Integration/OpenVPN.iRedMail.with.OpenLDAP/CentOS

From iRedMail

Install OpenVPN

Use EPEL yum repository to install OpenVPN.

rpm -Uhv http://download.fedora.redhat.com/pub/epel/5/i386/epel-release-5-3.noarch.rpm # <-- For i386
rpm -Uhv http://download.fedora.redhat.com/pub/epel/5/x86_64/epel-release-5-3.noarch.rpm # <-- For x86_64 

Install OpenVPN and ldap support

yum install openvpn openvpn-auth-ldap
chkconfig openvpn on 

Install dnsmasq (Optional):Forward DNS traffic through the VPN you will need to install the dnsmasq package

yum install dnsmasq
/etc/init.d/dnsmasq start
chkconfig dnsmasq on 

easy-rsa

The OpenVPN package provides a set of encryption-related tools called "easy-rsa". These scripts are located by default in the /usr/share/doc/openvpn/examples/easy-rsa/ directory. However, in order to function properly, these scripts should be located in the /etc/openvpn directory. We also need copy the Openvpn config example file to /etc/openvpn

cp -R /usr/share/openvpn/easy-rsa/ /etc/openvpn

Configure Public Key Infrastructure Variables

Before we can generate the public key infrastructure for OpenVPN we must configure a few variables that the easy-rsa scripts will use to generate the scripts. These variables are set near the end of the /etc/openvpn/easy-rsa/2.0/vars file. Here is an example of the relevant values:

• Open /etc/openvpn/easy-rsa/2.0/vars and set correct values:

export KEY_COUNTRY="CN"
export KEY_PROVINCE="BJ"
export KEY_CITY="BeiJing"
export KEY_ORG="iredmail"
export KEY_EMAIL="www@example.com"

Initialize the Public Key Infrastructure (PKI)

Issue the following three commands in sequence to internalize the certificate authority and the public key infrastructure:

cd /etc/openvpn/easy-rsa/2.0/
chmod +rwx *
source ./vars
./clean-all
./pkitool --initca

Generate Certificates

With the certificate authority generated you can generate the private key for the server. This script will also prompt you for additional information. By default, the Common Name for this key will be "server". You can change these values in cases where it makes sense to use alternate values. To accomplish this, issue the following command:

./pkitool --server server 

Generate Diffie Hellman Parameters Link

The "Diffie Hellman Parameters" govern the method of key exchange and authentication used by the OpenVPN server. Issue the following command to generate these parameters:

./build-dh 

Relocate Secure Keys

The keys and certificates for the server need to be relocated to the /etc/openvpn directory so the OpenVPN server process can access them. These files are:

• ca.crt
• ca.key
• dh1024.pem
• server.crt
• server.key

cp keys/{ca.crt,ca.key,server.crt,server.key,dh1024.pem} /etc/openvpn/ 

These files no need leave your server. Maintaining integrity and control over these files is of the utmost importance to the integrity of your server. If you ever need to move or back up these keys, ensure that they're encrypted and secured.

Config OpenVPN support OpenLDAP auth

Find cn=vmail password

vmail password was random create duiring iredmail install.you can find the password in /etc/postfix/ldap_virtual_mailbox_domains.cf

• Open /etc/postfix/ldap_virtual_mailbox_domains.cf and check values:

bind_dn         = cn=vmail,dc=example,dc=com
bind_pw         = InYTi8qGjamTb6Me2ESwbb6rxQUs5y #cn=vmail password

Configure LDAP auth

• Open /etc/openvpn/auth/ldap.conf and set correct values:

<LDAP>
# LDAP server URL
URL             ldap://localhost
# Bind DN (If your LDAP server doesn't support anonymous binds)
BindDN                cn=vmail,dc=example,dc=com
# Bind Password cn=vmail password
Password      InYTi8qGjamTb6Me2ESwbb6rxQUs5y
# Network timeout (in seconds)
Timeout         15
</LDAP>


<Authorization>
# Base DN
BaseDN          "o=domains,dc=example,dc=com"
# User Search Filter
SearchFilter    "(&(objectClass=mailUser)(accountStatus=active)(enabledService=vpn))"
# Require Group Membership
RequireGroup    false
</Authorization>

Configuring OpenVPN

We'll now need to configure our server file. There is an example file in /usr/share/doc/openvpn-2.1.1/examples/sample-config-files. Issue the following sequence of commands to retrieve the example configuration files and move them to the required directories:

cp /usr/share/doc/openvpn-2.1.1/sample-config-files/server.conf /etc/openvpn/ 

• Open /etc/openvpn/server.conf and set correct values:

push "redirect-gateway def1"
push "dhcp-option DNS 10.8.0.1"
plugin /usr/lib/openvpn/plugin/lib/openvpn-auth-ldap.so /etc/openvpn/auth/ldap.conf
client-cert-not-required

Enable VPN service for mail user

Use phpLDAPadmin or other tools to add LDAP values for exist mail user.

• Login in the phpLDAPadmin
• Find the exit mail user www@example.com
• Enable VPN service for the user www@example.com.

Enable IP forward and config iptables

• Open /etc/sysctl.conf and set correct values:

net.ipv4.ip_forward = 1

Issue the following commands to configure iptables to properly forward traffic through the VPN:

echo 1 > /proc/sys/net/ipv4/ip_forward 

• Open /etc/sysconfig/iptables and add the below. Let the iptables open 1194 ports.:

#openvpn
-A INPUT -p udp -m multiport --dport 1194 -j ACCEPT

Issue the following command to set this variable for the current session:

iptables -A FORWARD -m state --state RELATED,ESTABLISHED -j ACCEPT
iptables -A FORWARD -s 10.8.0.0/24 -j ACCEPT
iptables -A FORWARD -j REJECT
iptables -t nat -A POSTROUTING -s 10.8.0.0/24 -o eth0 -j MASQUERADE

Before continuing, insert these iptables rules into your system's /etc/rc.local file to ensure that theses iptables rules will be recreated following your next reboot cycle:

• Open /etc/rc.local and let look like:

#!/bin/sh
#
# [...]
#

iptables -A FORWARD -m state --state RELATED,ESTABLISHED -j ACCEPT
iptables -A FORWARD -s 10.8.0.0/24 -j ACCEPT
iptables -A FORWARD -j REJECT
iptables -t nat -A POSTROUTING -s 10.8.0.0/24 -o eth0 -j MASQUERADE

touch /var/lock/subsys/local

Restart relate service

we need restart all relate service, let the cofig work.

/etc/init.d/ldap restart
/etc/init.d/openvpn restart
/etc/init.d/iptables restart 

Client setting

cp /usr/share/doc/openvpn-2.1.1/sample-config-files/client.conf /etc/openvpn/easy-rsa/2.0/keys/client.ovpn
cd /etc/openvpn/easy-rsa/2.0/keys 

• Open /etc/openvpn/easy-rsa/2.0/keys/client.ovpn and set correct values:

# Add the vpn server
remote mail.example.com 1194

[...]
#Comment out the below two line  
#cert client.crt
#key client.key

[...]
#Add thes line at the botton
auth-user-pass

Copy the client.ovpn and ca.crt file to your client system. Also can use mutt sent the files to mailbox. you can login email account and download the fies.

yum -y install mutt zip
cd /etc/openvpn/easy-rsa/2.0/keys
zip config.zip client.ovpn ca.crt
mutt -s "OpenVPN client config files" -a /etc/openvpn/easy-rsa/2.0/keys/config.zip www@example.com < /usr/share/doc/openvpn-2.1.1/README 

Installing OpenVPN GUI On Windows XP / Vista

Download the client software here:http://www.openvpn.se/development.html . The tested version is OpenVPN 2.1_beta7 & OpenVPN GUI 1.0.3 , works on Vista. After install, put the client.ovpn and ca.crt file to C:\Program Files\OpenVPN\config.

Now you can use the account www@example.com connect the vpn.