OpenVPN/fingerprint-authentication

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Article status
This article has some todo items:
  • add IPv6 example(when IPv4 is ready)

OpenVPN's traditional setup works with using and managing Certificate Authorities (CA)s. Many TLS-based protocols also allow an alternative and simpler mode in which rather than verify certificates using Certificate Authorities (CA)s, the certificate itself is hashed and compared against a pre-known set of acceptable hashes. This is usually referred to as fingerprint verification. It is popular across SMTP servers, IRC servers, XMPP servers, and even in the context of HTTP with pinning.

Since OpenVPN version 2.7 the --secret support has been removed. The static key setup mode (non-TLS), is no longer a secure enough for nowadays requirements. The replacement for the removed static key setup method is now using TLS mode instead.

The --peer-fingerprint makes the TLS mode setup as easy, as it has been using the --secret static key setup using older OpenVPN versions.

This setup is not suggested to be a replacement for the main and traditional OpenVPN setup using a Certificate Authority (CA). This alternative way of configuring OpenVPN is meant for situational and ad-hoc network setup and is targeted for small VPN network setups.

Tip
This setup method does not scale well, in terms of further administration and expanding its configuration, if dealing with a large amount of VPN clients. For large VPN network setups use the traditional OpenVPN setup.

Further technical informations regarding its main focused use-case area in openvpn-networking, and the initial request for adding support for fingerprint authenticaction are found in the official mailing.

Installation

Additional software

  • dev-libs/openssl - Robust, full-featured Open Source Toolkit for the Transport Layer Security (TLS)

Configuration

The setup explained below uses suggestive configure filename /etc/openvpn/P2P.conf for the openvpn service and has the smallest configurable IP VPN client pool configured, to support and to focus on its targeted small VPN network, Peer to Peer or Point-to-Point, ad-hoc network primary usage area.

The setup example setup explained below uses a different UDP 11194port setting for the openvpn server, and the VPN client subnet is set to 192.168.254.248/29, compared to the main OpenVPN setup. Using that settings, both setups of openvpn, OpenVPN and explained below, can run on the same openvpn server simultaneously.

Environment variables

Configuration:

  • dev - tun1 or tap1 device
  • proto - Define protocol udp, tcp, udp6 or tcp6 for communicating with peer.
  • port - TCP/UDP port for for local and remote.
  • topology - Set IP topology used for tun device: subnet or p2p.

Table overview:

Hostname Interface IP address Gateway Network description
server eth0 192.168.100.1/24 Private
eth1 203.0.113.1/24 Public - internet
tun1 192.168.254.249/29 VPN
client eth0 192.0.2.11/24 192.0.2.1 Private or Public
tun1 192.168.254.250/29 VPN
dns1 eth0 192.168.100.100/24 192.168.100.1 Private

Explain shortly, using simple words about the DNS and its gateway in this scenario, and why it is working

Tip
The example DNS server is directly connected to the OpenVPN server. The OpenVPN server is the default-gateway of the DNS server. This is important for the reachability of the DNS server after the VPN connection has been established.
Note
This is a example IP scenario used in this document. For real world usage, change the according IP networking entries.

Files

Set the openvpn deamon running options to use local syslog. Add the --syslog running option to enable syslog logging:

FILE /etc/conf.d/openvpnSet logging to local syslog
[...]
# Additional arguments to pass to openvpn.
command_args="--syslog"

Apply this setting to all nodes, here in document to the server and to the client.

Server

Files

  • /etc/conf.d/openvpn - Daemon (system wide) configuration file.
  • /etc/openvpn/P2P.conf - Global (system wide) configuration file.
  • /etc/openvpn/server/server.key - OpenVPN server's private key
  • /etc/openvpn/server/server.crt - OpenVPN server's self-signed certificate.
  • /etc/openvpn/server/dh2048.pem - Diffie-Helman (DH) parameter file.

Create necessary directory structure

root #mkdir -p /etc/openvpn/server

Change to the openvpn configuration directory, before generating any files

root #cd /etc/openvpn

Generate server.key, a self-signed certificate server.crt. The certificate created in is valid the next 3650 days:

root #openssl req -x509 -newkey ec:<(openssl ecparam -name secp384r1) -keyout server.key -out server.crt -nodes -sha256 -days 3650 -subj '/CN=server'

Generate a SHA256 fingerprint of the /etc/openvpn/server.crt file:

root #openssl x509 -fingerprint -sha256 -in server.crt -noout
sha256 Fingerprint=18:6D:DD:6A:C8:45:7F:A0:9D:89:B0:30:D4:67:02:18:2D:F4:A8:83:F8:EA:D7:14:6D:0E:0B:47:BF:31:71:CF

This generated fingerprint will be put into openvpn clients configuration: 

18:6D:DD:6A:C8:45:7F:A0:9D:89:B0:30:D4:67:02:18:2D:F4:A8:83:F8:EA:D7:14:6D:0E:0B:47:BF:31:71:CF

Generate the DH parameter file using openssl. Generate directly to /etc/openvpn/server/ server directory:

root #openssl dhparam -out server/dh2048.pem 2048

Finally move the generated server.key and the server.crt files to the /etc/openvpn/server directory:

root #mv *.key *.crt /etc/openvpn/server

Create a server configuration file named /etc/openvpn/P2P.conf:

FILE /etc/openvpn/P2P.confServer example setup with peer-fingerprint authentication
# openvpn 2.6.x version 
# set interface
dev tun1

# set protocol
proto udp

# set port
port 11194

# certificates and keys paths
cert server/server1.crt
key server/server1.key
dh server/dh2048.pem

# set the cipher to be used
cipher AES-256-GCM:AES-128-GCM:CHACHA20-POLY1305

# set the topology
topology subnet

# vpn client IP subnet assing pool
server 192.168.254.248 255.255.255.248

# persistent device and key settings
persist-key
persist-tun

# update vpn clients IP routing table
push "route 192.168.100.0 255.255.255.0"

# update vpn clients DNS entry
push "dhcp-option DNS 192.168.100.100"

# connection
keepalive 60 300

# notify clients on deamon restart to reconnect quickly
explicit-exit-notify 1

# run the server as system user/group nobody
user nobody
group nobody
                            
# fingerprints of trusted VPN clients. Restart is mandatory after modifying client entries.
<peer-fingerprint>
07:A8:30:0D:F5:8A:9A:F3:70:1C:7C:FD:FC:BD:36:97:45:FE:19:2A:C9:1F:72:B1:C0:A4:EE:81:27:22:BD:A6
</peer-fingerprint>

Add a openvpn service to openrc

root #ln -s /etc/init.d/openvpn /etc/init.d/openvpn.P2P

Before starting the configured openvpn daemon on the server, display the current state of:

  • Active system interfaces
  • IP routing table

Use the ip link show up command to list the currently active system interfaces. The command line output shows 2 active interfaces:

  • eth0
  • eth1

when leaving out the lo - loopback interface.

user $ip link show up
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP mode DEFAULT group default qlen 1000
    link/ether 0c:64:f8:f1:00:00 brd ff:ff:ff:ff:ff:ff
3: eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP mode DEFAULT group default qlen 1000
    link/ether 0c:64:f8:f1:00:01 brd ff:ff:ff:ff:ff:ff

Use the ip route command to display the IP routing table. The routing table displays 2 entries:

  • private IP network 192.168.100.0/24 conntected to the eth0 interface
  • public IP network 203.0.113.0/24 conntected to the eth1 interface
user $ip route
default via 203.0.113.1 dev eth0 metric 202 
192.168.100.0/24 dev eth1 proto kernel scope link src 192.168.100.1 
203.0.113.0/24 dev eth0 proto kernel scope link src 203.0.113.2

The openvpn server is the IP gateway for both connected networks at eth0 and the eth1 interfaces.

Start the daemon and add to the default startup:

root #rc-service openvpn.P2P start
root #rc-update add openvpn.P2P default

After the openvpn daemon has been started following system entries have changed.

Use the ip link show up command to list the currently active system interfaces. This output displays now 3 active interfaces on the server. Notice the new tun1 inteface:

user $ip link show up
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP mode DEFAULT group default qlen 1000
    link/ether 0c:64:f8:f1:00:00 brd ff:ff:ff:ff:ff:ff
3: eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP mode DEFAULT group default qlen 1000
    link/ether 0c:64:f8:f1:00:01 brd ff:ff:ff:ff:ff:ff
8: tun1: <POINTOPOINT,MULTICAST,NOARP,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UNKNOWN mode DEFAULT group default qlen 500
    link/none

Use the ip route command to display the servers IP routing table. This shows the server is now connected to a additional IP network 192.168.254.249/29 using the IP address 192.168.254.249 on the tun1 interface, this is the VPN client network:

user $ip route
default via 203.0.113.1 dev eth0 metric 202 
192.168.100.0/24 dev eth1 proto kernel scope link src 192.168.100.1
192.168.254.248/29 dev tun1 proto kernel scope link src 192.168.254.249
203.0.113.0/24 dev eth0 proto kernel scope link src 203.0.113.2

Verify the new tun1 interface by simply using the ping command to its configured IP address:

user $ping 192.168.254.249
64 bytes from 192.168.254.249: seq=0 ttl=42 time=0.067 ms
[...]
--- 192.168.254.249 ping statistics ---
1 packets transmitted, 5 packets received, 0% packet loss
round-trip min/avg/max = 0.067/0.067/0.067 ms

The interface should respond with usual ICMP echo reply message to the send ping command.

Client

The client configuration process shown below compared to the official setup has one difference. The original client setup generates the fingerprint for the openvpn server using a already finished /etc/openvpn/P2P.conf configuration file. Citation from the original setup document:

Generate the fingerprint of the client certificate. For that we will let OpenSSL read the client configuration file as the x509 command will ignore anything that is not between the begin and end markers of the certificate.

The resulting command would be here:

user $openssl x509 -fingerprint -sha256 -noout -in /etc/openvpn/P2P.conf

The begin and the end markers in the client configuration file: 

<cert>
-----BEGIN CERTIFICATE-----
[...]
-----END CERTIFICATE-----
</cert>
Important
The result of both commands, the <fingerprint> must be the identical. No matter which file is used for generation.

Files

  • /etc/conf.d/openvpn - Daemon (system wide) configuration file.
  • /etc/openvpn/P2P.conf - Global (system wide) configuration file.
  • /etc/openvpn/client/client.key - OpenVPN client's private key.
  • /etc/openvpn/client/client.crt - OpenVPN client's self-signed certificate.

Create necessary directory structure

root #mkdir -p /etc/openvpn/client

Change to the openvpn configuration directory, before generating any files

root #cd /etc/openvpn

Generate a self-signed certificate for the client

root #openssl req -x509 -newkey ec:<(openssl ecparam -name secp384r1) -keyout client.key -out client.crt -nodes -sha256 -days 3650 -subj '/CN=client'

Generate SHA256 fingerprint of the client.crt file

root #openssl x509 -fingerprint -sha256 -noout -in client.crt
sha256 Fingerprint=07:A8:30:0D:F5:8A:9A:F3:70:1C:7C:FD:FC:BD:36:97:45:FE:19:2A:C9:1F:72:B1:C0:A4:EE:81:27:22:BD:A6

This generated fingerprint will be put into openvpn servers configuration, into the <peer-fingerprint> section, at last entry: 

07:A8:30:0D:F5:8A:9A:F3:70:1C:7C:FD:FC:BD:36:97:45:FE:19:2A:C9:1F:72:B1:C0:A4:EE:81:27:22:BD:A6

Include the files client.key and client.crt, generated at the beginning in the configuration file.

  • Put the content of the client.key file to the <key></key> section
  • Put the content of the client.crt file to the <cert></cert> section

Finally move the generated client.key and the client.crt files to the /etc/openvpn/client/ directory:

root #mv *.key *.crt /etc/openvpn/client

Both files are now included in the configuriaton file and are not needed anymore.

Create a client configuration file named /etc/openvpn/P2P.conf:

FILE /etc/openvpn/P2P.confClients peer-fingerprint authentication
# openvpn 2.6.x version 
# set interface
dev tun1

# set protocol
proto udp

# set the target IP and port of trusted server
remote 203.0.113.2 11194

# client
client

# add the content of the clients .key and .crt file here:
<key>
-----BEGIN PRIVATE KEY-----
MIG2AgEAMBAGByqGSM49AgEGBSuBBAAiBIGeMIGbAgEBBDBuGSpQzWMSK/vxrmxz
pSrxNfoIKJhlzgB5+Or9e0S8ApTwRfbBSqUQd7kDtlfwJNihZANiAARbNnf1L0di
zO+cgQ517CYk6TBMHHAAB5dDNjhk28xipw8Af47oGQny7KR8wpyyAIuqBXv3+A27
ECwDkaB+qIBziQqyBnuh+MoMp01yOYXBveC0fFdkMslPwyzmNcKjeuA=
-----END PRIVATE KEY-----
</key>
<cert>
-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----
</cert>

# set the trusted openvpn server "peer-fingerprint" here:
peer-fingerprint 18:6D:DD:6A:C8:45:7F:A0:9D:89:B0:30:D4:67:02:18:2D:F4:A8:83:F8:EA:D7:14:6D:0E:0B:47:BF:31:71:Cf

Add a openvpn service to openrc

root #ln -s /etc/init.d/openvpn /etc/init.d/openvpn.P2P

Usage

Before starting the configured openvpn on the client, display the current state of:

  • Active system interfaces
  • IP routing table
  • DNS setting, only the VPN client

Client

Use the ip link show up command to list the currently active system interfaces. The command line output shows 2 active interfaces:

  • lo
  • eth1
user $ip link show up
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP mode DEFAULT group default qlen 1000
    link/ether 0c:a2:44:59:00:00 brd ff:ff:ff:ff:ff:ff

Use the ip route command to display the IP routing table on the client:

  • IP network 192.0.2.0/24connected to the eth0 interface
user $ip route
default via 192.0.2.1 dev eth0 metric 202 
192.0.2.0/24 dev eth0 proto kernel scope link src 192.0.2.10
Note
It is not important for the setup here, on the client, to distinguish between private and public IP networks. The setup will work in both networks the same way.

Display the current setting for DNS on the opevpn client the system:

user $more /etc/resolv.conf
nameserver 192.0.2.1

The output shows the openvpn clients DNS server is set to a IP in the local area network 192.0.2.1. In most cases the local router IP address, the default gateway IP address is also the DNS server.

OpenRC

Now start the openvpn.P2P application:

root #service openvpn.P2P start

systemd

root #systemctl start openvpn-client

The routine explained below is a set of commands to verify the proper working for this setup.

Client

link

Use the ip link show up command to list the currently active system interfaces. The output shows the tun1 interface has shown up among the active interfaces:

user $ip link show up
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP mode DEFAULT group default qlen 1000
    link/ether 0c:a2:44:59:00:00 brd ff:ff:ff:ff:ff:ff
4: tun1: <POINTOPOINT,MULTICAST,NOARP,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UNKNOWN mode DEFAULT group default qlen 500
    link/none

IP routing

The clients routing table shows 2 new entries:

  • VPN client IP network 192.168.254.248/29 available on the tun1 interface
  • VPN client IP network 192.168.100.0/24 available via the tun1 interface
user $ip route
default via 192.0.2.1 dev eth0 metric 202 
192.0.2.0/24 dev eth0 proto kernel scope link src 192.0.2.10 
192.168.100.0/24 via 192.168.254.249 dev tun1 
192.168.254.248/29 dev tun1 proto kernel scope link src 192.168.254.250

DNS

Display the current setting for DNS on the opevpn client the system:

user $more /etc/resolv.conf
# Generated by openvpn for interface tun1
domain example.net
nameserver 192.168.100.100

The output shows the openvpn clients DNS server entry has changed to the DNS server configured for the VPN network in the server configuration part. It is set to a IP address used in the VPN private IP network, (check the IP table overview) it is the 192.168.100.100.

The IP address set by the openvpn software, should be reachable and respond to send ping commands. Verify its reachability using ping:

user $ping 192.168.100.100
PING 192.168.100.100 (192.168.100.100): 56 data bytes
[...]
64 bytes from 192.168.100.100: seq=4 ttl=42 time=2.688 ms

--- 192.168.100.100 ping statistics ---
5 packets transmitted, 5 packets received, 0% packet loss
round-trip min/avg/max = 2.688/3.231/3.664 ms

Now as last check, try out if the name resolution works. Here pinging the dns1 server:

user $ping dns1
PING dns1 (192.168.100.100): 56 data bytes
[...]
64 bytes from 192.168.100.100: seq=4 ttl=42 time=3.146 ms

--- dns1 ping statistics ---
5 packets transmitted, 5 packets received, 0% packet loss
round-trip min/avg/max = 3.146/3.280/3.468 ms

The setup of a secure connection is now completed. Everything should work as expected at this point. If still running into issues read the troubleshooting section below.

Server

To find out which IP address, from the configured IP pool, 192.168.254.248/29 has been assigned to the connected client VPN client, use the OpenVPN management interface or use the command:

root #grep 192.168.254 /var/log/messages
...
Feb 12 19:01:42 server daemon.notice P2P[2139]: client/192.0.2.10:43026 MULTI_sva: pool returned IPv4=192.168.254.250, IPv6=(Not enabled)

Verify the client connectivity by using the ping command. Ping the clients tun1IP address, after the connection from the client has been established.

user $ping 192.168.254.250
PING 192.168.254.250 (192.168.254.250): 56 data bytes
[...]
--- 192.168.254.250 ping statistics ---
5 packets transmitted, 5 packets received, 0% packet loss
round-trip min/avg/max = 2.008/2.252/2.525 ms

The remote target IP of the client, connected to the tun1 interface, should respond with ICMP echo reply message to the send ping command.

Gentoo specifics

The init script allows multiple tunnels. Decide on a name for the tunnel - eg EXAMPLE.

OpenRC

root #ln -s /etc/init.d/openvpn /etc/init.d/openvpn.EXAMPLE

Now create config as /etc/openvpn/EXAMPLE.conf:

root #service openvpn.EXAMPLE start

systemd

Due to dependencies server and client operations are separated into two units.

Create the server config as /etc/openvpn/server/EXAMPLE.conf:

root #systemctl start openvpn-server@EXAMPLE

Create the client config as /etc/openvpn/client/EXAMPLE.conf:

root #systemctl start openvpn-client@EXAMPLE

More tunnels can be created by replacing EXAMPLE with more names. Each one has its own configuration and can be stopped and started individually. The default is simply to use openvpn.conf and not symlink the service. Both methods may of course be used.

Troubleshooting

Management Interface

Add following lines to the /etc/openvpn/P2P.conf. Choose any desirable, free TCP port available at localhost. In example 7206:

FILE /etc/openvpn/openvpn.confAdd right at the top, 1-st configuration entry
management localhost 7206
...

Restart the daemon:

root #service openvpn restart

Connect to the openvpn management interface. The management session output shown on the openvpn server side.

Example of a successfull authentication procedure done with openvpn using configuration shown:

user $telnet localhost 7206
Trying ::1...
Connected to localhost.
Escape character is '^]'.
>INFO:OpenVPN Management Interface Version 5 -- type 'help' for more info
>CLIENT:ESTABLISHED,0
>CLIENT:ENV,n_clients=1
>CLIENT:ENV,time_unix=1707763011
>CLIENT:ENV,time_ascii=2024-02-12 19:36:51
>CLIENT:ENV,ifconfig_pool_netmask=255.255.255.248
>CLIENT:ENV,ifconfig_pool_remote_ip=192.168.254.250
>CLIENT:ENV,trusted_port=60503
>CLIENT:ENV,trusted_ip=192.0.2.10
>CLIENT:ENV,common_name=client1
>CLIENT:ENV,IV_COMP_STUBv2=1
>CLIENT:ENV,IV_COMP_STUB=1
>CLIENT:ENV,IV_LZO_STUB=1
>CLIENT:ENV,IV_PROTO=990
>CLIENT:ENV,IV_CIPHERS=AES-256-GCM:AES-128-GCM:CHACHA20-POLY1305
>CLIENT:ENV,IV_NCP=2
>CLIENT:ENV,IV_MTU=1600
>CLIENT:ENV,IV_TCPNL=1
>CLIENT:ENV,IV_PLAT=linux
>CLIENT:ENV,IV_VER=2.6.8
>CLIENT:ENV,untrusted_port=60503
>CLIENT:ENV,untrusted_ip=192.0.2.10
>CLIENT:ENV,tls_serial_hex_0=41:b7:09:12:be:0a:0d:df:7e:d3:f1:ef:82:ad:6f:61:7f:c3:be:e1
>CLIENT:ENV,tls_serial_0=375166226863142187075343339831211958748733226721
>CLIENT:ENV,tls_digest_sha256_0=07:a8:30:0d:f5:8a:9a:f3:70:1c:7c:fd:fc:bd:36:97:45:fe:19:2a:c9:1f:72:b1:c0:a4:ee:81:27:22:bd:a6
>CLIENT:ENV,tls_digest_0=96:f4:1b:ae:75:08:27:d9:4d:d2:cf:ee:e4:66:f8:7c:a1:de:2b:ff
>CLIENT:ENV,tls_id_0=CN=client1
>CLIENT:ENV,X509_0_CN_1=client1
>CLIENT:ENV,X509_0_CN=client1
>CLIENT:ENV,remote_port_1=11194
>CLIENT:ENV,local_port_1=11194
>CLIENT:ENV,proto_1=udp
>CLIENT:ENV,daemon_pid=2345
>CLIENT:ENV,daemon_start_time=1707763000
>CLIENT:ENV,daemon_log_redirect=0
>CLIENT:ENV,daemon=1
>CLIENT:ENV,verb=1
>CLIENT:ENV,config=/etc/openvpn/P2P.conf
>CLIENT:ENV,PEER_DNS=yes
>CLIENT:ENV,RC_SVCNAME=openvpn.P2P
>CLIENT:ENV,ifconfig_local=192.168.254.249
>CLIENT:ENV,ifconfig_netmask=255.255.255.248
>CLIENT:ENV,script_context=init
>CLIENT:ENV,tun_mtu=1500
>CLIENT:ENV,dev=tun1
>CLIENT:ENV,dev_type=tun
>CLIENT:ENV,redirect_gateway=0
>CLIENT:ENV,END

Leave the OpenVPN management interface by using the quit command:

user $exit

For further information read OpenVPN management interface usage manual.

External resouces

Retrieved from "https://wiki.gentoo.org/index.php?title=OpenVPN/fingerprint-authentication&oldid=1280754"