PKCS12 and certificate chain

doclm · Post by **doclm** » Wed Sep 23, 2015 12:17 pm

Hello,
I have this certificate chain for my vpn server 2.3.8, i want to use pkcs12 allows clients to connect but i encountered some issue.

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root-CA (ca.crt)
    + VPN-CA (vpn.crt)
        + server certificate (server.crt)
        + CLIENTS-CA (clients.crt)
            + Client 1 certificate (client1.crt)
            + Client 2 certificate (client2.crt)
            ...
            + Client N certificate (clientN.crt)

I created a chained ca with the following command:

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 cat vpn.crt ca.crt > chained-ca.crt

and chained clients certificate with this command:

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cat clientN.crt clients.crt > chained-clientN.crt

like what i saw here: https://community.openvpn.net/openvpn/w ... ate_Chains
Without pkcs12 i used this client configuration and everything works fine

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##############################################
# Sample client-side OpenVPN 2.0 config file #
# for connecting to multi-client server.     #
#                                            #
# This configuration can be used by multiple #
# clients, however each client should have   #
# its own cert and key files.                #
#                                            #
# On Windows, you might want to rename this  #
# file so it has a .ovpn extension           #
##############################################

# Specify that we are a client and that we
# will be pulling certain config file directives
# from the server.
client

# Use the same setting as you are using on
# the server.
# 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,
# you may need to disable the firewall
# for the TAP adapter.
;dev-node MyTap

# Are we connecting to a TCP or
# UDP server?  Use the same setting as
# on the server.
;proto tcp
proto udp

# The hostname/IP and port of the server.
# You can have multiple remote entries
# to load balance between the servers.
remote <SERVER ADDRESS> 1194
;remote my-server-2 1194

# Choose a random host from the remote
# list for load-balancing.  Otherwise
# try hosts in the order specified.
;remote-random

# Keep trying indefinitely to resolve the
# host name of the OpenVPN server.  Very useful
# on machines which are not permanently connected
# to the internet such as laptops.
resolv-retry infinite

# Most clients don't need to bind to
# a specific local port number.
nobind

# Downgrade privileges after initialization (non-Windows only)
#user nobody
#group nobody

# Try to preserve some state across restarts.
persist-key
persist-tun

# If you are connecting through an
# HTTP proxy to reach the actual OpenVPN
# server, put the proxy server/IP and
# port number here.  See the man page
# if your proxy server requires
# authentication.
;http-proxy-retry # retry on connection failures
;http-proxy [proxy server] [proxy port #]

# Wireless networks often produce a lot
# of duplicate packets.  Set this flag
# to silence duplicate packet warnings.
;mute-replay-warnings

# SSL/TLS parms.
# See the server config file for more
# description.  It's best to use
# a separate .crt/.key file pair
# for each client.  A single ca
# file can be used for all clients.
ca chained-ca.crt
cert chained-clientN.crt
key clientN.key

# Verify server certificate by checking
# that the certicate has the nsCertType
# field set to "server".  This is an
# important precaution to protect against
# a potential attack discussed here:
#  http://openvpn.net/howto.html#mitm
#
# To use this feature, you will need to generate
# your server certificates with the nsCertType
# field set to "server".  The build-key-server
# script in the easy-rsa folder will do this.
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

# Select a cryptographic cipher.
# If the cipher option is used on the server
# then you must also specify it here.
;cipher x

# Enable compression on the VPN link.
# Don't enable this unless it is also
# enabled in the server config file.
comp-lzo

# Set log file verbosity.
verb 3

# Silence repeating messages
;mute 20

then i created a .p12 file with openssl with the following command:

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openssl pkcs12 -export -inkey clientN.key -in chained-clientN.crt -certfile chained-ca.crt -out clientN.p12

and changed this line in my config

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ca chained-ca.crt
cert chained-clientN.crt
key clientN.key

to

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pkcs12 clientN.p12

and now i cannot connect anymore to the server.
From server log i saw there are some error with vpn.crt:

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Wed Sep 23 14:11:19 2015 us=760574 10.0.0.6:58947 VERIFY ERROR: depth=2, error=path length constraint exceeded: C=IT, ST=Lombardia, O=Pippo Network, OU=HQ, CN=VPN Intermediate CA, emailAddress=example@example.com
Wed Sep 23 14:11:19 2015 us=762120 10.0.0.6:58947 TLS_ERROR: BIO read tls_read_plaintext error: error:140890B2:SSL routines:SSL3_GET_CLIENT_CERTIFICATE:no certificate returned
Wed Sep 23 14:11:19 2015 us=762928 10.0.0.6:58947 TLS Error: TLS object -> incoming plaintext read error
Wed Sep 23 14:11:19 2015 us=763668 10.0.0.6:58947 TLS Error: TLS handshake failed
Wed Sep 23 14:11:19 2015 us=764867 10.0.0.6:58947 SIGUSR1[soft,tls-error] received, client-instance restarting

How can i fix it?