# OpenVPN config help

## linuxpyro

OK, I posted earlier about having trouble starting OpenVPN from the init script.  Right now I'm testing it out on my client and server by using openvpn /path/to/config and am a bit confused about how to set things up.

I have set up a small LAN in my dorm, with the subnet 192.168.2.0/24.  Back home I have a Linksys router which uses a the subnet 192.168.1.0/24.  On the home subnet are a couple servers I would like to access, as well as some other hosts.  The server I am using for the Openvpn server is a file server with one nic which has the IP 192.168.1.10.  In my dorm I have a box set up as a router which currently connects my private LAN to the Internet.  I want to set this up as a client.  What I want to do is set up a link between these two, such that I can ping hosts on either subnet from the other, yet on my dorm LAN access the Internet through my dorm's connection.  I understand this is a matter of routing, but I am not sure how to go about setting this up in the config files.

The router I use in my dorm, which I want to use as the VPN client, has the internal IP 192.168.2.1.  With the OpenVPN client running, here is the routing table:

```

Kernel IP routing table

Destination     Gateway         Genmask         Flags Metric Ref    Use Iface

192.168.2.1     192.168.2.5     255.255.255.255 UGH   0      0        0 tun0

192.168.2.5     *               255.255.255.255 UH    0      0        0 tun0

129.21.109.0    *               255.255.255.128 U     0      0        0 eth0

192.168.2.0     *               255.255.255.0   U     0      0        0 eth1

192.168.1.0     192.168.2.5     255.255.255.0   UG    0      0        0 tun0

169.254.0.0     *               255.255.0.0     U     0      0        0 eth1

127.0.0.0       *               255.0.0.0       U     0      0        0 lo

default         rit-dorm1-gw-04 0.0.0.0         UG    0      0        0 eth0

```

Here is my server config, which is derived from the sample config:

```

#################################################

# 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

# 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 tap" if you are ethernet bridging.

# 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 tap

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 ca.crt

cert server.crt

key 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 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 192.168.2.0 255.255.255.0

# 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

# 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 192.168.1.0 255.255.255.0"

push "route 192.168.2.0 255.255.255.0"

# 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

# 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

# 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 openvpn

group openvpn

# 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 3

# Silence repeating messages.  At most 20

# sequential messages of the same message

# category will be output to the log.

;mute 20

```

And here is my client config:

```

port 1194 

proto udp

dev tun

remote 67.21.84.153

tls-client

cd /etc/openvpn/client

ca ca.crt

cert badger.crt

key badger.key

#tls-auth ta.key 1

mtu-test

tun-mtu 1500

tun-mtu-extra 32

mssfix 1450

pull

comp-lzo

verb 4

ns-cert-type server

```

Right now the two will connect without problem; I'm just having trouble getting the routing right.  Thanks for any insight.

----------

## thomateverte

hi,

did you follow the openvpn how to (http://openvpn.net/howto.html) ? it gives a lot of information about the two ways to set up a VPN (either bridged or routed) and what iptables rules to set up for the routing. I chose the bridged solution so i cannot help you a lot about routing. They say that the bridge solution is harder to set up because of the bridge setup. but in Gentoo, the bridge is really easy to setup, only a few lines in /etc/conf.d/net.

----------

## linuxpyro

I've been working with the OpenVPN howto for a while, I was hoping I could find someone with a similar situation.  I'd prefer to go with the routed setup, as I would like to keep my subnet set up the way it is.  Thanks for the reply, though.    :Very Happy: 

----------

## ticho

Hello,

 I used to run fairly complicated openvpn setup, not unlike yours - I had  four LANs connected to each other via openvpn, so that every box in every LAN could connect to any other box in any other LAN.

I've used a dedicated subnet for vpn - 10.0.0.0/24, and central openvpn server (router, which had one of the LANs behind it) was pushing all necessary routes to the clients (other routers with their LANs behind them).

If you're still interested, let me know, and I'll send you some config files, and/or we could meet up on IRC and debug in realtime.

Cheers.

----------

