OpenVPN

Revision as of 01:03, 6 November 2011

OpenVPN
What:
VPN server
Participants:
Jaroslov, Abe
Locations:
Whitespace
Tweet

Client

Create a new key

Linux/windows:

   $ openssl genrsa -aes256 -out 0x20-vpn-your_name_here.key 2048

Create a Certificate signing request

   $ openssl req -new -key 0x20-vpn-your_name_here.key -out 0x20-vpn-your_name_here.csr
           countryName               = BE
           stateOrProvinceName       = Ghent
           organizationName          = 0x20
           organizationalUnitName    = members
           commonName                = your_name_here

Get your certificate signed

Mail your CSR(certificate signing request) to someone who has access to the 0x20 CA. Best is being physically present in the space.

Sign cert:

   $ openssl ca -in ../0x20-vpn-your_name_here.csr -cert ca-0x20-cert.pem -keyfile private/ca-0x20-key.pem -out 0x20-vpn-your_name_here.cert -config ./openssl.cnf

Client config Linux

• apt-get install openvpn
• create following config file: /etc/openvpn/0x20-vpn.conf and change values in bold

   client
   remote members.0x20.be 1194
   proto udp 
   dev tun  
   
   resolv-retry infinite
   nobind
   
   user nobody
   group nogroup
       
   persist-key
   persist-tun
   
   ca certs/ca-0x20-cert.pem
   cert certs/0x20-vpn-<name>.cert
   key certs/0x20-vpn-<name>.key
   
   ns-cert-type server
   
   # If a tls-auth key is used on the server
   # then every client must also have the key.
   ;tls-auth ta.key 1
  
   cipher AES-256-CBC
   comp-lzo
   
   verb 3
   mute 20

Client config Wintendo

• Get openvpn for windows here version OpenVPN 2.2.1 or higher
• Save this content to this filename C:\Program Files\OpenVPN\config\Openvpn_0x20.ovpn

client
remote members.0x20.be 1194
proto udp 
dev tun  

resolv-retry infinite
nobind

user nobody
group nogroup
 
persist-key
persist-tun

#change the paths as needed.
ca "C:\\Program Files\\OpenVPN\\easy-rsa\\keys\\ca-0x20-cert.pem"
cert "C:\\Program Files\\OpenVPN\\easy-rsa\\keys\\0x20-vpn-your_name_here.cert"
key "C:\\Program Files\\OpenVPN\\easy-rsa\\keys\\0x20-vpn-your_name_here.key"


ns-cert-type server

# If a tls-auth key is used on the server
# then every client must also have the key.
;tls-auth ta.key 1
  
cipher AES-256-CBC
comp-lzo

verb 3
mute 20

• open cmd with administrator privileges (start menu -> cmd -> run as admin)
• cd Program Files\OpenVPN\easy-rsa
• give command init-config.bat
• Save following content as C:\Progra~1\OpenVPN\easy-rsa\openssl.cnf

#
# OpenSSL example configuration file.
# This is mostly being used for generation of certificate requests.
#

# This definition stops the following lines choking if HOME isn't
# defined.
HOME			= .
RANDFILE		= $ENV::HOME/.rnd

# Extra OBJECT IDENTIFIER info:
#oid_file		= $ENV::HOME/.oid
oid_section		= new_oids

# To use this configuration file with the "-extfile" option of the
# "openssl x509" utility, name here the section containing the
# X.509v3 extensions to use:
# extensions		= 
# (Alternatively, use a configuration file that has only
# X.509v3 extensions in its main [= default] section.)

[ new_oids ]

# We can add new OIDs in here for use by 'ca' and 'req'.
# Add a simple OID like this:
# testoid1=1.2.3.4
# Or use config file substitution like this:
# testoid2=${testoid1}.5.6

####################################################################
[ ca ]
default_ca	= CA_default		# The default ca section

####################################################################
[ CA_default ]

dir		= C:/user/local/ssl		# Where everything is kept
certs		= $dir			# Where the issued certs are kept
crl_dir		= $dir			# Where the issued crl are kept
database	= $dir/index.txt	# database index file.
new_certs_dir	= $dir			# default place for new certs.

certificate	= $dir/ca.crt	 	# The CA certificate
serial		= $dir/serial 		# The current serial number
crl		= $dir/crl.pem 		# The current CRL
private_key	= $dir/ca.key	 	# The private key
RANDFILE	= $dir/.rand		# private random number file

x509_extensions	= usr_cert		# The extentions to add to the cert

# Extensions to add to a CRL. Note: Netscape communicator chokes on V2 CRLs
# so this is commented out by default to leave a V1 CRL.
# crl_extensions	= crl_ext

default_days	= 3650			# how long to certify for
default_crl_days= 30			# how long before next CRL
default_md	= md5			# which md to use.
preserve	= no			# keep passed DN ordering

# A few difference way of specifying how similar the request should look
# For type CA, the listed attributes must be the same, and the optional
# and supplied fields are just that :-)
policy		= policy_match

# For the CA policy
[ policy_match ]
countryName		= match
stateOrProvinceName	= match
organizationName	= match
organizationalUnitName	= optional
commonName		= supplied
emailAddress		= optional

# For the 'anything' policy
# At this point in time, you must list all acceptable 'object'
# types.
[ policy_anything ]
countryName		= optional
stateOrProvinceName	= optional
localityName		= optional
organizationName	= optional
organizationalUnitName	= optional
commonName		= supplied
emailAddress		= optional

####################################################################
[ req ]
default_bits		= 2048
default_keyfile 	= privkey.pem
distinguished_name	= req_distinguished_name
attributes		= req_attributes
x509_extensions	= v3_ca	# The extentions to add to the self signed cert

# Passwords for private keys if not present they will be prompted for
# input_password = secret
# output_password = secret

# This sets a mask for permitted string types. There are several options. 
# default: PrintableString, T61String, BMPString.
# pkix	 : PrintableString, BMPString.
# utf8only: only UTF8Strings.
# nombstr : PrintableString, T61String (no BMPStrings or UTF8Strings).
# MASK:XXXX a literal mask value.
# WARNING: current versions of Netscape crash on BMPStrings or UTF8Strings
# so use this option with caution!
string_mask = nombstr

# req_extensions = v3_req # The extensions to add to a certificate request

[ req_distinguished_name ]
countryName			= Country Name (2 letter code)
countryName_default		= BE
countryName_min			= 2
countryName_max			= 2

stateOrProvinceName		= State or Province Name (full name)
stateOrProvinceName_default	= Ghent

localityName			= Locality Name (eg, city)
localityName_default		= Whitespace

0.organizationName		= Organization Name (eg, company)
0.organizationName_default	= 0x20

# we can do this but it is not needed normally :-)
#1.organizationName		= Second Organization Name (eg, company)
#1.organizationName_default	= World Wide Web Pty Ltd

organizationalUnitName		= Organizational Unit Name (eg, section)
organizationalUnitName_default	= members

commonName			= Common Name (eg, your name or your server\'s hostname)
commonName_max			= 64

emailAddress			= Email Address
#emailAddress_default		= $ENV::KEY_EMAIL
emailAddress_max		= 40

# SET-ex3			= SET extension number 3

[ req_attributes ]
challengePassword		= A challenge password
challengePassword_min		= 4
challengePassword_max		= 20

unstructuredName		= An optional company name

[ usr_cert ]

# These extensions are added when 'ca' signs a request.

# This goes against PKIX guidelines but some CAs do it and some software
# requires this to avoid interpreting an end user certificate as a CA.

basicConstraints=CA:FALSE

# Here are some examples of the usage of nsCertType. If it is omitted
# the certificate can be used for anything *except* object signing.

# This is OK for an SSL server.
# nsCertType			= server

# For an object signing certificate this would be used.
# nsCertType = objsign

# For normal client use this is typical
# nsCertType = client, email

# and for everything including object signing:
# nsCertType = client, email, objsign

# This is typical in keyUsage for a client certificate.
# keyUsage = nonRepudiation, digitalSignature, keyEncipherment

# This will be displayed in Netscape's comment listbox.
nsComment			= "OpenSSL Generated Certificate"

# PKIX recommendations harmless if included in all certificates.
subjectKeyIdentifier=hash
authorityKeyIdentifier=keyid,issuer:always

# This stuff is for subjectAltName and issuerAltname.
# Import the email address.
# subjectAltName=email:copy

# Copy subject details
# issuerAltName=issuer:copy

#nsCaRevocationUrl		= http://www.domain.dom/ca-crl.pem
#nsBaseUrl
#nsRevocationUrl
#nsRenewalUrl
#nsCaPolicyUrl
#nsSslServerName

[ server ]

# JY ADDED -- Make a cert with nsCertType set to "server"
basicConstraints=CA:FALSE
nsCertType			= server
nsComment			= "OpenSSL Generated Server Certificate"
subjectKeyIdentifier=hash
authorityKeyIdentifier=keyid,issuer:always

[ v3_req ]

# Extensions to add to a certificate request

basicConstraints = CA:FALSE
keyUsage = nonRepudiation, digitalSignature, keyEncipherment

[ v3_ca ]


# Extensions for a typical CA


# PKIX recommendation.

subjectKeyIdentifier=hash

authorityKeyIdentifier=keyid:always,issuer:always

# This is what PKIX recommends but some broken software chokes on critical
# extensions.
#basicConstraints = critical,CA:true
# So we do this instead.
basicConstraints = CA:true

# Key usage: this is typical for a CA certificate. However since it will
# prevent it being used as an test self-signed certificate it is best
# left out by default.
# keyUsage = cRLSign, keyCertSign

# Some might want this also
# nsCertType = sslCA, emailCA

# Include email address in subject alt name: another PKIX recommendation
# subjectAltName=email:copy
# Copy issuer details
# issuerAltName=issuer:copy

# DER hex encoding of an extension: beware experts only!
# obj=DER:02:03
# Where 'obj' is a standard or added object
# You can even override a supported extension:
# basicConstraints= critical, DER:30:03:01:01:FF

[ crl_ext ]

# CRL extensions.
# Only issuerAltName and authorityKeyIdentifier make any sense in a CRL.

# issuerAltName=issuer:copy
authorityKeyIdentifier=keyid:always,issuer:always

Important: When executing openvpn use administrator permissions (run as administrator).

Server members.0x20.be

• server mode
• uses 0x20 CA
• only accepts client certificates with OU=members
• uses crl
• range 172.20.200.0/24

OpenVPN config

• /etc/openvpn/public.conf :

mode server
lport 1194
proto udp 
dev-type tun 
dev vpn-public

ca certs/ca-0x20-cert.pem
crl-verify certs/ca-0x20-crl.pem
cert certs/0x20-members-vpn.cert
key certs/0x20-members-vpn.key # This file should be kept secret
dh certs/dh2048.pem

tls-verify "./certs/verify-ou members"

server 172.20.200.0 255.255.255.0
ifconfig-pool-persist ipp.txt
push "route 172.22.32.0 255.255.255.0"
push "redirect-gateway def1"

comp-lzo
cipher AES-256-CBC

user nobody
group nogroup

status /var/log/openvpn-status-public.log
log-append /var/log/openvpn-public.log
verb 2
mute 20

• /etc/openvpn/certs/verify-ou :

#!/usr/bin/perl

# verify-cn -- a sample OpenVPN tls-verify script
#
# Return 0 if cn matches the common name component of
# X509_NAME_oneline, 1 otherwise.
#
# For example in OpenVPN, you could use the directive:
#
#   tls-verify "./verify-cn Test-Client"
#
# This would cause the connection to be dropped unless
# the client common name is "Test-Client"

die "usage: verify-cn cn certificate_depth X509_NAME_oneline" if (@ARGV != 3); 

# Parse out arguments:
#   ou    -- The common name which the client is required to have,
#            taken from the argument to the tls-verify directive
#            in the OpenVPN config file.
#   depth -- The current certificate chain depth.  In a typical
#            bi-level chain, the root certificate will be at level
#            1 and the client certificate will be at level 0.
#            This script will be called separately for each level.
#   x509  -- the X509 subject string as extracted by OpenVPN from
#            the client's provided certificate.
($ou, $depth, $x509) = @ARGV;

if ($depth == 0) {
    # If depth is zero, we know that this is the final
    # certificate in the chain (i.e. the client certificate),
    # and the one we are interested in examining.
    # If so, parse out the common name substring in
    # the X509 subject string.

    if ($x509 =~ /\/OU=([^\/]+)/) {
    # Accept the connection if the X509 common name
    # string matches the passed cn argument.
    if ($ou eq $1) {
        exit 0;
    }   
    }   

    # Authentication failed -- Either we could not parse
    # the X509 subject string, or the common name in the
    # subject string didn't match the passed cn argument.
    exit 1;
}
# If depth is nonzero, tell OpenVPN to continue processing
# the certificate chain.
exit 0;

Network config

• Enable IP forwarding:

# sysctl -w net.ipv4.ip_forward=1

• NAT:

# iptables -t nat -A POSTROUTING -s 172.20.200.0/24 -o eth0 -j MASQUERADE

• Add route to make 0x20 network (172.22.32.0/24) available over the vpn tunnel:

# route add -net 172.22.32.0 netmask 255.255.255.0 dev vpn-0x20

Setup routing on 0x20-router (soekris):

# route add -net 172.20.200.0 netmask 255.255.255.0 dev vpn-members

Server 0x20 <-> IBBT

A P2P tunnel between 0x20 and IBBT.

• 0x20/soekris config, /etc/openvpn/members.conf :

mode p2p                                       # Peer-to-peer-Mode
remote members.0x20.be                         # Peer-Address, (Dyn)DNS if it's
lport 40002                                    # local port
rport 443                                      # remote port
proto tcp-client                               # ...via TCP, use server mode
dev-type tun
dev vpn-members                                # interfacename, just individual
#tun-ipv6                                      # we want to use ipv6
comp-lzo                                       # compression
#cd /usr/local/etc/openvpn                     # here lays the key
secret members.key                             # the filename of the key
user nobody                                    # username under which openvpn
group nogroup                                  # ...group
persist-key                                    # on interruption, please keep
persist-tun                                    # on interruption, please keep
status /var/log/openvpn-status-members.log
log-append /var/log/openvpn-members.log
verb 2                                        # Verbose!
ifconfig 172.22.32.5 172.20.201.1             # addressing: 'ifconfig localip remoteip'

• members.0x20.be config, /etc/openvpn/0x20.conf :

mode p2p                                       # Peer-to-peer-Mode
remote 83.101.72.80                            # Peer-Address, (Dyn)DNS if it's
lport 443                                      # local port
rport 40002                                    # remote por 
proto tcp-server                               # ...via TCP, use server mode
dev-type tun 
dev vpn-0x20                                   # interfacename, just individual
#tun-ipv6                                      # we want to use ipv6
comp-lzo                                       # compression
#cd /usr/local/etc/openvpn                     # here lays the key 
secret 0x20.key                                # the filename of the key
user nobody                                    # username under which openvpn
group nogroup                                  # ...group
persist-key                                    # on interruption, please keep
persist-tun                                    # on interruption, please keep
status /var/log/openvpn-status-0x20.log
log-append /var/log/openvpn-0x20.log
verb 2                                         # Verbose!
ifconfig 172.20.201.1 172.22.32.5              # addressing: 'ifconfig localip remoteip'

Server

The virtual network exist out of two parts: 1) a point-to-point vpn that connects the big pipe server at the ibbt with the the whitespace network 2) a server-client vpn that allows users to