Overview
The first step in building an OpenVPN 2.x configuration is to establish a PKI (public key infrastructure). The PKI consists of:
- a separate certificate (also known as a public key) and private key for the server and each client, and
- a master Certificate Authority (CA) certificate and key which is used to sign each of the server and client certificates.
Router Setup as OpenVPN Server. Go to VPN and Remote Access OpenVPN General Setup and ensure that the configuration page matches the settings illustrated below. Go to the Client Config tab and specify the file name of CA Certificate, Client Certificate, and Client Key. Then, click Export. Access Server comes with a self-signed certificate for access immediately after launch, but this will bring up a security warning in your browser. This tutorial steps through how to replace it with your own, valid web certificate. What you’ll need: A certificate (we used one from Let’s Encrypt) A DNS record created.
OpenVPN supports bidirectional authentication based on certificates, meaning that the client must authenticate the server certificate and the server must authenticate the client certificate before mutual trust is established.
Both server and client will authenticate the other by first verifying that the presented certificate was signed by the master certificate authority (CA), and then by testing information in the now-authenticated certificate header, such as the certificate common name or certificate type (client or server).
This security model has a number of desirable features from the VPN perspective:
- The server only needs its own certificate/key — it doesn’t need to know the individual certificates of every client which might possibly connect to it.
- The server will only accept clients whose certificates were signed by the master CA certificate (which we will generate below). And because the server can perform this signature verification without needing access to the CA private key itself, it is possible for the CA key (the most sensitive key in the entire PKI) to reside on a completely different machine, even one without a network connection.
- If a private key is compromised, it can be disabled by adding its certificate to a CRL (certificate revocation list). The CRL allows compromised certificates to be selectively rejected without requiring that the entire PKI be rebuilt.
- The server can enforce client-specific access rights based on embedded certificate fields, such as the Common Name.
Note that the server and client clocks need to be roughly in sync or certificates might not work properly.
Generate the master Certificate Authority (CA) certificate & key
In this section we will generate a master CA certificate/key, a server certificate/key, and certificates/keys for 3 separate clients.
For PKI management, we will use easy-rsa 2, a set of scripts which is bundled with OpenVPN 2.2.x and earlier. If you’re using OpenVPN 2.3.x, you need to download easy-rsa 2 separately from here.
For PKI management, we will use easy-rsa 2, a set of scripts which is bundled with OpenVPN 2.2.x and earlier. If you’re using OpenVPN 2.3.x, you may need to download easy-rsa 2 separately from the easy-rsa-old project page. An easy-rsa 2 package is also available for Debian and Ubuntu in the OpenVPN software repos. On *NIX platforms you should look into using easy-rsa 3instead; refer to its own documentation for details.
If you are using Linux, BSD, or a unix-like OS, open a shell and cd to the easy-rsa subdirectory. If you installed OpenVPN from an RPM or DEB file, the easy-rsa directory can usually be found in /usr/share/doc/packages/openvpn or /usr/share/doc/openvpn(it’s best to copy this directory to another location such as /etc/openvpn, before any edits, so that future OpenVPN package upgrades won’t overwrite your modifications). If you installed from a .tar.gz file, the easy-rsa directory will be in the top level directory of the expanded source tree.
If you are using Windows, open up a Command Prompt window and cd to Program FilesOpenVPNeasy-rsa. Run the following batch file to copy configuration files into place (this will overwrite any preexisting vars.bat and openssl.cnf files):
Now edit the vars file (called vars.bat on Windows) and set the KEY_COUNTRY, KEY_PROVINCE, KEY_CITY, KEY_ORG, and KEY_EMAIL parameters. Don’t leave any of these parameters blank.
Next, initialize the PKI. On Linux/BSD/Unix:
On Windows:
![Access Access](https://chrisatech.files.wordpress.com/2017/07/letsencryptaccessserver.png?w=1400&h=9999)
The final command (build-ca) will build the certificate authority (CA) certificate and key by invoking the interactive opensslcommand:
Note that in the above sequence, most queried parameters were defaulted to the values set in the varsor vars.bat files. The only parameter which must be explicitly entered is the Common Name. In the example above, I used “OpenVPN-CA”.Generate certificate & key for serverNext, we will generate a certificate and private key for the server. On Linux/BSD/Unix: On Windows: As in the previous step, most parameters can be defaulted. When the Common Name is queried, enter “server”. Two other queries require positive responses, “Sign the certificate? [y/n]” and “1 out of 1 certificate requests certified, commit? [y/n]”. Generate certificates & keys for 3 clientsGenerating client certificates is very similar to the previous step. On Linux/BSD/Unix: On Windows: If you would like to password-protect your client keys, substitute the build-key-pass script. Remember that for each client, make sure to type the appropriate Common Name when prompted, i.e. “client1”, “client2”, or “client3”. Always use a unique common name for each client. Generate Diffie Hellman parametersDiffie Hellman parameters must be generated for the OpenVPN server. On Linux/BSD/Unix: On Windows: Output: |
Key FilesNow we will find our newly-generated keys and certificates in the keys subdirectory. Here is an explanation of the relevant files:
The final step in the key generation process is to copy all files to the machines which need them, taking care to copy secret files over a secure channel. Now wait, you may say. Shouldn’t it be possible to set up the PKI without a pre-existing secure channel? The answer is ostensibly yes. In the example above, for the sake of brevity, we generated all private keys in the same place. With a bit more effort, we could have done this differently. For example, instead of generating the client certificate and keys on the server, we could have had the client generate its own private key locally, and then submit a Certificate Signing Request (CSR) to the key-signing machine. In turn, the key-signing machine could have processed the CSR and returned a signed certificate to the client. This could have been done without ever requiring that a secret .key file leave the hard drive of the machine on which it was generated. |
OpenVPN is a Virtual Private Networking (VPN) solution provided in the Ubuntu Repositories. It is flexible, reliable and secure. It belongs to the family of SSL/TLS VPN stacks (different from IPSec VPNs). This chapter will cover installing and configuring OpenVPN to create a VPN.
If you want more than just pre-shared keys OpenVPN makes it easy to set up a Public Key Infrastructure (PKI) to use SSL/TLS certificates for authentication and key exchange between the VPN server and clients. OpenVPN can be used in a routed or bridged VPN mode and can be configured to use either UDP or TCP. The port number can be configured as well, but port 1194 is the official one; this single port is used for all communication. Doremisoft avchd converter for mac. Moborobo iphone. VPN client implementations are available for almost anything including all Linux distributions, OS X, Windows and OpenWRT based WLAN routers.
Server Installation
To install openvpn in a terminal enter:
Public Key Infrastructure Setup
The first step in building an OpenVPN configuration is to establish a PKI (public key infrastructure). The PKI consists of:
- a separate certificate (also known as a public key) and private key for the server and each client.
- a master Certificate Authority (CA) certificate and key, used to sign the server and client certificates.
OpenVPN supports bidirectional authentication based on certificates, meaning that the client must authenticate the server certificate and the server must authenticate the client certificate before mutual trust is established.
Both server and client will authenticate the other by first verifying that the presented certificate was signed by the master certificate authority (CA), and then by testing information in the now-authenticated certificate header, such as the certificate common name or certificate type (client or server).
Certificate Authority Setup
To setup your own Certificate Authority (CA) and generate certificates and keys for an OpenVPN server and multiple clients first copy the
easy-rsa
directory to /etc/openvpn
. This will ensure that any changes to the scripts will not be lost when the package is updated. From a terminal, run:Note: If desired, you can alternatively edit
/etc/openvpn/easy-rsa/vars
directly, adjusting it to your needs.As
root
user change to the newly created directory /etc/openvpn/easy-rsa
and run:Server Keys and Certificates
Next, we will generate a key pair for the server:
Diffie Hellman parameters must be generated for the OpenVPN server. The following will place them in
pki/dh.pem
.And finally a certificate for the server:
Install exile mod arma 3. All certificates and keys have been generated in subdirectories. Common practice is to copy them to /etc/openvpn/:
Client Certificates
The VPN client will also need a certificate to authenticate itself to the server. Usually you create a different certificate for each client.
This can either be done on the server (as the keys and certificates above) and then securely distributed to the client. Or vice versa: the client can generate and submit a request that is sent and signed by the server.
To create the certificate, enter the following in a terminal while being user root:
If the first command above was done on a remote system, then copy the .req file to the CA server. There you can then import it via
easyrsa import-req /incoming/myclient1.req myclient1
. Then you can go on with the second sign-eq
command.In both cases, afterwards copy the following files to the client using a secure method:
pki/ca.crt
pki/issued/myclient1.crt
As the client certificates and keys are only required on the client machine, you can remove them from the server.
Simple Server Configuration
Along with your OpenVPN installation you got these sample config files (and many more if you check):
Stihl ts 360 repair manual. Start with copying and unpacking server.conf.gz to /etc/openvpn/server.conf.
Edit
/etc/openvpn/myserver.conf
to make sure the following lines are pointing to the certificates and keys you created in the section above.Complete this set with a ta key in
etc/openvpn
for tls-auth like:Edit
/etc/sysctl.conf
and uncomment the following line to enable IP forwarding.Putty mac. Then reload sysctl.
That is the minimum you have to configure to get a working OpenVPN server. You can use all the default settings in the sample server.conf file. Now start the server.
Be aware that the “systemctl start openvpn” is not starting your openvpn you just defined.
Openvpn uses templatized systemd jobs, openvpn@CONFIGFILENAME. So if for example your configuration file is
Openvpn uses templatized systemd jobs, openvpn@CONFIGFILENAME. So if for example your configuration file is
myserver.conf
your service is called openvpn@myserver. You can run all kinds of service and systemctl commands like start/stop/enable/disable/preset against a templatized service like openvpn@server.You will find logging and error messages in the journal. Resident revelations 2 pc download. For example, if you started a templatized service openvpn@server you can filter for this particular message source with:
The same templatized approach works for all of systemctl:
You can enable/disable various openvpn services on one system, but you could also let Ubuntu do it for you. There is config for
AUTOSTART
in /etc/default/openvpn
. Allowed values are “all”, “none” or space separated list of names of the VPNs. If empty, “all” is assumed. The VPN name refers to the VPN configutation file name. i.e. home
would be /etc/openvpn/home.conf
If you’re running systemd, changing this variable will require running systemctl daemon-reload
followed by a restart of the openvpn service (if you removed entries you may have to stop those manually).After “systemctl daemon-reload” a restart of the “generic” openvpn will restart all dependent services that the generator in /lib/systemd/system-generators/openvpn-generator created for your conf files when you called daemon-reload.
Now check if OpenVPN created a tun0 interface:
Simple Client Configuration
There are various different OpenVPN client implementations with and without GUIs. You can read more about clients in a later section on VPN Clients. For now we use commandline/service based OpenVPN client for Ubuntu which is part of the very same package as the server. So you have to install the
openvpn
package again on the client machine:This time copy the client.conf sample config file to /etc/openvpn/:
Copy the following client keys and certificate files you created in the section above to e.g. /etc/openvpn/ and edit
/etc/openvpn/client.conf
to make sure the following lines are pointing to those files. If you have the files in /etc/openvpn/ you can omit the path.And you have to specify the OpenVPN server name or address. Make sure the keyword client is in the config. That’s what enables client mode.
Now start the OpenVPN client with the same templatized mechanism:
You can check status as you did on the server:
On the server log an incoming connection looks like the following.
You can see client name and source address as well as success/failure messages.
You can see client name and source address as well as success/failure messages.
And you can check on the client if it created a tun0 interface:
Check if you can ping the OpenVPN server:
Note
The OpenVPN server always uses the first usable IP address in the client network and only that IP is pingable. E.g. if you configured a /24 for the client network mask, the .1 address will be used. The P-t-P address you see in the
ip addr
output above is usually not answering ping requests.Check out your routes:
First trouble shooting
If the above didn’t work for you, check this:
- Check your
journal -xe
- Check that you have specified the keyfile names correctly in client and server conf files
- Can the client connect to the server machine? Maybe a firewall is blocking access? Check journal on server.
- Client and server must use same protocol and port, e.g. UDP port 1194, see port and proto config option
- Client and server must use same config regarding compression, see comp-lzo config option
- Client and server must use same config regarding bridged vs routed mode, see server vs server-bridge config option
Advanced configuration
Advanced routed VPN configuration on server
The above is a very simple working VPN. The client can access services on the VPN server machine through an encrypted tunnel. If you want to reach more servers or anything in other networks, push some routes to the clients. E.g. if your company’s network can be summarized to the network 192.168.0.0/16, you could push this route to the clients. But you will also have to change the routing for the way back - your servers need to know a route to the VPN client-network.
The example config files that we have been using in this guide are full of all these advanced options in the form of a comment and a disabled configuration line as an example.
Note
Please read the OpenVPN hardening security guide for further security advice.
Advanced bridged VPN configuration on server
OpenVPN can be setup for either a routed or a bridged VPN mode. Sometimes this is also referred to as OSI layer-2 versus layer-3 VPN. In a bridged VPN all layer-2 frames - e.g. all ethernet frames - are sent to the VPN partners and in a routed VPN only layer-3 packets are sent to VPN partners. In bridged mode all traffic including traffic which was traditionally LAN-local like local network broadcasts, DHCP requests, ARP requests etc. are sent to VPN partners whereas in routed mode this would be filtered.
Openvpn Access Server Free
Prepare interface config for bridging on server
First, use netplan to configure a bridge device using the desired ethernet device.
Openvpn Access Server Certificates
Static IP addressing is highly suggested. DHCP addressing can also work, but you will still have to encode a static address in the OpenVPN configuration file.
The next step on the server is to configure the ethernet device for promiscuous mode on boot. To do this, ensure the networkd-dispatcher package is installed and create the following configuration script.
Then add the following contents.
Prepare server config for bridging
Edit
/etc/openvpn/server.conf
to use tap rather than tun and set the server to use the server-bridge directive:After configuring the server, restart openvpn by entering:
Update Openvpn Access Server
Prepare client config for bridging
The only difference on the client side for bridged mode to what was outlined above is that you need to edit
/etc/openvpn/client.conf
and set tap
mode:Finally, restart openvpn:
You should now be able to connect to the full remote LAN through the VPN.
Openvpn Access Server Change Certificate
References
Openvpn Access Server Download Certificates
- Snap’ed version of openvpn easy-openvpn
- Debians OpenVPN Guide