linux bridge eth interface with openvpn and DHCP

rajeshku

Hi,

Can you please help me to bridge with DHCP in openVPN.I found the topic

http://openvpn.net/index.php/open-source/documentation/miscellaneous/76-ethernet-bridging.html

But it is for using client IP pool.I need to configure with DHCP.Any help will be appreciated.

Thanks

gladiatr72

This comes directly from the openvpn man page (which I'd recommend reading)

       --server-bridge ['nogw']

              A helper directive similar to --server which is designed to sim-
              plify the configuration of OpenVPN's  server  mode  in  ethernet
              bridging configurations.

              If  --server-bridge  is  used  without  any  parameters, it will
              enable a DHCP-proxy mode, where connecting OpenVPN clients  will
              receive an IP address for their TAP adapter from the DHCP server
              running on the OpenVPN server-side LAN.  Note that only  clients
              that  support  the binding of a DHCP client with the TAP adapter
              (such as Windows) can support this mode.  The optional nogw flag
              (advanced)  indicates  that  gateway  information  should not be
              pushed to the client.

rajeshku

Thanks for your reply.

I have OpenVPN installed and accepting connections from users.

What i need is eth1 to be bridged onto the VPN.

Also OpenVPN needs to be configured to assign IPs from a DHCP server, which has already been setup and configured on the same machine.

Can you please provide the steps ?
Thanks

gladiatr72

What OS are you using?

rajeshku

CentOS please give me a step by step instrestion asap.

Thanks

gladiatr72

To configure a your ethernet device for bridging in centos/rhel:

I'm assuming your internal ethernet device is eth1.

/etc/sysconfig/network-scripts/ifcfg-br0

DEVICE=br0
TYPE=Bridge
BOOTPROTO=static
IPADDR=[internal IP address]
NETMASK=255.255.255.0
ONBOOT=yes
USERCTL=yes
IPV6INIT=no
PEERDNS=no
PROMISC=yes

/etc/sysconfig/network-scripts/ifcfg-eth1

DEVICE=eth1
TYPE=Ethernet
USERCTL=yes
ONBOOT=yes
IPV6INIT=no
PEERDNS=no
BRIDGE=br0
PROMISC=yes

to add the tap device to the bridge, use the up directive in your openvpn server configuration as follows:

up /etc/openvpn/bridge-start.sh

/etc/openvpn/bridge-start.sh

#!/bin/bash

echo "adding $1 to bridge"

brctl addif br0 $1

ifconfig $1 up

chmod 755 /etc/openvpn/bridge-start.sh

rajeshku

Thank you very much for your reply.