano make nc sudo sysstat libtool-ltdl glibc perl ntp
2. modify /etc/hosts file
   nano /etc/hosts
   ip address mail.nextzone.com mail

1. modify /etc/sudoers file
   nano /etc/sudoers
   comment out # Defaults requiretty *line

1. check zimbra status
   su – zimbra
   zmcontrol status

13.Go to admin colsole
click on configure opton
then click on Global Settings
then click on MTA option
uncheck TLS authentication only
uncheck Enable DNS lookups option

Installing Squid

1. Squid is available in the CentOS repositories. To ensure your system is up-to-date and install Squid run the following commands:

   sudo yum update
   sudo yum install squid

2. Copy the original configuration file to keep as a backup:

   sudo cp /etc/squid/squid.conf /etc/squid/squid.conf.default

Configuring Squid as an HTTP proxy

Basic Setup

1. Edit the Squid configuration file and add the following lines:

   /etc/squid/squid.conf

   acl client src 12.34.56.78 # Home IP http\_access allow client

1. Once you’ve saved and exited the file, start Squid:

   sudo service squid restart

2. At this point you can configure your local browser or operating system’s network settings to use your Linode as an HTTP proxy. How to do this will depend on your choice of OS and browser. Once you’ve made the change to your settings, test the connection by pointing your browser at a website that tells you your IP address, such as ifconfig, What is my IP, or by Googling What is my ip.
3. Additional clients can be defined by adding new acl lines to /etc/squid/squid.conf. Access to the proxy is granted by adding the name defined by each acl to the http_access allow line.

Advanced Authentication

1. You will need the htpasswd utility. If you’ve installed Apache on your Linode, you will already have it. Otherwise run:

   sudo yum install httpd-tools

2. Create a file to store Squid users and passwords, and change ownership:

   sudo touch /etc/squid/squid_passwd
   sudo chown squid /etc/squid/squid_passwd

3. Create a username password pair:

   sudo htpasswd /etc/squid/squid_passwd user1

   Replace user1 with a username. You will be prompted to create a password for this user:

   New password:
   Re-type new password:
   Adding password for user user1

   You can repeat this step at any time to create new users.
4. Edit the Squid configuration file and add the following lines:

   File/etc/squid/squid.conf

   auth_param basic program /usr/lib64/squid/ncsa_auth /etc/squid/squid_passwd
   acl ncsa_users proxy_auth REQUIRED
   http_access allow ncsa_users

5. Once you’ve saved and exited the file, restart Squid:

   sudo service squid restart

6. At this point, you can configure your local browser or operating system’s network settings to use your Linode as an HTTP proxy. You will need to specify that the server requires authentication, and provide the username and password. How to do this will depend on your choice of OS and browser. Once you’ve made the settings change, test the connection by pointing your browser at a website that tells you your IP address, such as ifconfig, What is my IP, or by Googling What is my ip.
7. To remove a user’s access to the proxy, you must delete their entry in the squid_passwd file. Each user is represented in the file on a single line in the format of user:passwordhash :

   /etc/squid/squid_passwd

   user1:gh48gfno user2:9b83v5hd

   If you are using Nano, the command Control+k will remove the entire line where the cursor rests. Once you’ve saved and exited the file, restart Squid:

   sudo service squid restart

Anonymizing Traffic

file /etc/squid/squid.conf

forwarded_for off
request_header_access Allow allow all
request_header_access Authorization allow all
request_header_access WWW-Authenticate allow all
request_header_access Proxy-Authorization allow all
request_header_access Proxy-Authenticate allow all
request_header_access Cache-Control allow all
request_header_access Content-Encoding allow all
request_header_access Content-Length allow all
request_header_access Content-Type allow all
request_header_access Date allow all
request_header_access Expires allow all
request_header_access Host allow all
request_header_access If-Modified-Since allow all
request_header_access Last-Modified allow all
request_header_access Location allow all
request_header_access Pragma allow all
request_header_access Accept allow all
request_header_access Accept-Charset allow all
request_header_access Accept-Encoding allow all
request_header_access Accept-Language allow all
request_header_access Content-Language allow all
request_header_access Mime-Version allow all
request_header_access Retry-After allow all
request_header_access Title allow all
request_header_access Connection allow all
request_header_access Proxy-Connection allow all
request_header_access User-Agent allow all
request_header_access Cookie allow all
request_header_access All deny all

sudo service squid restart

Squid Official Site

$ hostname -f
mx.example.com

• For RHEL/CentOS/Scientific Linux 6, hostname is defined in /etc/sysconfig/network:

HOSTNAME=mx.example.com

mx.example.com

• /etc/hosts: hostname <=> IP address mapping. Warning: List the FQDN hostname as first item.

127.0.0.1   mx.example.com mx localhost localhost.localdomain

$ hostname -f
mx.example.com

Disable SELinux.

SELINUX=disabled

SELINUX=permissive

# setenforce 0

Enable yum repositories for installing new packages

• For CentOS or Scientific Linux, please enable CentOS/Scientific official yum repositories, and DISABLE all third-party yum repositories to avoid package conflict.
• For Red Hat Enterprise Linux, please enable Red Hat Network to install packages, or create a local yum repository with DVD/CD ISO images.

• Download the latest release of iRedMail

• Visit Download page to get the latest stable release of iRedMail.
• Uncompress iRedMail tarball:

# cd /root/
# tar xjf iRedMail-x.y.z.tar.bz2

Start iRedMail installer

It's now ready to start iRedMail installer, it will ask you several simple questions, that's all required to setup a full-featured mail server.

# cd /root/iRedMail-x.y.z/
# bash iRedMail.sh

Note to Chinese Users
Our domain name iredmail.org has been blocked in mainland China for years (since Jun 04, 2011), please run command below to finish the installation:
IREDMAIL_MIRROR='http://42.159.241.31' bash iRedMail.sh
Additional variables are:
• EPEL repo: IREDMAIL_EPEL_MIRROR='http://mirrors.aliyun.com/epel'
• SOGo repo: SOGO_PKG_MIRROR='http://42.159.241.31/SOGo'

Screenshots of installation:

• Welcome and thanks for your use

• Specify location to store all mailboxes. Default is /var/vmail/.

• Choose backend used to store mail accounts. You can manage mail accounts with iRedAdmin, our web-based iRedMail admin panel.

Note

There's no big difference between available backends, so it's strongly recommended to choose the one you're familiar with for easier management and maintenance after installation.

• If you choose to store mail accounts in OpenLDAP, iRedMail installer will ask to set the LDAP suffix.

• Add your first mail domain name

• Set password of admin account of your first mail domain.

Note: This account is an admin account and a mail user. That means you can login to webmail and admin panel (iRedAdmin) with this account, login username is full email address.

• Choose optional components

After answered above questions, iRedMail installer will ask you to review and confirm to start installation. It will install and configure required packages automatically. Type y or Y and press Enter to start.