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Re: [Openvpn-users] Gentoo Server 2.0.7 WinXP client 2.0.7 can't ping behind server


  • Subject: Re: [Openvpn-users] Gentoo Server 2.0.7 WinXP client 2.0.7 can't ping behind server
  • From: "J. Patrick Campbell" <patrick@xxxxxxxxxxxxxxxxxx>
  • Date: Thu, 26 Oct 2006 03:55:35 -0400

We have found that if a machine on the vpn server LAN pings the
client, then gets the icmp redirect, the client can then access that
machine. Not before.
How can I fix this?

On 10/9/06, J. Patrick Campbell <patrick@xxxxxxxxxxxxxxxxxx> wrote:
> The remote client can't ping behind the server, but clients behind the
> server can ping the remote client.
> my lan setup:
> 10.74.78.0/24
>
> 10.74.78.160 vpn server
> 10.74.78.1 ipcop firewall/router with a static route pointing vpn
> subnet to vpn server
> 10.74.0.0/24 vpn subnet
>
>
> Win xp client is behind a linksys router, subnet 192.168.1.1/24
> he dials in to the vpn and gets ip of 10.74.0.6
>
> when i ask him to tracert to any machine behind the openvpn server, he
> gets this:
>  Tracing route to 10.74.78.111 over a maximum of 30 ho
>
>
>
>   1    27 ms    23 ms    21 ms  10.74.0.1
>
>   2     *        *        *     Request timed out.
>
>   3     *        *        *     Request timed out.
>
>
> I think the problem lies there, in that he should be seeing 10.74.0.5
> as his first hop, not 10.74.0.1 but I cannot figure out where this ip
> is coming from.
>
> here is his routing table
>
> ===========================================================================
> Interface List
> 0x1 ........................... MS TCP Loopback interface
> 0x2 ...00 ff d5 f0 48 cc ...... TAP-Win32 Adapter V8
> 0x10004 ...00 07 e9 09 c7 2c ...... Intel(R) PRO/1000 MT Desktop Adapter
> ===========================================================================
> ===========================================================================
> Active Routes:
> Network Destination        Netmask          Gateway       Interface  Metric
>           0.0.0.0          0.0.0.0      192.168.1.1   192.168.1.245       10
>         10.74.0.1  255.255.255.255        10.74.0.5       10.74.0.6       1
>         10.74.0.4  255.255.255.252        10.74.0.6       10.74.0.6       30
>         10.74.0.6  255.255.255.255        127.0.0.1       127.0.0.1       30
>        10.74.78.0    255.255.255.0        10.74.0.5       10.74.0.6       1
>    10.255.255.255  255.255.255.255        10.74.0.6       10.74.0.6       30
>         127.0.0.0        255.0.0.0        127.0.0.1       127.0.0.1       1
>       192.168.1.0    255.255.255.0    192.168.1.245   192.168.1.245       10
>     192.168.1.245  255.255.255.255        127.0.0.1       127.0.0.1       10
>     192.168.1.255  255.255.255.255    192.168.1.245   192.168.1.245       10
>         224.0.0.0        240.0.0.0        10.74.0.6       10.74.0.6       30
>         224.0.0.0        240.0.0.0    192.168.1.245   192.168.1.245       10
>   255.255.255.255  255.255.255.255        10.74.0.6       10.74.0.6       1
>   255.255.255.255  255.255.255.255    192.168.1.245   192.168.1.245       1
> Default Gateway:       192.168.1.1
> ===========================================================================
> Persistent Routes:
>   None
>
> here's my server config
> vpn openvpn # cat lowmips.conf
>     # 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 53500
>
>     # 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 /etc/openvpn/easy-rsa/keys/ca.crt
>     cert /etc/openvpn/easy-rsa/keys/server.crt
>     key /etc/openvpn/easy-rsa/keys/server.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 /etc/openvpn/easy-rsa/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 10.74.0.0 255.255.255.0
>
>     # 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 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 (10.74.0.0/255.255.255.0)
>     # back to the OpenVPN server.
>     push "route 10.74.78.0 255.255.255.0"
>     ;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 ta.key 0 # 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 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         openvpn.log
>     ;log-append  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
> -------------------------------------------------------------------------------------------------------------------
>
> please let me know if you need any more information.
>
> Thanks,
>
> Patrick
>
> --
> http://patrickcampbell.us/
> Visit for my Blog, Photos and More!
>


-- 
http://patrickcampbell.us/
Visit for my Blog, Photos and More!
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