Openvpn Does Server Generate Keys For Clients
Introduction
Static key configurations offer the simplest setup, and are ideal for point-to-point VPNs or proof-of-concept testing.
Static Key advantages
- Simple Setup
- No X509 PKI (Public Key Infrastructure) to maintain
Static Key disadvantages
- Limited scalability — one client, one server
- Lack of perfect forward secrecy — key compromise results in total disclosure of previous sessions
- Secret key must exist in plaintext form on each VPN peer
- Secret key must be exchanged using a pre-existing secure channel
This guide covers how to create certificates and keys for OpenVPN server and clients using the EasyRSA tool on MacOS. The instructions are very similar for most flavours of linux such as Ubuntu once the correct packages are installed (e.g. On Ubuntu: apt-get install openvpn easy-rsa). A master Certificate Authority (CA) certificate and key which is used to sign each of 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.
- Home; VPN Server. With VPN connection, you can set up multiple VPN clients to access Yeastar S-Series VoIP PBX securely. OpenVPN Certificates and Keys. Before you start to set up the OpenVPN network, you need to make the related certificates and keys for VPN server and VPN clients.
- Aug 22, 2016 Generating certificates for new clients. I installed OpenVPN on a Ubuntu machine, and generated certificates to allow another Linux client to connect. Verified it's working, and the client is forced to use the VPN tunnel. In the example I followed, the server certs (including the DH pem file) were moved to /etc/openvpn.
Simple Example
This example demonstrates a bare-bones point-to-point OpenVPN configuration. A VPN tunnel will be created with a server endpoint of 10.8.0.1 and a client endpoint of 10.8.0.2. Encrypted communication between client and server will occur over UDP port 1194, the default OpenVPN port.
OpenVPN to be run from a non-administrator account. OpenVPN to be started automatically on system startup. This is often preferred on the server machine, as well as any machines which will be constantly connected to the server. Run the Windows Service administrative tool: Press Windows Key + R Type 'services.msc'. Generating OpenVPN keys using Easy RSA. It is possible to generate your certificates on the router itself if you don't have access to a Linux machine, or if you don't have a Windows client installed with Easy-RSA. Easy-RSA is a simple to use environment that is bundled with OpenVPN, and has been included in Asuswrt-Merlin.
Generate a static key:
Copy the static key to both client and server, over a pre-existing secure channel.
Server configuration file
Client configuration file
Firewall configuration
Anno 1701 cd key generator. Make sure that:
- UDP port 1194 is open on the server, and
- the virtual TUN interface used by OpenVPN is not blocked on either the client or server (on Linux, the TUN interface will probably be called tun0 while on Windows it will probably be called something like Local Area Connection n unless you rename it in the Network Connections control panel).
Bear in mind that 90% of all connection problems encountered by new OpenVPN users are firewall-related.
Testing the VPN
Run OpenVPN using the respective configuration files on both server and client, changing myremote.mydomain in the client configuration to the domain name or public IP address of the server.
To verify that the VPN is running, you should be able to ping 10.8.0.2 from the server and 10.8.0.1 from the client.
Expanding on the Simple Example
Use compression on the VPN link
Add the following line to both client and server configuration files:
Make the link more resistent to connection failures
Deal with:
- keeping a connection through a NAT router/firewall alive, and
- follow the DNS name of the server if it changes its IP address.
Add the following to both client and server configuration files:
Run OpenVPN as a daemon (Linux/BSD/Solaris/MacOSX only)
Run OpenVPN as a daemon and drop privileges to user/group nobody.
Add to configuration file (client and/or server):
Generate Openvpn File
Allow client to reach entire server subnet
Suppose the OpenVPN server is on a subnet 192.168.4.0/24. Add the following to client configuration:
Then on the server side, add a route to the server’s LAN gateway that routes 10.8.0.2 to the OpenVPN server machine (only necessary if the OpenVPN server machine is not also the gateway for the server-side LAN). Also, don’t forget to enable IP Forwarding on the OpenVPN server machine.
Getting the sample config files
It’s best to use the OpenVPN sample configuration files as a starting point for your own configuration. These files can also be found in
- the sample-config-files directory of the OpenVPN source distribution
- the sample-config-files directory in /usr/share/doc/packages/openvpn or /usr/share/doc/openvpn if you installed from an RPM or DEB package
- Start Menu -> All Programs -> OpenVPN -> OpenVPN Sample Configuration Files on Windows
Note that on Linux, BSD, or unix-like OSes, the sample configuration files are named server.conf and client.conf. On Windows they are named server.ovpn and client.ovpn.
Editing the server configuration file
The sample server configuration file is an ideal starting point for an OpenVPN server configuration. It will create a VPN using a virtual TUN network interface (for routing), will listen for client connections on UDP port 1194 (OpenVPN’s official port number), and distribute virtual addresses to connecting clients from the 10.8.0.0/24 subnet.
Before you use the sample configuration file, you should first edit the ca, cert, key, and dh parameters to point to the files you generated in the PKI section above.
At this point, the server configuration file is usable, however you still might want to customize it further:
- If you are using Ethernet bridging, you must use server-bridge and dev tap instead of server and dev tun.
- If you want your OpenVPN server to listen on a TCP port instead of a UDP port, use proto tcpinstead of proto udp (If you want OpenVPN to listen on both a UDP and TCP port, you must run two separate OpenVPN instances).
- If you want to use a virtual IP address range other than 10.8.0.0/24, you should modify the serverdirective. Remember that this virtual IP address range should be a private range which is currently unused on your network.
- Uncomment out the client-to-client directive if you would like connecting clients to be able to reach each other over the VPN. By default, clients will only be able to reach the server.
- If you are using Linux, BSD, or a Unix-like OS, you can improve security by uncommenting out the user nobody and group nobody directives.
If you want to run multiple OpenVPN instances on the same machine, each using a different configuration file, it is possible if you:
- Use a different port number for each instance (the UDP and TCP protocols use different port spaces so you can run one daemon listening on UDP-1194 and another on TCP-1194).
- If you are using Windows, each OpenVPN configuration taneeds to have its own TAP-Windows adapter. You can add additional adapters by going to Start Menu -> All Programs -> TAP-Windows -> Add a new TAP-Windows virtual ethernet adapter.
- If you are running multiple OpenVPN instances out of the same directory, make sure to edit directives which create output files so that multiple instances do not overwrite each other’s output files. These directives include log, log-append, status, and ifconfig-pool-persist.
Editing the client configuration files
Openvpn Client Mac
The sample client configuration file (client.conf on Linux/BSD/Unix or client.ovpn on Windows) mirrors the default directives set in the sample server configuration file.
Openvpn Server List
- Like the server configuration file, first edit the ca, cert, and key parameters to point to the files you generated in the PKI section above. Note that each client should have its own cert/key pair. Only the cafile is universal across the OpenVPN server and all clients.
- Next, edit the remotedirective to point to the hostname/IP address and port number of the OpenVPN server (if your OpenVPN server will be running on a single-NIC machine behind a firewall/NAT-gateway, use the public IP address of the gateway, and a port number which you have configured the gateway to forward to the OpenVPN server).
- Finally, ensure that the client configuration file is consistent with the directives used in the server configuration. The major thing to check for is that the dev (tun or tap) and proto (udp or tcp) directives are consistent. Also make sure that comp-lzo and fragment, if used, are present in both client and server config files.