Technical data
4. Packages
OPENVPN_DEFAULT_TUN_MTU='1500'
OPENVPN_DEFAULT_MSSFIX='1300'
OPENVPN_DEFAULT_FRAGMENT='1300'
For fli4l versions prior to 2.1.9 „tun-mtu“ parameters can’t be specified directly. But they
can be influenced indirectly with OPENVPN_x_LINK_MTU. tun-mtu values are about 45 byte smaller
than the values in OPENVPN_x_LINK_MTU. To get exact values only trying will help.
4.14.8. OpenVPN - Examples
Some examples will clarify the configuration of package OpenVPN.
Example - Joining Two Nets Using fli4l Routers
In the first example two fli4l routers will be connected. Nets behind each fli4l router should
gain access to each other. Peter and Maria want to connect their nets over their fli4l routers.
Peter uses a private net 192.168.145.0/24 and a DynDNS address ’peter.eisfair.net’. Marias
setup is similar while she is using 10.23.17.0/24 and DynDNS address ’maria.eisfair.net’. Both
trust in each other so they allow unlimited access to their complete nets for each other.
OpenVPN Option Peter Maria
OPENVPN_1_NAME= ’maria’ ’peter’
OPENVPN_1_REMOTE_HOST= ’maria.eisfair.net’ ’peter.eisfair.net’
OPENVPN_1_REMOTE_PORT= ’10000’ ’10001’
OPENVPN_1_LOCAL_PORT= ’10001’ ’10000’
OPENVPN_1_SECRET= ’pema.secret’ ’pema.secret’
OPENVPN_1_TYPE= ’tunnel’ ’tunnel’
OPENVPN_1_REMOTE_VPN_IP= ’192.168.200.202’ ’192.168.200.193’
OPENVPN_1_LOCAL_VPN_IP= ’192.168.200.193’ ’192.168.200.202’
OPENVPN_1_ROUTE_N= ’1’ ’1’
OPENVPN_1_ROUTE_1= ’10.23.17.0/24’ ’192.168.145.0/24’
OPENVPN_1_PF_INPUT_N= ’1’ ’1’
OPENVPN_1_PF_INPUT_1= ’ACCEPT’ ’ACCEPT’
OPENVPN_1_PF_FORWARD_N= ’1’ ’1’
OPENVPN_1_PF_FORWARD_1= ’ACCEPT’ ’ACCEPT’
Table 4.12.: OpenVPN Configuration with 2 fli4l routers
Example - Two Nets Connected By A Bridge
In the next example a bridge over a wi-fi connection will be configured. Packet filters are
not of use here because usually ethernet frames will be forwarded but no IP packets. Please
remember that with a bridge a common net is used. Thus no IP address can exist twice.
In addition to the settings for OpenVPN a bridge has to be configured in ad-
vanced_networking and base.txt has to be adapted to use the bridge device and not eth0
as the network device for the internal net. See the relevant entries in advanced_networking’s
and base’s configuration files:
Example - Configure Access For A Road Warrior
For this example (Roadwarrior) access to a LAN behind fli4l should be configured for a note-
book with Windows XP over GPRS. OpenVPN is installed on the notebook and the *.ovpn file
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