OpenVPN server install and config the bridge on Fedora 10

Transfered from my journal.

Note: It is easy to install and config OpenVPN server on Windows XP. We should remember add the bridge (桥接) between the local network interface and the virtual network interface.

Official document:
OpenVPN 2.0 HOWTO
Ethernet Bridging

Useful document:
OpenVPN—-桥接
常见问题
1.拨通vpn后ping不通vpn server的内网ip
原因：server.conf中dev 配置有问题
解决方案：将dev tap设置为dev tap0
2.各个vpn客户端之间不能互通
原因：server.conf中client-to-client配置没有打开
解决方案：将此项加入到server.conf中

Required package:
bridge-utils rpm build for : Fedora 10
Content of RPM :
/usr/sbin/brctl
/usr/share/doc/bridge-utils-1.2
/usr/share/doc/bridge-utils-1.2/AUTHORS
/usr/share/doc/bridge-utils-1.2/COPYING
/usr/share/doc/bridge-utils-1.2/FAQ
/usr/share/doc/bridge-utils-1.2/HOWTO
/usr/share/man/man8/brctl.8.gz

System environment:

#> uname -a
Linux frontend 2.6.27.5-117.fc10.i686 #1 SMP Tue Nov 18 12:19:59 EST 2008 i686 i686 i386 GNU/Linux

#> ifconfig -a
eth0 Link encap:Ethernet HWaddr 00:13:72:40:26:7F
inet addr:10.4.3.17 Bcast:10.4.3.255 Mask:255.255.255.0
inet6 addr: fe80::213:72ff:fe40:267f/64 Scope:Link
UP BROADCAST RUNNING PROMISC MULTICAST MTU:1500 Metric:1
RX packets:51999 errors:0 dropped:0 overruns:0 frame:0
TX packets:15652 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:100
RX bytes:5051569 (4.8 MiB) TX bytes:1757669 (1.6 MiB)

eth1 Link encap:Ethernet HWaddr 00:13:72:40:26:80
inet addr:192.168.100.17 Bcast:192.168.100.255 Mask:255.255.255.0
inet6 addr: fe80::213:72ff:fe40:2680/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:5747 errors:0 dropped:0 overruns:0 frame:0
TX packets:2340 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:470066 (459.0 KiB) TX bytes:253434 (247.4 KiB)

lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:16436 Metric:1
RX packets:491 errors:0 dropped:0 overruns:0 frame:0
TX packets:491 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:130767 (127.7 KiB) TX bytes:130767 (127.7 KiB)

#> route -n
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
192.168.100.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0
10.4.3.0 0.0.0.0 255.255.255.0 U 0 0 0 eth1
169.254.0.0 0.0.0.0 255.255.0.0 U 1002 0 0 eth1
169.254.0.0 0.0.0.0 255.255.0.0 U 1003 0 0 eth0
192.168.0.0 192.168.100.254 255.255.0.0 UG 0 0 0 eth0
0.0.0.0 10.4.3.1 0.0.0.0 UG 0 0 0 eth1

Installed configuration:

#> cat /etc/rc.d/rc.local
# Start OpenVPN service
/etc/openvpn/bridge-start
/sbin/service openvpn start
# Add route
route add -net 192.168.0.0 netmask 255.255.0.0 gw 192.168.100.254 eth1
#route add default gw 10.4.3.1 eth0
route add default gw 10.4.3.1 br0
Note 1:
We should add the default gateway after we started the OpenVPN server, the bridge-start script will clear the default gateway.
Note2:
The default route should changed to br0 not eth0 – the bridged interface.

#> ifconfig -a
br0 Link encap:Ethernet HWaddr 00:13:72:40:26:7F
inet addr:10.4.3.17 Bcast:10.4.3.255 Mask:255.255.255.0
inet6 addr: fe80::213:72ff:fe40:267f/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:48639 errors:0 dropped:0 overruns:0 frame:0
TX packets:15365 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:4152487 (3.9 MiB) TX bytes:1727401 (1.6 MiB)

eth0 Link encap:Ethernet HWaddr 00:13:72:40:26:7F
inet addr:10.4.3.17 Bcast:10.4.3.255 Mask:255.255.255.0
inet6 addr: fe80::213:72ff:fe40:267f/64 Scope:Link
UP BROADCAST RUNNING PROMISC MULTICAST MTU:1500 Metric:1
RX packets:51999 errors:0 dropped:0 overruns:0 frame:0
TX packets:15652 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:100
RX bytes:5051569 (4.8 MiB) TX bytes:1757669 (1.6 MiB)

eth1 Link encap:Ethernet HWaddr 00:13:72:40:26:80
inet addr:192.168.100.17 Bcast:192.168.100.255 Mask:255.255.255.0
inet6 addr: fe80::213:72ff:fe40:2680/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:5747 errors:0 dropped:0 overruns:0 frame:0
TX packets:2340 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:470066 (459.0 KiB) TX bytes:253434 (247.4 KiB)

lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:16436 Metric:1
RX packets:491 errors:0 dropped:0 overruns:0 frame:0
TX packets:491 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:130767 (127.7 KiB) TX bytes:130767 (127.7 KiB)

tap0 Link encap:Ethernet HWaddr AE:11:02:37:F7:88
inet6 addr: fe80::ac11:2ff:fe37:f788/64 Scope:Link
UP BROADCAST RUNNING PROMISC MULTICAST MTU:1500 Metric:1
RX packets:301 errors:0 dropped:0 overruns:0 frame:0
TX packets:34402 errors:0 dropped:17 overruns:0 carrier:0
collisions:0 txqueuelen:100
RX bytes:30484 (29.7 KiB) TX bytes:3010000 (2.8 MiB)

#> route -n
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
192.168.100.0 0.0.0.0 255.255.255.0 U 0 0 0 eth1
10.4.3.0 0.0.0.0 255.255.255.0 U 0 0 0 br0
10.4.3.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0
169.254.0.0 0.0.0.0 255.255.0.0 U 1002 0 0 eth0
169.254.0.0 0.0.0.0 255.255.0.0 U 1003 0 0 eth1
192.168.0.0 192.168.100.254 255.255.0.0 UG 0 0 0 eth1
0.0.0.0 10.4.3.1 0.0.0.0 UG 0 0 0 br0

#> ls /etc/openvpn
bridge-start sample-keys
bridge-stop server.conf

#> cat /etc/openvpn/bridge-start
#!/bin/bash

#################################
# Set up Ethernet bridge on Linux
# Requires: bridge-utils
#################################

# Define Bridge Interface
br=”br0″

# Define list of TAP interfaces to be bridged,
# for example tap=”tap0 tap1 tap2″.
tap=”tap0″

# Define physical ethernet interface to be bridged
# with TAP interface(s) above.
eth=”eth0″
eth_ip=”10.4.3.17″
eth_netmask=”255.255.255.0″
eth_broadcast=”10.4.3.255″

for t in $tap; do
openvpn –mktun –dev $t
done

brctl addbr $br
brctl addif $br $eth

for t in $tap; do
brctl addif $br $t
done

for t in $tap; do
ifconfig $t 0.0.0.0 promisc up
done

ifconfig $eth 0.0.0.0 promisc up

ifconfig $br $eth_ip netmask $eth_netmask broadcast $eth_broadcast

#> cat /etc/openvpn/bridge-stop
#!/bin/bash

####################################
# Tear Down Ethernet bridge on Linux
####################################

# Define Bridge Interface
br=”br0″

# Define list of TAP interfaces to be bridged together
tap=”tap0″

ifconfig $br down
brctl delbr $br

for t in $tap; do
openvpn –rmtun –dev $t
done

#> cat /etc/openvpn/server.conf
#################################################
# Sample OpenVPN 2.0 config file for #
# multi-client server. #
# #
# This file is for the server side #
# of a many-clients <-> one-server #
# OpenVPN configuration. #
# #
# OpenVPN also supports #
# single-machine <-> single-machine #
# configurations (See the Examples page #
# on the web site for more info). #
# #
# This config should work on Windows #
# or Linux/BSD systems. Remember on #
# Windows to quote pathnames and use #
# double backslashes, e.g.: #
# “C:\\Program Files\\OpenVPN\\config\\foo.key” #
# #
# Comments are preceded with ‘#’ or ‘;’ #
#################################################

# Which local IP address should OpenVPN
# listen on? (optional)
;local a.b.c.d

# Which TCP/UDP port should OpenVPN listen on?
# If you want to run multiple OpenVPN instances
# on the same machine, use a different port
# number for each one. You will need to
# open up this port on your firewall.
port 1194
;port 5000

# TCP or UDP server?
;proto tcp
proto udp

# “dev tun” will create a routed IP tunnel,
# “dev tap” will create an ethernet tunnel.
# Use “dev tap0″ if you are ethernet bridging
# and have precreated a tap0 virtual interface
# and bridged it with your ethernet interface.
# If you want to control access policies
# over the VPN, you must create firewall
# rules for the the TUN/TAP interface.
# On non-Windows systems, you can give
# an explicit unit number, such as tun0.
# On Windows, use “dev-node” for this.
# On most systems, the VPN will not function
# unless you partially or fully disable
# the firewall for the TUN/TAP interface.
dev tap0
;dev tun

# Windows needs the TAP-Win32 adapter name
# from the Network Connections panel if you
# have more than one. On XP SP2 or higher,
# you may need to selectively disable the
# Windows firewall for the TAP adapter.
# Non-Windows systems usually don’t need this.
;dev-node MyTap

# SSL/TLS root certificate (ca), certificate
# (cert), and private key (key). Each client
# and the server must have their own cert and
# key file. The server and all clients will
# use the same ca file.
#
# See the “easy-rsa” directory for a series
# of scripts for generating RSA certificates
# and private keys. Remember to use
# a unique Common Name for the server
# and each of the client certificates.
#
# Any X509 key management system can be used.
# OpenVPN can also use a PKCS #12 formatted key file
# (see “pkcs12″ directive in man page).
ca sample-keys/tmp-ca.crt
cert sample-keys/server.crt
key sample-keys/server.key # This file should be kept secret

# Diffie hellman parameters.
# Generate your own with:
# openssl dhparam -out dh1024.pem 1024
# Substitute 2048 for 1024 if you are using
# 2048 bit keys.
dh sample-keys/dh1024.pem

# Configure server mode and supply a VPN subnet
# for OpenVPN to draw client addresses from.
# The server will take 10.8.0.1 for itself,
# the rest will be made available to clients.
# Each client will be able to reach the server
# on 10.8.0.1. Comment this line out if you are
# ethernet bridging. See the man page for more info.
;server 10.8.0.0 255.255.255.0

# Maintain a record of client <-> virtual IP address
# associations in this file. If OpenVPN goes down or
# is restarted, reconnecting clients can be assigned
# the same virtual IP address from the pool that was
# previously assigned.
;ifconfig-pool-persist ipp.txt

# Configure server mode for ethernet bridging.
# You must first use your OS’s bridging capability
# to bridge the TAP interface with the ethernet
# NIC interface. Then you must manually set the
# IP/netmask on the bridge interface, here we
# assume 10.8.0.4/255.255.255.0. Finally we
# must set aside an IP range in this subnet
# (start=10.8.0.50 end=10.8.0.100) to allocate
# to connecting clients. Leave this line commented
# out unless you are ethernet bridging.
;server-bridge 10.8.0.4 255.255.255.0 10.8.0.50 10.8.0.100
server-bridge 10.4.3.17 255.255.0.0 10.4.3.221 10.4.3.230

# Push routes to the client to allow it
# to reach other private subnets behind
# the server. Remember that these
# private subnets will also need
# to know to route the OpenVPN client
# address pool (10.8.0.0/255.255.255.0)
# back to the OpenVPN server.
;push “route 192.168.10.0 255.255.255.0″
;push “route 192.168.20.0 255.255.255.0″
push “route 10.4.0.0 255.255.0.0 10.4.3.1″

# To assign specific IP addresses to specific
# clients or if a connecting client has a private
# subnet behind it that should also have VPN access,
# use the subdirectory “ccd” for client-specific
# configuration files (see man page for more info).

# EXAMPLE: Suppose the client
# having the certificate common name “Thelonious”
# also has a small subnet behind his connecting
# machine, such as 192.168.40.128/255.255.255.248.
# First, uncomment out these lines:
;client-config-dir ccd
;route 192.168.40.128 255.255.255.248
# Then create a file ccd/Thelonious with this line:
# iroute 192.168.40.128 255.255.255.248
# This will allow Thelonious’ private subnet to
# access the VPN. This example will only work
# if you are routing, not bridging, i.e. you are
# using “dev tun” and “server” directives.

# EXAMPLE: Suppose you want to give
# Thelonious a fixed VPN IP address of 10.9.0.1.
# First uncomment out these lines:
;client-config-dir ccd
;route 10.9.0.0 255.255.255.252
# Then add this line to ccd/Thelonious:
# ifconfig-push 10.9.0.1 10.9.0.2

# Suppose that you want to enable different
# firewall access policies for different groups
# of clients. There are two methods:
# (1) Run multiple OpenVPN daemons, one for each
# group, and firewall the TUN/TAP interface
# for each group/daemon appropriately.
# (2) (Advanced) Create a script to dynamically
# modify the firewall in response to access
# from different clients. See man
# page for more info on learn-address script.
;learn-address ./script

# If enabled, this directive will configure
# all clients to redirect their default
# network gateway through the VPN, causing
# all IP traffic such as web browsing and
# and DNS lookups to go through the VPN
# (The OpenVPN server machine may need to NAT
# the TUN/TAP interface to the internet in
# order for this to work properly).
# CAVEAT: May break client’s network config if
# client’s local DHCP server packets get routed
# through the tunnel. Solution: make sure
# client’s local DHCP server is reachable via
# a more specific route than the default route
# of 0.0.0.0/0.0.0.0.
;push “redirect-gateway”

# Certain Windows-specific network settings
# can be pushed to clients, such as DNS
# or WINS server addresses. CAVEAT:
# http://openvpn.net/faq.html#dhcpcaveats
;push “dhcp-option DNS 10.8.0.1″
;push “dhcp-option WINS 10.8.0.1″

# Uncomment this directive to allow different
# clients to be able to “see” each other.
# By default, clients will only see the server.
# To force clients to only see the server, you
# will also need to appropriately firewall the
# server’s TUN/TAP interface.
;client-to-client
client-to-client

# Uncomment this directive if multiple clients
# might connect with the same certificate/key
# files or common names. This is recommended
# only for testing purposes. For production use,
# each client should have its own certificate/key
# pair.
#
# IF YOU HAVE NOT GENERATED INDIVIDUAL
# CERTIFICATE/KEY PAIRS FOR EACH CLIENT,
# EACH HAVING ITS OWN UNIQUE “COMMON NAME”,
# UNCOMMENT THIS LINE OUT.
;duplicate-cn
duplicate-cn

# The keepalive directive causes ping-like
# messages to be sent back and forth over
# the link so that each side knows when
# the other side has gone down.
# Ping every 10 seconds, assume that remote
# peer is down if no ping received during
# a 120 second time period.
keepalive 10 120

# For extra security beyond that provided
# by SSL/TLS, create an “HMAC firewall”
# to help block DoS attacks and UDP port flooding.
#
# Generate with:
# openvpn –genkey –secret ta.key
#
# The server and each client must have
# a copy of this key.
# The second parameter should be ’0′
# on the server and ’1′ on the clients.
;tls-auth ta.key 0 # This file is secret

# Select a cryptographic cipher.
# This config item must be copied to
# the client config file as well.
;cipher BF-CBC # Blowfish (default)
;cipher AES-128-CBC # AES
;cipher DES-EDE3-CBC # Triple-DES

# Enable compression on the VPN link.
# If you enable it here, you must also
# enable it in the client config file.
comp-lzo

# The maximum number of concurrently connected
# clients we want to allow.
;max-clients 100

# It’s a good idea to reduce the OpenVPN
# daemon’s privileges after initialization.
#
# You can uncomment this out on
# non-Windows systems.
user nobody
group nobody

# The persist options will try to avoid
# accessing certain resources on restart
# that may no longer be accessible because
# of the privilege downgrade.
persist-key
persist-tun

# Output a short status file showing
# current connections, truncated
# and rewritten every minute.
status openvpn-status.log

# By default, log messages will go to the syslog (or
# on Windows, if running as a service, they will go to
# the “\Program Files\OpenVPN\log” directory).
# Use log or log-append to override this default.
# “log” will truncate the log file on OpenVPN startup,
# while “log-append” will append to it. Use one
# or the other (but not both).
;log openvpn.log
;log-append openvpn.log

# Set the appropriate level of log
# file verbosity.
#
# 0 is silent, except for fatal errors
# 4 is reasonable for general usage
# 5 and 6 can help to debug connection problems
# 9 is extremely verbose
verb 4

# Silence repeating messages. At most 20
# sequential messages of the same message
# category will be output to the log.
;mute 20