help installing openvpn

[shinjikenny]

i'm new to linux and I want to learn how to install openvpn on an openvz vps.
i'm following this instruction:

I have searched this forum and i don't find any OPENVPN tutorial, so i'll write tutorial how to make OPENVPN running on CentOS, hope it will be useful.

Here i'm using OpenVZ VPS with CentOS 5.5 32bit, and about the memory requirement? Don't worry, OPENVPN doesn't eat your memory too much, i have 50 user running in my 128MB vps and it only eats 25MB memory

First thing you have to do is check whether tun/tap is active or not by typing
#cat /dev/net/tun

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

take a look at the status above, "File descriptor in bad state" means tun/tap is active, otherwise please ask your provider to activate it

Install required modules
#yum install gcc make rpm-build autoconf.noarch zlib-devel pam-devel openssl-devel

Download OPENVPN repo
#wget http://openvpn.net/release/lzo-1.08-4.rf.src.rpm

for 32bit
#wget http://packages.sw.be/rpmforge-release/rpmforge-release-0.5.2-2.el5.rf.i386.rpm

for 64bit
#wget http://packages.sw.be/rpmforge-release/rpmforge-release-0.5.2-2.el5.rf.x86_64.rpm

Build the rpm packages
#rpmbuild --rebuild lzo-1.08-4.rf.src.rpm
#rpm -Uvh /usr/src/redhat/RPMS/i386/lzo-*.rpm
#rpm -Uvh rpmforge-release-0.5.2-2.el5.rf.i386.rpm

*remember to change i386 to x86_64 if you're using 64bit

Install OPENVPN
#yum install openvpn

Copy OPENVPN easy-rsa folder to /etc/openvpn/
#cp -R /usr/share/doc/openvpn-2.1.4/easy-rsa/ /etc/openvpn/

Now let's create the certificate
#cd /etc/openvpn/easy-rsa/2.0
#chmod 755 *
#source ./vars
#./vars
#./clean-all

Build CA
#./build-ca

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[B]Country Name:[/B] may be filled or press enter
[B]State or Province Name:[/B] may be filled or press enter
[B]City:[/B] may be filled or press enter
[B]Org Name:[/B] may be filled or press enter
[B]Org Unit Name:[/B] may be filled or press enter
[B]Common Name:[/B] your server hostname
[B]Email Address:[/B] may be filled or press enter

Build key server
#./build-key-server server

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Almost the same with ./build.ca but check the changes and additional
[B]Common Name:[/B] [COLOR="Red"]server[/COLOR]
[B]A challenge password:[/B] leave
[B]Optional company name:[/B] fill or enter
[B]sign the certificate:[/B] y
[B]1 out of 1 certificate requests:[/B] y

Build Diffie Hellman (wait a moment until the process finish)
#./build-dh

Now i'm gonna create UDP port 1194 configuration for OPENVPN, use any text editor you like
#nano /etc/openvpn/1194.conf

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local 123.123.123.123 #- your_server_ip
port 1194 #- port
proto udp #- protocol
dev tun
tun-mtu 1500
tun-mtu-extra 32
mssfix 1450
ca /etc/openvpn/easy-rsa/2.0/keys/ca.crt
cert /etc/openvpn/easy-rsa/2.0/keys/server.crt
key /etc/openvpn/easy-rsa/2.0/keys/server.key
dh /etc/openvpn/easy-rsa/2.0/keys/dh1024.pem
[COLOR="Red"]plugin /usr/share/openvpn/plugin/lib/openvpn-auth-pam.so /etc/pam.d/login[/COLOR]
client-cert-not-required
username-as-common-name
server 1.2.3.0 255.255.255.0
push "redirect-gateway def1"
push "dhcp-option DNS 208.67.222.222"
push "dhcp-option DNS 4.2.2.1"
keepalive 5 30
comp-lzo
persist-key
persist-tun
status 1194.log
verb 3

before you save the configuration, make sure that the "plugin /usr/share/.. /pam.d/login" is one line

Start the OPENVPN with 1194.conf
#openvpn /etc/openvpn/1194.conf &

here's the status if OPENVPN successfully started

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Mon Feb 21 02:23:20 2011 UDPv4 link remote: [undef]
Mon Feb 21 02:23:20 2011 MULTI: multi_init called, r=256 v=256
Mon Feb 21 02:23:20 2011 IFCONFIG POOL: base=1.2.3.4 size=62
Mon Feb 21 02:23:20 2011 Initialization Sequence Completed

Make OPENVPN 1194.conf running in background
#bg

Enable ipv4 forward
#echo 1 > /proc/sys/net/ipv4/ip_forward

Route iptables
#iptables -t nat -A POSTROUTING -s 1.2.3.0/24 -j SNAT --to 123.123.123.123

*1.2.3.0 is allocated ip for OPENVPN client
*123.123.123.123 is your server ip

Now we create username and password for authorization
#useradd username -s /bin/false
#passwd username

Download ca.crt file in /etc/openvpn/easy-rsa/2.0/keys/ directory, you can use sftp client

Download and install OPENVPN client for windows, download the latest stable release OPENVPN version 2.1.4 from here

After you finished installing OPENVPN, move ca.crt (file that you previously downloaded from /etc/openvpn/easy-rsa/2.0/keys/) to OPENVPN config folder in your program files (\Program Files\OpenVPN\config\)

Also create client configuration file in OPENVPN config directory, here's the example:

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client
dev tun
proto udp #- protocol
remote 123.123.123.123 1194 #- SERVER IP and OPENVPN Port
resolv-retry infinite
nobind
tun-mtu 1500
tun-mtu-extra 32
mssfix 1450
persist-key
persist-tun
ca ca.crt
auth-user-pass
comp-lzo
verb 3

save with anyname.ovpn or 1194.ovpn

http://i56.tinypic.com/aktvet.jpg

Run OPENVPN Client on your Windows, connect with your username and password.

http://i55.tinypic.com/2vwz9di.jpg
http://i53.tinypic.com/2883y0y.jpg

Check your IP Address in browser and Voila!!! You're IP is now changed to your server IP

note:
- Never fails make OPENVPN on CentOS with this tutorial
- Those configurations above are basic configuration, you can check OPENVPN website for another configuration
- If you're using Win 7, before installing OPENVPN client, right click on the installer, properties, run as administrator and change compatibility to Windows XP SP3
- If you wanna add another port, maybe TCP so you can run OPENVPN over proxy, just create new configuration for server, adjust the following lines:

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[B]port:[/B] your preferred port
[B]protocol:[/B] tcp or udp
[B]client's ip:[/B] 1.2.4.0 or 1.2.5.0 ; 1.2.6.0 ; and so on

also new configuration for client

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[B]proto xxxx[/B] #- change xxxx to tcp or udp
[B]remote 123.123.123.123 yyyy[/B] #- change yyyy to OPENVPN port

and then run the command
#iptables -t nat -A POSTROUTING -s 1.2.4.0/24 -j SNAT --to 123.123.123.123

Ref: Uncle G

My question is:
is this the command that is used to download and install openvpn?

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yum install openvpn

i don't see from there the http:// link to the openvpn installer. so how did it know where openvpn can be downloaded? And how do i change it if i want to use other older version?

[Bebop]

Debian is the easiest to install OpenVPN out of the box.

But since you have Centos already, there's just a couple of extra steps.

First: Install Epel repository OR Install Dag repository.

After you install one of those, "yum install openvpn" will work for you.

After this, type:

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cd /etc/openvpn

and you will be in the OpenVPN installation directory.

Also

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service openvpn stop
service openvpn start

Should give you some kind of output. Probably an error message if you have not edited the conf files yet.

old version.. sorry not sure how to downgrade. I think if you want old version, better uninstall new version, then install old version manually (rpm files).