openvpn

Wed Apr 24 07:46:02 UTC 2019

Hello Doug,

I am suspect of the system not being configured as a router, aka sysctl
values should be set to net.inet.ip.forwarding: 1 and
net.inet6.ip6.forwarding: 1 (for v6 traffic) to allow packets to be
forwarded. If you add /etc/rc.conf, file /etc/sysctl.conf,
/boot/loader.conf and pf.conf or ipfw configuration it will help greatly in
understanding your configuration if this doesn't work.

Best regards,
Richard Gallamore

On Tue, Apr 23, 2019 at 10:43 PM Doug Hardie <bc979 at lafn.org> wrote:

> > On 23 April 2019, at 19:16, Karl Denninger <karl at denninger.net> wrote:
> >
> >
> > On 4/22/2019 19:53, Doug Hardie wrote:
> >> I am trying to setup an openvpn server on my home network.  Home
> machines are all running FBSD 12.0 Release.  openvpn was installed as a
> package.  The results are quite confusing.  Ping from an external device
> works correctly to all the home machines.  I can use tcpdump to see the
> request packets arriving at the openvpn server, being sent to the recipient
> machine, the response packets being sent from the recipient machine to the
> openvpn server, and then sent to the external device. The external device
> shows that the response was received with a reasonable response time given
> that it is a cell phone.
> >>
> >> However, when I try to access a web page on any of the servers, I see
> the same set of packets via tcpdump.  In addition if I run ktrace on the
> openvpn server, I see the encrypted packets from the client being
> received.  The decrypted packets sent to the home server.  The unencrypted
> response from the home server, and the encrypted response sent to the
> phone.  However, the phone says that the server dropped the connection, or
> it shows a blank page.
> >>
> >> My first thought was that there was an encryption issue, but if that
> were the case, ping would not work.  Checking the ping packets shows that
> they are encrypted between the phone and the openvpn server.  Likewise a
> routing issue in the home network does not seem to be the problem for the
> same reason.  All the info I have found on the web about vpn indicates that
> a ping test should be sufficient.  But, in this case it is not.
> >>
> >> Any ideas on how to track down the problem, or fix it?  Thanks,
> >>
> >> -- Doug
> >
> > IMHO -- post your configuration file to the list....
> >
> > I use OpenVPN with ipfw's internal NAT and it works fine, but the config
> > file is a bit wonky and if you get it wrong you'll either have no DNS on
> > the client or packets won't get routed.  Either way the connection comes
> > up but it doesn't work.
> >
>
> mail# more server.conf
> #################################################
> # 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.                        #
> #                                               #
> # 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 1194
>
> # 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
>
> # 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 ca.pem
> cert vpn_server.pem
> key vpn_server.key  # This file should be kept secret
>
> # Diffie hellman parameters.
> # Generate your own with:
> #   openssl dhparam -out dh2048.pem 2048
> dh dh2048.pem
>
> # Network topology
> # Should be subnet (addressing via IP)
> # unless Windows clients v2.0.9 and lower have to
> # be supported (then net30, i.e. a /30 per client)
> # Defaults to net30 (not recommended)
> ;topology subnet
>
> # 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 10.8.0.0 255.255.255.0
>
> # 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
>
> # Configure server mode for ethernet bridging
> # using a DHCP-proxy, where clients talk
> # to the OpenVPN server-side DHCP server
> # to receive their IP address allocation
> # and DNS server addresses.  You must first use
> # your OS's bridging capability to bridge the TAP
> # interface with the ethernet NIC interface.
> # Note: this mode only works on clients (such as
> # Windows), where the client-side TAP adapter is
> # bound to a DHCP client.
> ;server-bridge
>
> # 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"
> push "route 10.0.1.0 255.255.255.0"
>
> # 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
> # or bridge the TUN/TAP interface to the internet
> # in order for this to work properly).
> push "redirect-gateway def1 bypass-dhcp"
>
> # Certain Windows-specific network settings
> # can be pushed to clients, such as DNS
> # or WINS server addresses.  CAVEAT:
> # http://openvpn.net/faq.html#dhcpcaveats
> # The addresses below refer to the public
> # DNS servers provided by opendns.com.
> ;push "dhcp-option DNS 208.67.222.222"
> push "dhcp-option DNS 10.0.1.230"
>
> # 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.
> # Note that 2.4 client/server will automatically
> # negotiate AES-256-GCM in TLS mode.
> # See also the ncp-cipher option in the manpage
> cipher AES-256-CBC
>
> # Enable compression on the VPN link and push the
> # option to the client (2.4+ only, for earlier
> # versions see below)
> compress lz4-v2
> push "compress lz4-v2"
>
> # For compression compatible with older clients use comp-lzo
> # 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 5
>
> # 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
> verb 4
>
> # Silence repeating messages.  At most 20
> # sequential messages of the same message
> # category will be output to the log.
> ;mute 20
>
> # Notify the client that when the server restarts so it
> # can automatically reconnect.
> explicit-exit-notify 1
> mail#
>
>
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