Pings Work But Broadcast Traffic Doesn't

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gevely
OpenVpn Newbie
Posts: 3
Joined: Wed Mar 06, 2013 8:20 am

Pings Work But Broadcast Traffic Doesn't

Post by gevely » Wed Mar 06, 2013 9:58 am

I am new to OpenVPN and was wondering if someone could help me with the following configuration problem. I am able to ping between all clients and the server, that are connected to OpenVPN but I don't appear to be able to receive UDP broadcasts from a client, on any other clients connected to the OpenVPN Server. My configuration is as follows.

OpenVPN Server running on a VPS running CentOS 6.3 with a static IP Address of 37.122.210.15 and setting up the OpenVPN network on 192.168.50.x using the following configuration file:

Code: Select all

local 37.122.210.15

port 1194

;proto tcp
proto udp

;dev tap
dev tun

;dev-node MyTap

ca /etc/openvpn/easy-rsa/2.0/keys/ca.crt
cert /etc/openvpn/easy-rsa/2.0/keys/VPNSERVER.crt
key /etc/openvpn/easy-rsa/2.0/keys/VPNSERVER.key  # This file should be kept secret

dh /etc/openvpn/easy-rsa/2.0/keys/dh1024.pem

server 192.168.50.0 255.255.255.0

ifconfig-pool-persist ipp.txt

push "route 192.168.50.0 255.255.255.0"

route 192.168.50.0 255.255.255.0

;client-config-dir ccd

;learn-address ./script

;push "redirect-gateway"
;push "redirect-gateway local def1"

;push "dhcp-option DNS 10.8.0.1"
;push "dhcp-option WINS 10.8.0.1"

client-to-client

;duplicate-cn

keepalive 10 120

;cipher BF-CBC        # Blowfish (default)
;cipher AES-128-CBC   # AES
;cipher DES-EDE3-CBC  # Triple-DES

comp-lzo

max-clients 100

;user nobody
;group nobody

persist-key
persist-tun

status openvpn-status.log

;log         openvpn.log
;log-append  openvpn.log

verb 3

;mute 20
Client 1 running on a Windows XP machine in a local subnet with physical IP 192.168.20.10 connecting to the OpenVPN server via a 3G dongle with the following configuration file:

Code: Select all

##############################################
# 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 192.168.10.3 1194
remote 37.122.210.15 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 "C:\\Program Files\\OpenVPN\\keys\\ca.crt"
cert "C:\\Program Files\\OpenVPN\\keys\\RemoteV2EMS.crt"
key "C:\\Program Files\\OpenVPN\\keys\\RemoteV2EMS.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
Client 2 running on a Windows XP machine in a local subnet with physical IP 192.168.10.10 connecting to the OpenVPN server via a router with 3G connectivity to the internet using the following OpenVPN configuration file:

Code: Select all

##############################################
# 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 192.168.10.3 1194
remote 37.122.210.15 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 "C:\\Program Files\\OpenVPN\\keys\\ca.crt"
cert "C:\\Program Files\\OpenVPN\\keys\\IMS.crt"
key "C:\\Program Files\\OpenVPN\\keys\\IMS.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
The server is allocated the IP 192.168.50.1, Client 1 is allocated the IP 192.168.50.10 and Client 2 is allocated the IP 192.168.50.14. I am able to ping from each of these addresses to any of the other and get the ping responses successfully. However, when Client 1 sends a broadcast message over UDP it does not appear to be received at Client 2.

Can anyone suggest what I should change in order for this to work

Thanks in advance
Gary

User avatar
maikcat
Forum Team
Posts: 4200
Joined: Wed Jan 12, 2011 9:23 am
Location: Athens,Greece
Contact:

Re: Pings Work But Broadcast Traffic Doesn't

Post by maikcat » Wed Mar 06, 2013 12:25 pm

hi there,

just to remind you that tun is a layer 3 device which DONT
forward broadcast/multicast packets.

Regards
Michael.
Amiga 500 , Zx +2 owner
Long live Dino Dini (Kick off 2 Creator)

Inflammable means flammable? (Dr Nick Riviera,Simsons Season13)

"objects in mirror are losing"

gevely
OpenVpn Newbie
Posts: 3
Joined: Wed Mar 06, 2013 8:20 am

Re: Pings Work But Broadcast Traffic Doesn't

Post by gevely » Wed Mar 06, 2013 7:24 pm

Thanks for the reply Michael.

Does this mean that my only option is to change to a bridged rather than routed configuration?

Thanks
Gary

User avatar
maikcat
Forum Team
Posts: 4200
Joined: Wed Jan 12, 2011 9:23 am
Location: Athens,Greece
Contact:

Re: Pings Work But Broadcast Traffic Doesn't

Post by maikcat » Thu Mar 07, 2013 8:09 am

AFAIK yes...

regards
Michael.
Amiga 500 , Zx +2 owner
Long live Dino Dini (Kick off 2 Creator)

Inflammable means flammable? (Dr Nick Riviera,Simsons Season13)

"objects in mirror are losing"

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