This is part of my privacy series. Main post is here.
I haven’t written about steps 1 or 2 yet. Step 1 is fairly easy: get a server. Right now, I have a VPS through 1and1 (the same company that currently hosts maxsons.org)
Step 2 doesn’t make sense on a vps with limited disk space. Although, part of me says I should try. But, it may be easier with real disks so I’m planning to wait.
This is what I did to get OpenVPN installed and working. YMMV.
Text in the Courrier New font is what you should type in.
Text in the Comic Sans MS font is output.
Text in italics are notes.
No, I’m not going to show you how to SSH into your server, install putty, or use the command line ssh. Go google those things. Ask if you need help (I won’t not help) but I consider those things prerequisites for this howto.
- Since this is a new server, I ran “yum update” to make sure my server was up to date. It was.
- I ran the command “passwd” and set the password for the root user to something strong
- run “cat /dev/net/tun” to make sure that my vps supported TUN (required for openVPN). If this command returns “cat: /dev/net/tun: File descriptor in bad state” if TUN is supported.
- “yum install nano” . Yum is a text editor on linux. You can use anything you like. The guides I reference below do all the installs at once with a -y at the end. I don’t trust computers (and you shouldn’t either). Read the output, make sure they are doing what you want and you understand what is going on!
- “yum install openssl” You need this package as a prerequisite for openVPN
- “yum install lzo” another prerequisite for openVPN
- “yum install pam” yet another prereq
- At this point, I thought I could find an up-to-date rpm for openVPN and install it. I only was installing the minimum I needed (or thought I needed). I futzed around for a while here trying to find a binary and get it installed. No luck. I also futzed around adding some yum repositories to my config. I did sort of succede in getting a binary…but I kept getting an error: Requires: libpkcs11-helper.so.1 I fiddle-farted around for a bit trying to solve that on it’s own.
- “yum install gcc make rpm-build autoconf.noarch zlib-devel pam-devel openssl-devel” this command installs gcc; make; rpm-build; dev tools for zlib, pam, and openssl; along with autoconf. This is a bunch of dev tools I was trying to avoid installing by simply getting binaries.
- “wget http://openvpn.net/release/lzo-1.08-4.rf.src.rpm” this is a binary for lzo from openVPN
- “wget http://pkgs.repoforge.org/rpmforge-release/rpmforge-release-0.5.2-2.el6.rf.x86_64.rpm” I have no idea but the instructions I was following said I needed it.
- “rpmbuild –rebuild lzo-1.08-4.rf.src.rpm” this rebuilds the lzo binary I downloaded earlier.
- “rpm -Uvh lzo-*.rpm” this installs the lzo binaries
- “rpm -Uvh rpmforge-release*” this installs the rpm downloaded from rpmforge above
- “yum install openvpn” — finally we get to install openVPN
- I ended up and got openVPN 2.3.2 which differs from 2.2.2 and earlier in a significant way: it doesn’t include the easy-rsa application used to generate keys.
- “yum install easy-rsa” will install this. If you get an error, you’ll probably need to run steps 18, 19, and 20
- “cd /etc/yum.repos.d“
- “wget http://repos.openvpn.net/repos/yum/conf/repos.openvpn.net-as-stable.repo“
- “wget http://repos.openvpn.net/repos/yum/conf/repos.openvpn.net-CentOS6-snapshots.repo“
- openVPN has been “installed” into /usr/share/doc/openvpn-2.3.2/
- easy-rsa has been “installed” into /usr/share/easy-rsa/
- copy the easy-rsa files into /etc/openvpn/: “cp -r /usr/share/easy-rsa/* /etc/openvpn/“
- now go into that directory: “cd /etc/openvpn/“
- you can edit the vars file. it is used to set up the defaults you need to generate your keys. I changed a few things. This step is optional…but if you edit it, you can just go through some future steps hitting enter.
export KEY_SIZE=2048 (default was 1024. Bigger is better)
export KEY_COUNTRY=”XX” (your country)
export KEY_PROVINCE=”XX” (state)
export KEY_CITY=”XXXXXXXX” (city)
export KEY_ORG=”XXXXXXXXX” (organization)
export KEY_EMAIL=”XXXXXX@XXXXXXXXX.XXX” (email)
export KEY_EMAIL=XXXXXX@XXXXXXXXX.XXX (email again…no quotes) - Now run it “./vars“
- Run “./clean-all” to make sure there’s no junk around
- Run “./build-ca” to start the process of making your “master” certificate. This will take a while since you are making a 2048 bit key. Let it run. Mine took about 5 min or so to finish
- When it finishes, build the key for your server “./build-key-server server“
- Build the keys for each client you want “./build-key client1” You can replace client1 with whatever you want the client called. It just needs to be unique
- Copy the sample server config file into /etc/openvpn/. “cp /usr/share/doc/openvpn-2.3.2/sample-config-files/server.conf /etc/openvpn/server.conf” When I did this at first, I put it into a subdirectory called conf. Don’t do this. Just put your conf file into /etc/openvpn/. This becomes important when it comes time to run it as a service.
- Now, edit the file “nano server.conf“
- You’ll have to make some changes in the file. Read the comments and everything should become clear. Here’s my file:
—–
#################################################
# 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 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 tap
dev tun
tun-mtu 1500
tun-mtu-extra 32
mssfix 1450# 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 /etc/openvpn/keys/ca.crt
cert /etc/openvpn/keys/server.crt
key /etc/openvpn/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 /etc/openvpn/keys/dh2048.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
server 192.168.27.0 255.255.255.0# 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# Configure server mode for ethernet bridging
# using a DHCP-proxy, where clients talk
# to the OpenVPN server-side DHCP server
# to receive their IP address allocation
# and DNS server addresses. You must first use
# your OS’s bridging capability to bridge the TAP
# interface with the ethernet NIC interface.
# Note: this mode only works on clients (such as
# Windows), where the client-side TAP adapter is
# bound to a DHCP client.
;server-bridge# 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”# 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
# or bridge the TUN/TAP interface to the internet
# in order for this to work properly).
push “redirect-gateway def1”# Certain Windows-specific network settings
# can be pushed to clients, such as DNS
# or WINS server addresses. CAVEAT:
# http://openvpn.net/faq.html#dhcpcaveats
# The addresses below refer to the public
# DNS servers provided by opendns.com.
push “dhcp-option DNS 208.67.222.222”
push “dhcp-option DNS 208.67.220.220”# 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 3# 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
—– - you can now run the server by “openvpn server.conf“
I’ll do another post detailing firewall changes and then a third detailing client configuration.
References:
http://www.servermom.com/how-to-build-openvpn-server-on-centos-6-x/732/ — main guide I used
http://www.webhostingtalk.com/showthread.php?t=1167872 — another howto I used
http://openvpn.net/index.php/open-source/documentation/howto.html — openVPN docs I referred to
http://wiki.centos.org/HowTos/Network/IPTables — big BIG huge help with getting iptables set up right
[Update 2013-06-30 07:14:07] Edited step 34
[Update 2013-06-30 07:53:27] I’ve finished step 3b detailing firewall changes with iptables and starting the server as a daemon