OpenVPN seems to push wrong subnet mask to clients

Holmes.Sherlock

I've configured an OpenVPN server with the following configuration:

#################################################
# 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 1197

# 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

# 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 keys/ca.crt
cert keys/TeamReboot.crt
key keys/TeamReboot.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 keys/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 192.168.50.0 255.255.255.0
server 10.172.0.0 255.255.255.0

# 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 logs/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 192.168.10.0 255.255.255.0"
;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
# 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 keys/ta.key 1 # 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 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 logs/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         logs/openvpn.log
log-append  logs/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

I'm connecting to the server with the following client configuration:

##############################################
# 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 <My OpenVPN Server IP> 1197

# 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 MyVPS/keys/ca.crt
cert MyVPS/keys/client1.crt
key MyVPS/keys/client1.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 MyVPS/keys/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

#Set the MyVPS/logs:
status MyVPS/logs/client1-status
#log MyVPS/logs/client1.log
#log-append MyVPS/logs/client1.log


# Silence repeating messages
mute 20

The server has been allocated the following IP

tun0      Link encap:UNSPEC  HWaddr 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00
          inet addr:10.172.0.1  P-t-P:10.172.0.2  Mask:255.255.255.255
          UP POINTOPOINT RUNNING NOARP MULTICAST  MTU:1500  Metric:1
          RX packets:13 errors:0 dropped:0 overruns:0 frame:0
          TX packets:10 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:100
          RX bytes:1475 (1.4 KB)  TX bytes:1528 (1.5 KB)

The client has been allocated the following IP

Ethernet adapter OpenVPN:
        Connection-specific DNS Suffix  . : 
        IP Address. . . . . . . . . . . . : 10.172.0.6
        Subnet Mask . . . . . . . . . . . : 255.255.255.252
        Default Gateway . . . . . . . . . :

The routing table on the client is

Network Destination        Netmask          Gateway       Interface  Metric
   10.172.0.1  255.255.255.255       10.172.0.5      10.172.0.6	  1
   10.172.0.4  255.255.255.252       10.172.0.6      10.172.0.6	  30
   10.172.0.6  255.255.255.255        127.0.0.1       127.0.0.1	  30
   10.255.255.255  255.255.255.255       10.172.0.6      10.172.0.6	  30

What confuses me are the following:

The server has an IP of 10.172.0.1 & a mask of 255.255.255.255 while the client has an IP of 10.172.0.6 & a mask of 255.255.255.252. How can they belong to the same network? Surprisingly I can ping the server from the client without any problem.
The routing table on the client shows that the gateway to reach 10.172.0.1 is set as 10.172.0.5. But, I can't ping that gateway IP from the client.
An extra entry of 10.172.0.4 has appeared in the routing table while it is not also reachable. Where has it come from?
What does P-t-P:10.172.0.2 in server IP table mean?

Can anybody please clarify my doubts?

Mimiko

I see the OpenVPN server takes the config file from elsewhere than the one you posted. In posted config you use 10.8.0.0 for IP pool, but server uses 10.172.0.0/30

Holmes.Sherlock

Mimiko wroteI see the OpenVPN server takes the config file from elsewhere than the one you posted. In posted config you use 10.8.0.0 for IP pool, but server uses 10.172.0.0/30

I'm sorry. I was working with multiple similar config files with only difference in the address pool. I've corrected my original post.

Holmes.Sherlock

I've also tried

push "route 10.172.0.0 255.255.255.0"

But there is no difference observed.

Mimiko

Read manual for "--topology" option to understand why server has such IP.

It's strange that at client you don't have a route for 10.172.0.0/24. Please post OpenVPN server's and client's log.

Holmes.Sherlock

Here are all the SERVER logs:

ipp.txt

client1,10.172.0.4
client6,10.172.0.8

openvpn-status.log

OpenVPN CLIENT LIST
Updated,Sun Oct 16 07:58:44 2011
Common Name,Real Address,Bytes Received,Bytes Sent,Connected Since
client1,117.226.164.160:34142,5022,6116,Sun Oct 16 07:53:49 2011
ROUTING TABLE
Virtual Address,Common Name,Real Address,Last Ref
10.172.0.6,client1,117.226.164.160:34142,Sun Oct 16 07:53:59 2011
GLOBAL STATS
Max bcast/mcast queue length,0
END

openvpn.log

Sun Oct 16 07:36:56 2011 OpenVPN 2.1.0 x86_64-pc-linux-gnu [SSL] [LZO2] [EPOLL] [PKCS11] [MH] [PF_INET6] [eurephia] built on Jan 26 2010
Sun Oct 16 07:36:56 2011 NOTE: the current --script-security setting may allow this configuration to call user-defined scripts
Sun Oct 16 07:36:57 2011 Diffie-Hellman initialized with 1024 bit key
Sun Oct 16 07:36:57 2011 WARNING: file 'server/keys/TeamReboot.key' is group or others accessible
Sun Oct 16 07:36:57 2011 /usr/bin/openssl-vulnkey -q -b 1024 -m <modulus omitted>
Sun Oct 16 07:37:30 2011 TLS-Auth MTU parms [ L:1542 D:138 EF:38 EB:0 ET:0 EL:0 ]
Sun Oct 16 07:37:31 2011 ROUTE default_gateway=80.79.29.1
Sun Oct 16 07:37:31 2011 TUN/TAP device tun1 opened
Sun Oct 16 07:37:31 2011 TUN/TAP TX queue length set to 100
Sun Oct 16 07:37:31 2011 /sbin/ifconfig tun1 10.172.0.1 pointopoint 10.172.0.2 mtu 1500
Sun Oct 16 07:37:33 2011 /sbin/route add -net 10.172.0.0 netmask 255.255.255.0 gw 10.172.0.2
Sun Oct 16 07:37:34 2011 Data Channel MTU parms [ L:1542 D:1450 EF:42 EB:135 ET:0 EL:0 AF:3/1 ]
Sun Oct 16 07:37:35 2011 GID set to nobody
Sun Oct 16 07:37:35 2011 UID set to nobody
Sun Oct 16 07:37:35 2011 Socket Buffers: R=[124928->131072] S=[124928->131072]
Sun Oct 16 07:37:35 2011 UDPv4 link local (bound): [undef]
Sun Oct 16 07:37:35 2011 UDPv4 link remote: [undef]
Sun Oct 16 07:37:35 2011 MULTI: multi_init called, r=256 v=256
Sun Oct 16 07:37:35 2011 IFCONFIG POOL: base=10.172.0.4 size=62
Sun Oct 16 07:37:35 2011 IFCONFIG POOL LIST
Sun Oct 16 07:37:35 2011 client1,10.172.0.4
Sun Oct 16 07:37:35 2011 client6,10.172.0.8
Sun Oct 16 07:37:35 2011 Initialization Sequence Completed
Sun Oct 16 07:37:55 2011 MULTI: multi_create_instance called
Sun Oct 16 07:37:55 2011 80.79.23.36:50791 Re-using SSL/TLS context
Sun Oct 16 07:37:55 2011 80.79.23.36:50791 LZO compression initialized
Sun Oct 16 07:37:55 2011 80.79.23.36:50791 Control Channel MTU parms [ L:1542 D:138 EF:38 EB:0 ET:0 EL:0 ]
Sun Oct 16 07:37:55 2011 80.79.23.36:50791 Data Channel MTU parms [ L:1542 D:1450 EF:42 EB:135 ET:0 EL:0 AF:3/1 ]
Sun Oct 16 07:37:56 2011 80.79.23.36:50791 Local Options hash (VER=V4): '530fdded'
Sun Oct 16 07:37:56 2011 80.79.23.36:50791 Expected Remote Options hash (VER=V4): '41690919'
Sun Oct 16 07:37:56 2011 80.79.23.36:50791 TLS: Initial packet from [AF_INET]80.79.23.36:50791, sid=02e945b5 ad93ec1c
Sun Oct 16 07:37:56 2011 80.79.23.36:50791 VERIFY OK: depth=1, /O=Team_Reboot/CN=Team_Reboot/name=Team_Reboot
Sun Oct 16 07:37:56 2011 80.79.23.36:50791 VERIFY OK: depth=0, /O=Team_Reboot/CN=client1/name=client1
Sun Oct 16 07:37:56 2011 80.79.23.36:50791 Data Channel Encrypt: Cipher 'BF-CBC' initialized with 128 bit key
Sun Oct 16 07:37:56 2011 80.79.23.36:50791 Data Channel Encrypt: Using 160 bit message hash 'SHA1' for HMAC authentication
Sun Oct 16 07:37:56 2011 80.79.23.36:50791 Data Channel Decrypt: Cipher 'BF-CBC' initialized with 128 bit key
Sun Oct 16 07:37:56 2011 80.79.23.36:50791 Data Channel Decrypt: Using 160 bit message hash 'SHA1' for HMAC authentication
Sun Oct 16 07:37:56 2011 80.79.23.36:50791 Control Channel: TLSv1, cipher TLSv1/SSLv3 DHE-RSA-AES256-SHA, 1024 bit RSA
Sun Oct 16 07:37:56 2011 80.79.23.36:50791 [client1] Peer Connection Initiated with [AF_INET]80.79.23.36:50791
Sun Oct 16 07:37:56 2011 client1/80.79.23.36:50791 MULTI: Learn: 10.172.0.6 -> client1/80.79.23.36:50791
Sun Oct 16 07:37:56 2011 client1/80.79.23.36:50791 MULTI: primary virtual IP for client1/80.79.23.36:50791: 10.172.0.6
Sun Oct 16 07:37:58 2011 client1/80.79.23.36:50791 PUSH: Received control message: 'PUSH_REQUEST'
Sun Oct 16 07:37:58 2011 client1/80.79.23.36:50791 SENT CONTROL [client1]: 'PUSH_REPLY,route 10.172.0.0 255.255.255.0,route 10.172.0.1,topology net30,ping 10,ping-restart 120,ifconfig 10.172.0.6 10.172.0.5' (status=1)
Sun Oct 16 07:38:00 2011 read UDPv4 [ECONNREFUSED]: Connection refused (code=111)
Sun Oct 16 07:38:02 2011 read UDPv4 [ECONNREFUSED]: Connection refused (code=111)
Sun Oct 16 07:38:05 2011 read UDPv4 [ECONNREFUSED]: Connection refused (code=111)
Sun Oct 16 07:38:06 2011 MULTI: multi_create_instance called
Sun Oct 16 07:38:06 2011 117.226.220.116:24023 Re-using SSL/TLS context
Sun Oct 16 07:38:06 2011 117.226.220.116:24023 LZO compression initialized
Sun Oct 16 07:38:06 2011 117.226.220.116:24023 Control Channel MTU parms [ L:1542 D:138 EF:38 EB:0 ET:0 EL:0 ]
Sun Oct 16 07:38:06 2011 117.226.220.116:24023 Data Channel MTU parms [ L:1542 D:1450 EF:42 EB:135 ET:0 EL:0 AF:3/1 ]
Sun Oct 16 07:38:06 2011 117.226.220.116:24023 Local Options hash (VER=V4): '530fdded'
Sun Oct 16 07:38:06 2011 117.226.220.116:24023 Expected Remote Options hash (VER=V4): '41690919'
Sun Oct 16 07:38:06 2011 117.226.220.116:24023 TLS: Initial packet from [AF_INET]117.226.220.116:24023, sid=9e993471 b37c52f5
Sun Oct 16 07:38:07 2011 read UDPv4 [ECONNREFUSED]: Connection refused (code=111)
Sun Oct 16 07:38:09 2011 read UDPv4 [ECONNREFUSED]: Connection refused (code=111)
Sun Oct 16 07:38:11 2011 read UDPv4 [ECONNREFUSED]: Connection refused (code=111)
Sun Oct 16 07:38:11 2011 117.226.220.116:24023 VERIFY OK: depth=1, /O=Team_Reboot/CN=Team_Reboot/name=Team_Reboot
Sun Oct 16 07:38:11 2011 117.226.220.116:24023 VERIFY OK: depth=0, /O=Team_Reboot/CN=client1/name=client1
Sun Oct 16 07:38:12 2011 117.226.220.116:24023 Data Channel Encrypt: Cipher 'BF-CBC' initialized with 128 bit key
Sun Oct 16 07:38:12 2011 117.226.220.116:24023 Data Channel Encrypt: Using 160 bit message hash 'SHA1' for HMAC authentication
Sun Oct 16 07:38:12 2011 117.226.220.116:24023 Data Channel Decrypt: Cipher 'BF-CBC' initialized with 128 bit key
Sun Oct 16 07:38:12 2011 117.226.220.116:24023 Data Channel Decrypt: Using 160 bit message hash 'SHA1' for HMAC authentication
Sun Oct 16 07:38:13 2011 read UDPv4 [ECONNREFUSED]: Connection refused (code=111)
Sun Oct 16 07:38:13 2011 117.226.220.116:24023 Control Channel: TLSv1, cipher TLSv1/SSLv3 DHE-RSA-AES256-SHA, 1024 bit RSA
Sun Oct 16 07:38:13 2011 117.226.220.116:24023 [client1] Peer Connection Initiated with [AF_INET]117.226.220.116:24023
Sun Oct 16 07:38:13 2011 MULTI: new connection by client 'client1' will cause previous active sessions by this client to be dropped.  Remember to use the --duplicate-cn option if you want multiple clients using the same certificate or username to concurrently connect.
Sun Oct 16 07:38:13 2011 MULTI: Learn: 10.172.0.6 -> client1/117.226.220.116:24023
Sun Oct 16 07:38:13 2011 MULTI: primary virtual IP for client1/117.226.220.116:24023: 10.172.0.6
Sun Oct 16 07:38:15 2011 client1/117.226.220.116:24023 PUSH: Received control message: 'PUSH_REQUEST'
Sun Oct 16 07:38:15 2011 client1/117.226.220.116:24023 SENT CONTROL [client1]: 'PUSH_REPLY,route 10.172.0.0 255.255.255.0,route 10.172.0.1,topology net30,ping 10,ping-restart 120,ifconfig 10.172.0.6 10.172.0.5' (status=1)
Sun Oct 16 07:41:45 2011 read UDPv4 [ECONNREFUSED]: Connection refused (code=111)
Sun Oct 16 07:41:46 2011 read UDPv4 [ECONNREFUSED]: Connection refused (code=111)
Sun Oct 16 07:41:57 2011 read UDPv4 [ECONNREFUSED]: Connection refused (code=111)
Sun Oct 16 07:42:06 2011 read UDPv4 [ECONNREFUSED]: Connection refused (code=111)
Sun Oct 16 07:42:16 2011 read UDPv4 [ECONNREFUSED]: Connection refused (code=111)
Sun Oct 16 07:42:26 2011 read UDPv4 [ECONNREFUSED]: Connection refused (code=111)
Sun Oct 16 07:45:17 2011 client1/117.226.220.116:24023 [client1] Inactivity timeout (--ping-restart), restarting
Sun Oct 16 07:45:17 2011 client1/117.226.220.116:24023 SIGUSR1[soft,ping-restart] received, client-instance restarting
Sun Oct 16 07:53:49 2011 MULTI: multi_create_instance called
Sun Oct 16 07:53:49 2011 117.226.164.160:34142 Re-using SSL/TLS context
Sun Oct 16 07:53:49 2011 117.226.164.160:34142 LZO compression initialized
Sun Oct 16 07:53:49 2011 117.226.164.160:34142 Control Channel MTU parms [ L:1542 D:138 EF:38 EB:0 ET:0 EL:0 ]
Sun Oct 16 07:53:49 2011 117.226.164.160:34142 Data Channel MTU parms [ L:1542 D:1450 EF:42 EB:135 ET:0 EL:0 AF:3/1 ]
Sun Oct 16 07:53:49 2011 117.226.164.160:34142 Local Options hash (VER=V4): '530fdded'
Sun Oct 16 07:53:49 2011 117.226.164.160:34142 Expected Remote Options hash (VER=V4): '41690919'
Sun Oct 16 07:53:49 2011 117.226.164.160:34142 TLS: Initial packet from [AF_INET]117.226.164.160:34142, sid=7d1c497c 4e14977a
Sun Oct 16 07:53:56 2011 117.226.164.160:34142 VERIFY OK: depth=1, /O=Team_Reboot/CN=Team_Reboot/name=Team_Reboot
Sun Oct 16 07:53:56 2011 117.226.164.160:34142 VERIFY OK: depth=0, /O=Team_Reboot/CN=client1/name=client1
Sun Oct 16 07:53:58 2011 117.226.164.160:34142 Data Channel Encrypt: Cipher 'BF-CBC' initialized with 128 bit key
Sun Oct 16 07:53:58 2011 117.226.164.160:34142 Data Channel Encrypt: Using 160 bit message hash 'SHA1' for HMAC authentication
Sun Oct 16 07:53:58 2011 117.226.164.160:34142 Data Channel Decrypt: Cipher 'BF-CBC' initialized with 128 bit key
Sun Oct 16 07:53:58 2011 117.226.164.160:34142 Data Channel Decrypt: Using 160 bit message hash 'SHA1' for HMAC authentication
Sun Oct 16 07:53:59 2011 117.226.164.160:34142 Control Channel: TLSv1, cipher TLSv1/SSLv3 DHE-RSA-AES256-SHA, 1024 bit RSA
Sun Oct 16 07:53:59 2011 117.226.164.160:34142 [client1] Peer Connection Initiated with [AF_INET]117.226.164.160:34142
Sun Oct 16 07:53:59 2011 client1/117.226.164.160:34142 MULTI: Learn: 10.172.0.6 -> client1/117.226.164.160:34142
Sun Oct 16 07:53:59 2011 client1/117.226.164.160:34142 MULTI: primary virtual IP for client1/117.226.164.160:34142: 10.172.0.6
Sun Oct 16 07:54:01 2011 client1/117.226.164.160:34142 PUSH: Received control message: 'PUSH_REQUEST'
Sun Oct 16 07:54:01 2011 client1/117.226.164.160:34142 SENT CONTROL [client1]: 'PUSH_REPLY,route 10.172.0.0 255.255.255.0,route 10.172.0.1,topology net30,ping 10,ping-restart 120,ifconfig 10.172.0.6 10.172.0.5' (status=1)

Here is the CLIENT log

Sun Oct 16 13:37:07 2011 NOTE: --user option is not implemented on Windows
Sun Oct 16 13:37:07 2011 NOTE: --group option is not implemented on Windows
Sun Oct 16 13:37:07 2011 OpenVPN 2.2.0 Win32-MSVC++ [SSL] [LZO2] built on Apr 26 2011
Sun Oct 16 13:37:07 2011 NOTE: OpenVPN 2.1 requires '--script-security 2' or higher to call user-defined scripts or executables
Sun Oct 16 13:37:07 2011 LZO compression initialized
Sun Oct 16 13:37:07 2011 Control Channel MTU parms [ L:1542 D:138 EF:38 EB:0 ET:0 EL:0 ]
Sun Oct 16 13:37:07 2011 Socket Buffers: R=[8192->8192] S=[64512->64512]
Sun Oct 16 13:37:07 2011 Data Channel MTU parms [ L:1542 D:1450 EF:42 EB:135 ET:0 EL:0 AF:3/1 ]
Sun Oct 16 13:37:07 2011 Local Options hash (VER=V4): '41690919'
Sun Oct 16 13:37:07 2011 Expected Remote Options hash (VER=V4): '530fdded'
Sun Oct 16 13:37:07 2011 UDPv4 link local: [undef]
Sun Oct 16 13:37:07 2011 UDPv4 link remote: 80.79.29.203:1197
Sun Oct 16 13:37:08 2011 TLS: Initial packet from 80.79.29.203:1197, sid=8d9285fb d4bf02ad
Sun Oct 16 13:37:11 2011 VERIFY OK: depth=1, /O=Team_Reboot/CN=Team_Reboot/name=Team_Reboot
Sun Oct 16 13:37:11 2011 VERIFY OK: nsCertType=SERVER
Sun Oct 16 13:37:11 2011 VERIFY OK: depth=0, /O=Team_Reboot/CN=TeamReboot/name=TeamReboot
Sun Oct 16 13:37:16 2011 Data Channel Encrypt: Cipher 'BF-CBC' initialized with 128 bit key
Sun Oct 16 13:37:16 2011 Data Channel Encrypt: Using 160 bit message hash 'SHA1' for HMAC authentication
Sun Oct 16 13:37:16 2011 Data Channel Decrypt: Cipher 'BF-CBC' initialized with 128 bit key
Sun Oct 16 13:37:16 2011 Data Channel Decrypt: Using 160 bit message hash 'SHA1' for HMAC authentication
Sun Oct 16 13:37:16 2011 Control Channel: TLSv1, cipher TLSv1/SSLv3 DHE-RSA-AES256-SHA, 1024 bit RSA
Sun Oct 16 13:37:16 2011 [TeamReboot] Peer Connection Initiated with 80.79.29.203:1197
Sun Oct 16 13:37:19 2011 SENT CONTROL [TeamReboot]: 'PUSH_REQUEST' (status=1)
Sun Oct 16 13:37:19 2011 PUSH: Received control message: 'PUSH_REPLY,route 10.172.0.0 255.255.255.0,route 10.172.0.1,topology net30,ping 10,ping-restart 120,ifconfig 10.172.0.6 10.172.0.5'
Sun Oct 16 13:37:19 2011 OPTIONS IMPORT: timers and/or timeouts modified
Sun Oct 16 13:37:19 2011 OPTIONS IMPORT: --ifconfig/up options modified
Sun Oct 16 13:37:19 2011 OPTIONS IMPORT: route options modified
Sun Oct 16 13:37:19 2011 ROUTE default_gateway=117.226.164.160
Sun Oct 16 13:37:19 2011 TAP-WIN32 device [OpenVPN] opened: \\.\Global\{4ED76793-07D4-4820-B660-771A9C4EBE7E}.tap
Sun Oct 16 13:37:19 2011 TAP-Win32 Driver Version 9.8 
Sun Oct 16 13:37:19 2011 TAP-Win32 MTU=1500
Sun Oct 16 13:37:19 2011 Notified TAP-Win32 driver to set a DHCP IP/netmask of 10.172.0.6/255.255.255.252 on interface {4ED76793-07D4-4820-B660-771A9C4EBE7E} [DHCP-serv: 10.172.0.5, lease-time: 31536000]
Sun Oct 16 13:37:19 2011 Successful ARP Flush on interface [589827] {4ED76793-07D4-4820-B660-771A9C4EBE7E}
Sun Oct 16 13:37:24 2011 TEST ROUTES: 2/2 succeeded len=2 ret=1 a=0 u/d=up
Sun Oct 16 13:37:24 2011 C:\WINDOWS\system32\route.exe ADD 10.172.0.0 MASK 255.255.255.0 10.172.0.5
Sun Oct 16 13:37:24 2011 Route addition via IPAPI succeeded [adaptive]
Sun Oct 16 13:37:24 2011 C:\WINDOWS\system32\route.exe ADD 10.172.0.1 MASK 255.255.255.255 10.172.0.5
Sun Oct 16 13:37:24 2011 Route addition via IPAPI succeeded [adaptive]
Sun Oct 16 13:37:24 2011 Initialization Sequence Completed

Please let me know if you need some more info.

Mimiko

push "route 10.172.0.0 255.255.255.0"

Don't use this in OpenVPN server's config. This route is implicit.

Check routing table on client when the OpenVPN is disconnected.
Delete ipp.txt file.
Run OpenVPN client with elevated rights.

Holmes.Sherlock

Mimiko wrote
push "route 10.172.0.0 255.255.255.0"

Don't use this in OpenVPN server's config. This route is implicit.

Delete ipp.txt file.

Run OpenVPN client with elevated rights.

All three done. I'm running the client from a Windows XP box with Admin privileges. Still no difference.

Check routing table on client when the OpenVPN is disconnected.

Routing table before connecinng to VPN

Active Routes:
Network Destination Netmask Gateway Interface Metric
0.0.0.0 0.0.0.0 <My Public IP> <My Public IP> 1
<My Public IP> 255.255.255.255 127.0.0.1 127.0.0.1 50
117.255.255.255 255.255.255.255 <My Public IP> <My Public IP> 50
127.0.0.0 255.0.0.0 127.0.0.1 127.0.0.1 1
224.0.0.0 240.0.0.0 <My Public IP> <My Public IP> 1
255.255.255.255 255.255.255.255 <My Public IP> 90003 1
255.255.255.255 255.255.255.255 <My Public IP> 10006 1
255.255.255.255 255.255.255.255 <My Public IP> <My Public IP> 1
255.255.255.255 255.255.255.255 <My Public IP> 2 1
Default Gateway: <My Public IP>
===========================================================================
Persistent Routes:
None

Routing table after connecinng to VPN

Active Routes:
Network Destination Netmask Gateway Interface Metric
0.0.0.0 0.0.0.0 <My Public IP> <My Public IP> 1
10.172.0.0 255.255.255.0 10.172.0.5 10.172.0.6 1
10.172.0.1 255.255.255.255 10.172.0.5 10.172.0.6 1
10.172.0.4 255.255.255.252 10.172.0.6 10.172.0.6 30
10.172.0.6 255.255.255.255 127.0.0.1 127.0.0.1 30
10.255.255.255 255.255.255.255 10.172.0.6 10.172.0.6 30
<My Public IP> 255.255.255.255 127.0.0.1 127.0.0.1 50
117.255.255.255 255.255.255.255 <My Public IP> <My Public IP> 50
127.0.0.0 255.0.0.0 127.0.0.1 127.0.0.1 1
224.0.0.0 240.0.0.0 10.172.0.6 10.172.0.6 30
224.0.0.0 240.0.0.0 <My Public IP> <My Public IP> 1
255.255.255.255 255.255.255.255 10.172.0.6 10.172.0.6 1
255.255.255.255 255.255.255.255 <My Public IP> 10006 1
255.255.255.255 255.255.255.255 <My Public IP> <My Public IP> 1
255.255.255.255 255.255.255.255 <My Public IP> 2 1
Default Gateway: <My Public IP>
===========================================================================
Persistent Routes:
None

Holmes.Sherlock

The most interesting line in the posted server log is:

Sun Oct 16 07:54:01 2011 client1/117.226.164.160:34142 SENT CONTROL [client1]: 'PUSH_REPLY,route 10.172.0.0 255.255.255.0,route 10.172.0.1,topology net30,ping 10,ping-restart 120,ifconfig 10.172.0.6 10.172.0.5' (status=1)

Can anybody explain how can PUSH_REPLY,route 10.172.0.0 255.255.255.0 & topology net30 coexist?

Mimiko

I see that the routing table is correct.

Can anybody explain how can PUSH_REPLY,route 10.172.0.0 255.255.255.0 & topology net30 coexist?

Its the same how you can have the mask on the public interface like /24 or /26 or even /30 and /32. And still access any internet IP with any mask. The net30 topology is only for client and server to interact, but packets can contain ip's for /24 mask.

Holmes.Sherlock

Mimiko wrote Its the same how you can have the mask on the public interface like /24 or /26 or even /30 and /32. And still access any internet IP with any mask. The net30 topology is only for client and server to interact, but packets can contain ip's for /24 mask.

I think that /30 topology is causing my problem. Actually there is one more private network(10.8.0.0/255.255.255.0) connected to the OpenVPN server box. What I'm trying is to redirect all the traffic towards 10.8.0.0/255.255.255.0 from OpenVPN client box via 10.172.0.0/255.255.255.0 tunnel. I tried

route add 10.172.0.0 mask 255.255.255.0 10.172.0.1 metric 1

But this is failing with the error message saying that GATEWAY (i.e. 10.172.0.1) does not lie on the same network as the chosen interface (i.e. 10.172.0.6/255.255.255.252). What can I do?

Holmes.Sherlock

Mimiko wroteI see that the routing table is correct.
Its the same how you can have the mask on the public interface like /24 or /26 or even /30 and /32. And still access any internet IP with any mask. The net30 topology is only for client and server to interact, but packets can contain ip's for /24 mask.

I apologize, but this is not that clear to me. Can you please elaborate a bit?

Holmes.Sherlock

Just for the record,
http://forums.openvpn.net/topic7711.html explains a bit of my doubts.

Holmes.Sherlock

But using

topology subnet

assigns my client 10.172.0.4 instead of 10.172.0.2 as told in the thread referred previously.

Mimiko

You are making thign harder. If it works, don't modify the routing if you don't know what you whant to achieve.

route add 10.172.0.0 mask 255.255.255.0 10.172.0.1 metric 1

Why you are still trying to add this route to the client? This route is added automatically by the OpenVPN client. See your routing table.
And yes, it will fall with error, because clients IP is not in the same network mask. Your client gets 10.172.0.6, and the gw for this IP is 10.172.0.5, and the right command will be:

route add 10.172.0.0 mask 255.255.255.0 10.172.0.5

10.172.0.5 is bound with 10.172.0.1 by the OpenVPN server.

topology subnet
assigns my client 10.172.0.4 instead of 10.172.0.2 as told in the thread referred previously.

In this configuration, server wil have 10.172.0.1 and clients will get any IP from 10.172.0.2 to 10.172.0.254. But the client gets the IP 0.4 because this association is writed in ipp.txt file. Delete it and the client will get the next free IP.
Usualy, setting this kind of topology is not required.

Holmes.Sherlock

Mimiko wrote In this configuration, server wil have 10.172.0.1 and clients will get any IP from 10.172.0.2 to 10.172.0.254. But the client gets the IP 0.4 because this association is writed in ipp.txt file. Delete it and the client will get the next free IP.

Deleting ipp.txt & restarting OpenVPN assigned my client 10.172.0.2/255.255.255.0, as expected.

Usualy, setting this kind of topology is not required.

Why do you say so?

Mimiko

Why do you say so?

net30 topology is more secure than subnet, to isolate different clients access each other.

Holmes.Sherlock

Mimiko wrote
Why do you say so?
net30 topology is more secure than subnet, to isolate different clients access each other.

But

topology subnet

solves my problem. I had another 10.8.0.0/255.255.255.0 private network connected to my OpenVPN server box. I wanted to access this network from my OpenVPN client, which is in a 10.172.0.0/255.255.255.0 network with the Server. The scenario is something like this:

All are /24 networks. I wanted to access 10.8.0.1/30 from 10.172.0.2/30. I masqueraded the traffic on the OpenVPN server as follows

echo 1 > /proc/sys/net/ipv4/ip_forward

iptables -I FORWARD -i tun+ -j ACCEPT
iptables -I FORWARD -o tun+ -j ACCEPT

iptables -t nat -I POSTROUTING -o tun0 -j MASQUERADE

& set up a route on OpenVPN client as follows:

route add 10.8.0.0 mask 255.255.255.0 10.172.0.1 metric 1

& I could access the 10.8.0.1 box from 10.172.0.2.

Now please let me know if there any trick to create the scenario depicted above with topology net30.

Mimiko

You don't need to add route on client manually, just add to your OpenVPN server's config:

push "route 10.8.0.0 25.255.255.0"

You don't even need to masquarade, only enable forwarding and input/output rules for tun adapter. See http://www.openvpn.net/index.php/open-source/documentation/howto.html#scope

Holmes.Sherlock

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