installing openvpn on centos

8/18/2019 Installing OpenVPN on CentOS

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Installing OpenVPN on CentOS 5 andCentOS 6

03 Apr 2012/200 Comments/in VPN's /b Admin

In this guide we will show you how to setup OpenVPN on centos – the guide will give you a

fully working OpenVPN installation,NOT TESTED ON OTHER DISTROS..

First step is to check if tun/tap is active:

cat /dev/net/tun

If tun is active then you should see this:

cat: /dev/net/tun: File descriptor in bad state

Make sure you have these packages installed:

yum install gcc make rpm-build autoconf.noarch zlib-devel pam-devel openssl-devel -y

Download LZO RPM and Configure RPMForge Repo:

http://safesrv.net/install-openvpn-on-centos/http://safesrv.net/install-openvpn-on-centos/http://safesrv.net/install-openvpn-on-centos/#commentshttp://safesrv.net/category/vpns/http://safesrv.net/author/ssadmin/http://safesrv.net/install-openvpn-on-centos/#commentshttp://safesrv.net/category/vpns/http://safesrv.net/author/ssadmin/http://safesrv.net/install-openvpn-on-centos/http://safesrv.net/install-openvpn-on-centos/


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wget http://openvpn.net/release/lzo-1.0-!.rf.src.rpm

32bit Package:

CentOS 5:

wget http://packages.sw.be/rpmforge-release/rpmforge-release-0.".#-#.el".rf.i$%.rpm

CentOS 6:

&get http://pkgs.repoforge.org/rpmforge-release/rpmforge-release-0.".$-

1.el%.rf.i%%.rpm

64bit Package:

CentOS 5:

wget http://packages.sw.be/rpmforge-release/rpmforge-release-0.".#-#.el".rf.'%(%!.rpm

CentOS 6:


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wget http://pkgs.repoforge.org/rpmforge-release/rpmforge-release-0.".$-

1.el%.rf.'%(%!.rpm

Build the rpm packages:

rpmbuild --rebuild lzo-1.0-!.rf.src.rpm

rpm -)vh lzo-*.rpm

rpm -)vh rpmforge-release*

Install OpenVPN:

yum install openvpn -y

Copy the easy-rsa folder to /etc/openvpn/:

cp -+ /usr/share/doc/openvpn-#.#.#/easy-rsa/ /etc/openvpn/


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**PLEASE NOTE** if the above command brings up an error such as below, then please

follow the following steps to download and copy over easy-rsa as its not included in the new

build OpenVPN 2.3.1:

cannot stat `/usr/share/doc/openvpn-2.2.2/easy-rsa/': No such fle or

directory

Download easy-rsa from below:

wget https://github.com/downloads/,pen/easy-rsa/easy-rsa-#.#.0(master.tar.gz

Extract the package:

tar -z'vf easy-rsa-#.#.0(master.tar.gz

Copy to OpenVPN directory:

cp -+ easy-rsa-#.#.0(master/easy-rsa/ /etc/openvpn/

Please note onCentOS 6 we need to make a small change before you run the commands

below, open up/etc/!en"!n/ea#$%a/2.'/"a and edit the below line:

Change:


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e'port 2(3,F4567892(+9/whichopensslcnf 892(+97

To:

e'port 2(3,F456/etc/openvpn/easy-rsa/#.0/openssl-1.0.0.cnf

And save..

Now let’s create the certificate:

cd /etc/openvpn/easy-rsa/#.0

chmod ;"" *

source ./vars

./vars

./clean-all

Build CA:


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./build-ca

C(nt&$ Na)e: may be filled or press enter

State & P&"ince Na)e: may be filled or press enter

Cit$: may be filled or press enter

O&g Na)e: may be filled or press enter

O&g nit Na)e: may be filled or press enter

C))n Na)e: your server hostname

E)ai+ A,,&e##: may be filled or press enter

Build key server:

./build-key-server server

9lmost the same with ./build.ca but check the changes and additional

C))n Na)e: server

A c-a++enge !a##&,: leave

O!tina+ c)!an$ na)e: fill or enter

#ign t-e ce&ticate: y

0 (t 1 0 ce&ticate &e(e#t#: y

Build Diffie Hellman (wait a moment until the process finish):


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./build-dh

Now create your config file:

touch /etc/openvpn/server.conf

And enter the following:

port 11

proto udp =- protocol

dev tun

tun-mtu 1"00

tun-mtu-e'tra $#

mssfi' 1!"0

reneg-sec 0


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ca /etc/openvpn/easy-rsa/#.0/keys/ca.crt

cert /etc/openvpn/easy-rsa/#.0/keys/server.crt

key /etc/openvpn/easy-rsa/#.0/keys/server.key

dh /etc/openvpn/easy-rsa/#.0/keys/dh10#!.pem

plugin /usr/share/openvpn/plugin/lib/openvpn-auth-pam.so /etc/pam.d/login =- 3omment

this line if you are using Free+9>4)

=plugin /etc/openvpn/radiusplugin.so /etc/openvpn/radiusplugin.cnf =- )ncomment this

line if you are using Free+9>4)

client-cert-not-re?uired

username-as-common-name

server 10..0.0 #"".#"".#"".0

push @redirect-gateway def1@

push @dhcp-option > ...@

push @dhcp-option > ..!.!@


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keepalive " $0

comp-lzo

persist-key

persist-tun

status 11

verb $

Save it.

Before we start OpenVPN, lets disable SELinux if enabled, this can cause issues with

OpenVPN, especially when using OpenVPN with multiple configs:

echo 0 A /selinu'/enforce

This is a temporary solution and will re-enable once you reboot your system, to disable on a

permanent basis you need to edit the following/etc/#e+in(/cng and edit this line:

B4)C6enforcing


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To:

B4)C6disabled

When your system next reboots it will still be disabled.

Now lets start OpenVPN:

service openvpn restart

*Please note if you receive “FAIL” when OpenVPN trys to start and you have the following

error in your/"a&/+g/)e##age#:

B)54(44D: could not load plugin shared obEect

/usr/share/openvpn/plugin/lib/openvpn-auth-pam.so:

/usr/share/openvpn/plugin/lib/openvpn-auth-pam.so: cannot open shared obEect file: o

such file or directory

Then this is because the latest OpenVPN package doesn’t include this file (which is

reported to be fixed soon) but you can download the pam auth file from here for now:

64Bit:


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wget http://safesrv.net/public/openvpn-auth-pam.zip

32Bit:

wget http://safesrv.net/public/dl/openvpn-auth-pam.zip

Extract the file:

unzip openvpn-auth-pam.zip

Move to the OpenVPN directory:

mv openvpn-auth-pam.so /etc/openvpn/openvpn-auth-pam.so

Then replace the PAM plugin line in your server.conf to below:

plugin /etc/openvpn/openvpn-auth-pam.so /etc/pam.d/login

Restart OpenVPN and all should now work:


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killall -< openvpn

service openvpn restart

Now we need to enable IP forwarding. So open the file/etc/#$#ct+.cn1 and set

‘net.ipv4.ip_forward’ to 1.

net.ipv!.ip(forward 6 1

To make the changes to sysctl.conf take effect, use the following command.

sysctl -p

Route Iptables:

T-e &(+e be+ i++ &k ne n en an, 5 ba#e, 5PS7# b(t 1&

O!en58 (#e t-e O!en58 i!tab+e &(+e in#tea,:

iptables -t nat -9 ,D+,)D45 -s 10..0.0/#! -o eth0 -E 9G)+9>

O!en58 i!tab+e &(+e#:


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iptables -t nat -9 ,D+,)D45 -o venet0 -E 9D --to-source 1#$.1#$.1#$.1#$

And

iptables -t nat -9 ,D+,)D45 -s 10..0.0/#! -E 9D --to-source 1#$.1#$.1#$.1#$

Make sure you change 123.123.123.123 to your server IP.

IF you have CSF on the same server you need to open your OpenVPN port (Usually 1194)

through the firewall and run the below commands for CSF, also its a good idea to add them

to/etc/c#1/c#1!&e.#-.

iptables -9 F,+&9+> -m state --state +B9D>HD9IB4J> -E 933D

iptables -9 F,+&9+> -s 10..0.0/#! -E 933D

iptables -9 F,+&9+> -E +K3D


iptables -t nat -9 ,D+,)D45 -E 9D --to-source 1#$.1#$.1#$.1#$

If the above rules cause you any problems or don’t seem to work (Especially on cPanel

servers) then remove the rules above and use below:


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iptables -9 F,+&9+> -i tun0 -o eth0 -E 933D

iptables -9 F,+&9+> -i eth0 -o tun0 -E 933D

Please make sure 123.123.123.123 is your main server IP.

Then run…

service iptables save

Please note if you are using our FreeRADIUS module for WHMCS then you don’t have to do

the below step for adding users just follow the link above to setup OpenVPN to auth offFreeRADIUS – otherwise you can create a user as follows:

useradd username -s /bin/false

passwd username

If you wanted to delete a user you would use:


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userdel username

Now create a server.ovpn config file and enter the following:

client

dev tun

proto udp

remote 1#$.1#$.1#$.1#$ 11

resolv-retry infinite

nobind

tun-mtu 1"00

tun-mtu-e'tra $#

mssfi' 1!"0

persist-key


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persist-tun

ca ca.crt

auth-user-pass

comp-lzo

reneg-sec 0

verb $

Make sure you change 123.123.123.123 to your server IP.

And make sure OpenVPN starts at boot:

chkconfig openvpn on

Download ca.crt file in/etc/!en"!n/ea#$%a/2.'/ke$#/ directory and place it in the

same directory as your server.ovpn.

Now download a VPN client and import your config file and enter your username and

password created above

installing openvpn on centos

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