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a973ead642
Added general theoretical IPsec documentation. Changed site-to-site IPsec VPN documentation. Added steps for configuration. Added documentation for troubleshooting site-to-site IPsec VPN.
423 lines
16 KiB
ReStructuredText
423 lines
16 KiB
ReStructuredText
.. _vpn-dmvpn:
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#####
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DMVPN
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#####
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:abbr:`DMVPN (Dynamic Multipoint Virtual Private Network)` is a dynamic
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:abbr:`VPN (Virtual Private Network)` technology originally developed by Cisco.
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While their implementation was somewhat proprietary, the underlying
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technologies are actually standards based. The three technologies are:
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* :abbr:`NHRP (Next Hop Resolution Protocol)` :rfc:`2332`
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* :abbr:`mGRE (Multipoint Generic Routing Encapsulation)` :rfc:`1702`
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* :abbr:`IPSec (IP Security)` - too many RFCs to list, but start with
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:rfc:`4301`
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NHRP provides the dynamic tunnel endpoint discovery mechanism (endpoint
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registration, and endpoint discovery/lookup), mGRE provides the tunnel
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encapsulation itself, and the IPSec protocols handle the key exchange, and
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crypto mechanism.
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In short, DMVPN provides the capability for creating a dynamic-mesh VPN
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network without having to pre-configure (static) all possible tunnel end-point
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peers.
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.. note:: DMVPN only automates the tunnel endpoint discovery and setup. A
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complete solution also incorporates the use of a routing protocol. BGP is
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particularly well suited for use with DMVPN.
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.. figure:: /_static/images/vpn_dmvpn_topology01.png
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:scale: 40 %
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:alt: Baseline DMVPN topology
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Baseline DMVPN topology
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*************
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Configuration
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*************
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Tunnel interface configuration
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==============================
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NHRP never handles routing of prefixes itself. You need to run some real routing
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protocol (e.g. BGP) to advertise routes over the tunnels. What nhrpd does it
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establishes ‘shortcut routes’ that optimizes the routing protocol to avoid going
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through extra nodes in NBMA GRE mesh.
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NHRP does route NHRP domain addresses individually using per-host prefixes.
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This is similar to Cisco FlexVPN, but in contrast to opennhrp which uses
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a generic subnet route.
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To create NBMA GRE tunnel you might use the following:
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.. code-block:: none
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set interfaces tunnel tun100 address '10.0.0.1/32'
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set interfaces tunnel tun100 enable-multicast
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set interfaces tunnel tun100 encapsulation 'gre'
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set interfaces tunnel tun100 ip adjust-mss '1360'
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set interfaces tunnel tun100 mtu '1400'
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set interfaces tunnel tun100 parameters ip key '42'
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set interfaces tunnel tun100 source-interface 'eth0'
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* Please refer to the :ref:`tunnel-interface` documentation for the individual
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tunnel related options.
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.. note:: The IP-address is assigned as host prefix to tunnel interface.
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NHRP will automatically create additional host routes pointing to tunnel interface
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when a connection with these hosts is established.
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The tunnel interface subnet prefix should be announced by routing protocol
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from the hub nodes (e.g. BGP ‘network’ announce). This allows the routing
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protocol to decide which is the closest hub and determine the relay hub on
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prefix basis when direct tunnel is not established.
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NHRP protocol configuration
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==============================
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.. cfgcmd:: set protocols nhrp tunnel <tunnel> authentication <secret>
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Enables Cisco style authentication on NHRP packets. This embeds the
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plaintext password to the outgoing NHRP packets. Maximum length of
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the password is 8 characters.
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.. cfgcmd:: set protocols nhrp tunnel <tunnel> holdtime <timeout>
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Holdtime is the number of seconds that have to pass before stopping to
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advertise an NHRP NBMA address as valid. It also controls how often NHRP
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registration requests are sent. By default registrations are sent every
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one third of the holdtime
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.. cfgcmd:: set protocols nhrp tunnel <tunnel> map tunnel-ip <tunnel-ip>
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nbma <nbma-ip>
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* **tunnel-ip** - Tunnel ip address in format **x.x.x.x**.
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* **nbma-ip** - NBMA ip address in format **x.x.x.x** or **local**
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Map an IP address of a station to the station’s NBMA address.
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.. cfgcmd:: set protocols nhrp tunnel <tunnel> mtu <mtu>
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Configure NHRP advertised MTU.
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.. cfgcmd:: set protocols nhrp tunnel <tunnel> multicast <nbma-ip>
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* **nbma-ip** - NBMA ip address in format **x.x.x.x** or **dynamic**
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Sends multicast packets to the specified NBMA address. If dynamic is specified
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then destination NBMA address (or addresses) are learnt dynamically.
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.. cfgcmd:: set protocols nhrp tunnel <tunnel> network-id <network-id>
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* **network-id** - NHRP network id <1-4294967295>
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Enable NHRP on this interface and set the interface’s network ID. The network ID
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is used to allow creating multiple nhrp domains on a router when multiple interfaces
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are configured on the router. Interfaces configured with the same ID are part of the
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same logical NBMA network. The ID is a local only parameter and is not sent to other
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NHRP nodes and so IDs on different nodes do not need to match. When NHRP packets are
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received on an interface they are assigned to the local NHRP domain for that interface.
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.. cfgcmd:: set protocols nhrp tunnel <tunnel> nhs tunnel-ip <tunnel-ip> nbma <nbma-ip>
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* **tunnel-ip** - Tunnel ip address in format **x.x.x.x** or **dynamic**
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* **nbma-ip** - NBMA ip address in format **x.x.x.x**
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Configure the Next Hop Server address and its NBMA address. If dynamic is specified
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then Next Hop Server can have dynamic address which maps to its NBMA address.
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.. cfgcmd:: set protocols nhrp tunnel <tunnel> redirect
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This enable redirect replies on the NHS similar to ICMP redirects except this is
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managed by the nhrp protocol. This setting allows spokes to communicate with each
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others directly.
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.. cfgcmd:: set protocols nhrp tunnel <tunnel> registration-no-unique
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Allow the client to not set the unique flag in the NHRP packets. This is useful when
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a station has a dynamic IP address that could change over time.
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.. cfgcmd:: set protocols nhrp tunnel <tunnel> shortcut
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Enable shortcut (spoke-to-spoke) tunnels to allow NHC to talk to each others directly
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after establishing a connection without going through the hub.
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IPSEC configuration
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==============================
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* Please refer to the :ref:`ipsec_general` documentation for the individual IPSec
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related options.
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.. note:: NHRP daemon based on FRR nhrpd. It controls IPSEC. That's why 'close-action'
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parameter in IKE configuration always is set to 'close' and 'dead-peer-detection action'
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always is set to 'clear'.
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.. cfgcmd:: set vpn ipsec profile <profile-name> authentication mode pre-shared-secret
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Set preshared secret mode authentication
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.. cfgcmd:: set vpn ipsec profile <profile-name> authentication pre-shared-secret <secret>
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Set preshared secret
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.. cfgcmd:: set vpn ipsec profile <profile-name> bind tunnel <tunnel name>
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Bind IPSEC profile to the specific tunnel interface.
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.. cfgcmd:: set vpn ipsec profile <profile-name> esp-group 'ESP-HUB'
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Map ESP group to IPSEC profile
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.. cfgcmd:: set vpn ipsec profile <profile-name> ike-group 'IKE-HUB'
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Map IKE group to IPSEC profile
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**********
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Monitoring
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**********
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.. opcmd:: show ip nhrp cache
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Forwarding cache information.
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.. opcmd:: show ip nhrp nhs
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Next hop server information.
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.. opcmd:: show ip nhrp shortcut
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Shortcut information.
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*******
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Example
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*******
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This blueprint uses VyOS as the DMVPN Hub and Cisco IOSv 15.5(3)M and VyOS as
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multiple spoke sites.
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.. figure:: /_static/images/blueprint-dmvpn.png
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:width: 70%
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:align: center
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:alt: DMVPN Network Topology Diagram
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DMVPN Network Topology Diagram
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Each node (Hub and Spoke) uses an IP address from the network 10.0.0.0/24.
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The below referenced IP address `192.168.0.2` is used as example address
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representing a global unicast address under which the HUB can be contacted by
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each and every individual spoke.
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.. _dmvpn:example_configuration:
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Configuration
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=============
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Hub
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---
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VyOS-HUB-1
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^^^^^^^^^^
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.. code-block:: none
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set interfaces ethernet eth0 address '192.168.0.2/30'
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set interfaces tunnel tun100 address '10.0.0.100/32'
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set interfaces tunnel tun100 enable-multicast
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set interfaces tunnel tun100 encapsulation 'gre'
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set interfaces tunnel tun100 parameters ip key '42'
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set interfaces tunnel tun100 source-interface 'eth0'
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set protocols nhrp tunnel tun100 authentication 'test123'
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set protocols nhrp tunnel tun100 holdtime '300'
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set protocols nhrp tunnel tun100 multicast 'dynamic'
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set protocols nhrp tunnel tun100 network-id '1'
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set protocols nhrp tunnel tun100 redirect
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set protocols nhrp tunnel tun100 registration-no-unique
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set protocols static route 0.0.0.0/0 next-hop 192.168.0.1
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set vpn ipsec esp-group ESP-HUB lifetime '1800'
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set vpn ipsec esp-group ESP-HUB mode 'transport'
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set vpn ipsec esp-group ESP-HUB pfs 'dh-group2'
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set vpn ipsec esp-group ESP-HUB proposal 1 encryption 'aes256'
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set vpn ipsec esp-group ESP-HUB proposal 1 hash 'sha1'
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set vpn ipsec ike-group IKE-HUB key-exchange 'ikev1'
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set vpn ipsec ike-group IKE-HUB lifetime '3600'
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set vpn ipsec ike-group IKE-HUB proposal 1 dh-group '2'
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set vpn ipsec ike-group IKE-HUB proposal 1 encryption 'aes256'
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set vpn ipsec ike-group IKE-HUB proposal 1 hash 'sha1'
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set vpn ipsec interface 'eth0'
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set vpn ipsec profile NHRPVPN authentication mode 'pre-shared-secret'
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set vpn ipsec profile NHRPVPN authentication pre-shared-secret 'secret'
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set vpn ipsec profile NHRPVPN bind tunnel 'tun100'
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set vpn ipsec profile NHRPVPN esp-group 'ESP-HUB'
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set vpn ipsec profile NHRPVPN ike-group 'IKE-HUB'
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.. note:: Setting this up on AWS will require a "Custom Protocol Rule" for
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protocol number "47" (GRE) Allow Rule in TWO places. Firstly on the VPC
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Network ACL, and secondly on the security group network ACL attached to the
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EC2 instance. This has been tested as working for the official AMI image on
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the AWS Marketplace. (Locate the correct VPC and security group by navigating
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through the details pane below your EC2 instance in the AWS console).
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Spokes
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------
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The individual spoke configurations only differ in interface IP addresses.
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VyOS-Spoke-1 and VyOS-Spoke-2
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^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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.. code-block:: none
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set interfaces ethernet eth0 address '192.168.1.2/30'
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set interfaces tunnel tun100 address '10.0.0.1/32'
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set interfaces tunnel tun100 enable-multicast
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set interfaces tunnel tun100 encapsulation 'gre'
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set interfaces tunnel tun100 parameters ip key '42'
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set interfaces tunnel tun100 source-interface 'eth0'
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set protocols nhrp tunnel tun100 authentication 'test123'
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set protocols nhrp tunnel tun100 holdtime '300'
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set protocols nhrp tunnel tun100 multicast 'dynamic'
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set protocols nhrp tunnel tun100 network-id '1'
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set protocols nhrp tunnel tun100 nhs tunnel-ip dynamic nbma '192.168.0.2'
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set protocols nhrp tunnel tun100 registration-no-unique
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set protocols nhrp tunnel tun100 shortcut
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set protocols static route 0.0.0.0/0 next-hop 192.168.1.1
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set protocols static route 10.0.0.0/24 next-hop 10.0.0.100
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set vpn ipsec esp-group ESP-HUB lifetime '1800'
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set vpn ipsec esp-group ESP-HUB mode 'transport'
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set vpn ipsec esp-group ESP-HUB pfs 'dh-group2'
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set vpn ipsec esp-group ESP-HUB proposal 1 encryption 'aes256'
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set vpn ipsec esp-group ESP-HUB proposal 1 hash 'sha1'
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set vpn ipsec ike-group IKE-HUB key-exchange 'ikev1'
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set vpn ipsec ike-group IKE-HUB lifetime '3600'
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set vpn ipsec ike-group IKE-HUB proposal 1 dh-group '2'
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set vpn ipsec ike-group IKE-HUB proposal 1 encryption 'aes256'
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set vpn ipsec ike-group IKE-HUB proposal 1 hash 'sha1'
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set vpn ipsec interface 'eth0'
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set vpn ipsec profile NHRPVPN authentication mode 'pre-shared-secret'
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set vpn ipsec profile NHRPVPN authentication pre-shared-secret 'secret'
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set vpn ipsec profile NHRPVPN bind tunnel 'tun100'
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set vpn ipsec profile NHRPVPN esp-group 'ESP-HUB'
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set vpn ipsec profile NHRPVPN ike-group 'IKE-HUB'
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Cisco-Spoke-3
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^^^^^^^^^^^^^
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.. code-block:: none
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crypto isakmp policy 10
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encr aes 256
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authentication pre-share
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group 2
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lifetime 3600
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crypto isakmp key secret address 0.0.0.0
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!
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!
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crypto ipsec transform-set DMVPNESP esp-aes 256 esp-sha-hmac
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mode transport
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!
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crypto ipsec profile DMVPNPROFILE
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set security-association lifetime seconds 1800
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set transform-set DMVPNESP
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set pfs group2
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!
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!
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!
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!
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!
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!
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!
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interface Tunnel100
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ip address 10.0.0.3 255.255.255.0
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no ip redirects
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ip nhrp authentication test123
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ip nhrp map multicast dynamic
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ip nhrp network-id 1
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ip nhrp holdtime 300
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ip nhrp nhs 10.0.0.100 nbma 192.168.0.2
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ip nhrp registration no-unique
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ip nhrp redirect
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tunnel source GigabitEthernet0/0
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tunnel mode gre multipoint
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tunnel key 42
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tunnel protection ipsec profile DMVPNPROFILE
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!
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interface GigabitEthernet0/0
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ip address 192.168.3.2 255.255.255.252
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duplex auto
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speed auto
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media-type rj45
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!
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ip route 0.0.0.0 0.0.0.0 192.168.3.1
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Monitoring DMVPN Network
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^^^^^^^^^^^^^^^^^^^^^^^^
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Let send ICMP packets from VyOS-SPOKE-1 to Cisco-SPOKE-3
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.. code-block:: none
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vyos@vyos:~$ ping 10.0.0.3
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PING 10.0.0.3 (10.0.0.3) 56(84) bytes of data.
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64 bytes from 10.0.0.3: icmp_seq=1 ttl=255 time=3.44 ms
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64 bytes from 10.0.0.3: icmp_seq=2 ttl=255 time=3.07 ms
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^C
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--- 10.0.0.3 ping statistics ---
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2 packets transmitted, 2 received, 0% packet loss, time 1002ms
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rtt min/avg/max/mdev = 3.072/3.257/3.442/0.185 ms
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Monitoring on HUB
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^^^^^^^^^^^^^^^^^
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.. code-block:: none
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vyos@vyos:~$ show ip nhrp cache
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Iface Type Protocol NBMA Claimed NBMA Flags Identity
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tun100 dynamic 10.0.0.1 192.168.1.2 192.168.1.2 T 192.168.1.2
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tun100 dynamic 10.0.0.3 192.168.3.2 192.168.3.2 T 192.168.3.2
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tun100 dynamic 10.0.0.2 192.168.2.2 192.168.2.2 T 192.168.2.2
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tun100 local 10.0.0.100 192.168.0.2 192.168.0.2 -
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vyos@vyos:~$ show vpn ipsec sa
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Connection State Uptime Bytes In/Out Packets In/Out Remote address Remote ID Proposal
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-------------------------- ------- -------- -------------- ---------------- ---------------- ----------- ----------------------------------
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dmvpn-NHRPVPN-tun100-child up 3m46s 230B/270B 2/2 192.168.1.2 192.168.1.2 AES_CBC_256/HMAC_SHA1_96/MODP_1024
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dmvpn-NHRPVPN-tun100-child up 5m48s 460B/540B 4/4 192.168.2.2 192.168.2.2 AES_CBC_256/HMAC_SHA1_96/MODP_1024
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dmvpn-NHRPVPN-tun100-child up 16m26s 1K/1K 13/12 192.168.3.2 192.168.3.2 AES_CBC_256/HMAC_SHA1_96/MODP_1024
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Monitoring on Spokes
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^^^^^^^^^^^^^^^^^^^^
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.. code-block:: none
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vyos@vyos:~$ show ip nhrp cache
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Iface Type Protocol NBMA Claimed NBMA Flags Identity
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tun100 local 10.0.0.1 192.168.1.2 192.168.1.2 -
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tun100 dynamic 10.0.0.3 192.168.3.2 192.168.3.2 T 192.168.3.2
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tun100 nhs 10.0.0.100 192.168.0.2 192.168.0.2 T 192.168.0.2
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vyos@vyos:~$ show ip nhrp nhs
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Iface FQDN NBMA Protocol
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tun100 192.168.0.2 192.168.0.2 10.0.0.100
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vyos@vyos:~$ show ip nhrp shortcut
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Type Prefix Via Identity
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dynamic 10.0.0.3/32 10.0.0.3 192.168.3.2
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vyos@vyos:~$ show vpn ipsec sa
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Connection State Uptime Bytes In/Out Packets In/Out Remote address Remote ID Proposal
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-------------------------- ------- -------- -------------- ---------------- ---------------- ----------- ----------------------------------
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dmvpn-NHRPVPN-tun100-child up 6m43s 898B/695B 7/6 192.168.0.2 192.168.0.2 AES_CBC_256/HMAC_SHA1_96/MODP_1024
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dmvpn-NHRPVPN-tun100-child up 49s 215B/187B 2/2 192.168.3.2 192.168.3.2 AES_CBC_256/HMAC_SHA1_96/MODP_1024
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